A. Rita Gonçalves, I. Luci Conceição, Rui P. Carvalho, Sofia R. Costa
Kiwifruit, Actinidia spp., is an important crop worldwide and its cultivation has been increasing in Portugal. Kiwifruit plants are susceptible to plant‐parasitic nematodes (PPNs), including Meloidogyne spp. M. hapla and M. incognita have been reported to affect kiwifruit in major production regions worldwide, although information is lacking on the distribution and identity of PPNs associated with kiwifruit orchards in Portugal. Moreover, research is scarce on the drivers of PPN communities in this crop. Our primary objective was to investigate the diversity, density and distribution of PPNs within kiwifruit orchards of Portugal and to elucidate the influence of environmental factors on their community composition. Additionally, we aimed to evaluate population densities and identity of Meloidogyne spp. Nematodes were extracted from composite soil and root samples collected from orchards. Analysis of soil nematode communities suggested bacterial‐driven decomposition and high nutrient enrichment in these soils. Sixteen different genera of PPNs were detected, with Meloidogyne spp. as the dominant genus, mostly represented by a single species, M. hapla. PPN communities exhibited low richness, and β‐diversity analysis indicated a high degree of similarity among them. Additionally, their composition was significantly influenced by soil and climatic parameters. We found that 37 out of 40 kiwifruit orchards in Portugal were infested by root‐knot nematodes. The unexpectedly low species diversity, dominated by M. hapla, merits further research to establish underlying factors for its high incidence in this crop and to assess the impact of these nematodes on kiwifruit performance and productivity.
{"title":"Meloidogyne hapla dominates plant‐parasitic nematode communities associated with kiwifruit orchards in Portugal","authors":"A. Rita Gonçalves, I. Luci Conceição, Rui P. Carvalho, Sofia R. Costa","doi":"10.1111/ppa.14005","DOIUrl":"https://doi.org/10.1111/ppa.14005","url":null,"abstract":"Kiwifruit, <jats:italic>Actinidia</jats:italic> spp., is an important crop worldwide and its cultivation has been increasing in Portugal. Kiwifruit plants are susceptible to plant‐parasitic nematodes (PPNs), including <jats:italic>Meloidogyne</jats:italic> spp. <jats:italic>M. hapla</jats:italic> and <jats:italic>M</jats:italic>. <jats:italic>incognita</jats:italic> have been reported to affect kiwifruit in major production regions worldwide, although information is lacking on the distribution and identity of PPNs associated with kiwifruit orchards in Portugal. Moreover, research is scarce on the drivers of PPN communities in this crop. Our primary objective was to investigate the diversity, density and distribution of PPNs within kiwifruit orchards of Portugal and to elucidate the influence of environmental factors on their community composition. Additionally, we aimed to evaluate population densities and identity of <jats:italic>Meloidogyne</jats:italic> spp. Nematodes were extracted from composite soil and root samples collected from orchards. Analysis of soil nematode communities suggested bacterial‐driven decomposition and high nutrient enrichment in these soils. Sixteen different genera of PPNs were detected, with <jats:italic>Meloidogyne</jats:italic> spp. as the dominant genus, mostly represented by a single species, <jats:italic>M</jats:italic>. <jats:italic>hapla</jats:italic>. PPN communities exhibited low richness, and β‐diversity analysis indicated a high degree of similarity among them. Additionally, their composition was significantly influenced by soil and climatic parameters. We found that 37 out of 40 kiwifruit orchards in Portugal were infested by root‐knot nematodes. The unexpectedly low species diversity, dominated by <jats:italic>M</jats:italic>. <jats:italic>hapla</jats:italic>, merits further research to establish underlying factors for its high incidence in this crop and to assess the impact of these nematodes on kiwifruit performance and productivity.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"75 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142257781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haixu Liu, Zhuoqun Zhang, Ying Xu, Xiuming Du, Jingzhi Wen
The most devastating soilborne disease of soybean is Phytophthora root rot (PRR) caused by Phytophthora sojae. Biological control has emerged as an effective method of reducing soilborne diseases. The present study isolated the bacterial strain W82T‐44 from the rhizosphere soil of a resistant soybean variety Williams 82. This strain was identified as Bacillus amyloliquefaciens and exhibited a 92.4% inhibition of mycelial growth of P. sojae. W82T‐44 produced cellulase, siderophore and protease and significantly promoted soybean growth. W82T‐44 treatment, compared to the negative control, was found to significantly (p < 0.05) increase soybean plant height (22.34 vs. 18.47 cm), fresh weight of the whole plant (2.57 vs. 2.05 g), dry weight (0.43 vs. 0.32 g), total root length (266.80 vs. 182.53 cm), root area (27.10 vs. 17.84 cm2) and root volume (1.88 vs. 1.16 cm3). The fermentation filtrate of W82T‐44 had significant inhibitory effects on mycelial growth, oospore formation and cyst germination in P. sojae and additionally promoted zoospore encystment. W82T‐44 possessed genes involved in lipopeptide synthesis, including bacilysin, surfactin, fengycin and bacillomycin. Moreover, it significantly upregulated pathogenesis‐related genes (β‐1,3‐glucanase, nonexpressor of pathogenesis‐related gene 1, chitinase) and genes encoding defence enzymes (polyphenol oxidase, phenylalanine ammonia‐lyase, peroxidase) in soybean roots (p < 0.05). The PRR disease index of soybean treated with the W82T‐44 strain was significantly lower (11.67) than the negative control (40.00; p < 0.05). The present study indicates the potential of B. amyloliquefaciens W82T‐44 as a biological control agent against PRR from various perspectives.
{"title":"The growth‐promoting effects of Bacillus amyloliquefaciens W82T‐44 on soybean and its biocontrol potential against soybean Phytophthora root rot","authors":"Haixu Liu, Zhuoqun Zhang, Ying Xu, Xiuming Du, Jingzhi Wen","doi":"10.1111/ppa.13994","DOIUrl":"https://doi.org/10.1111/ppa.13994","url":null,"abstract":"The most devastating soilborne disease of soybean is Phytophthora root rot (PRR) caused by <jats:italic>Phytophthora sojae</jats:italic>. Biological control has emerged as an effective method of reducing soilborne diseases. The present study isolated the bacterial strain W82T‐44 from the rhizosphere soil of a resistant soybean variety Williams 82. This strain was identified as <jats:italic>Bacillus amyloliquefaciens</jats:italic> and exhibited a 92.4% inhibition of mycelial growth of <jats:italic>P</jats:italic>. <jats:italic>sojae</jats:italic>. W82T‐44 produced cellulase, siderophore and protease and significantly promoted soybean growth. W82T‐44 treatment, compared to the negative control, was found to significantly (<jats:italic>p</jats:italic> < 0.05) increase soybean plant height (22.34 vs. 18.47 cm), fresh weight of the whole plant (2.57 vs. 2.05 g), dry weight (0.43 vs. 0.32 g), total root length (266.80 vs. 182.53 cm), root area (27.10 vs. 17.84 cm<jats:sup>2</jats:sup>) and root volume (1.88 vs. 1.16 cm<jats:sup>3</jats:sup>). The fermentation filtrate of W82T‐44 had significant inhibitory effects on mycelial growth, oospore formation and cyst germination in <jats:italic>P</jats:italic>. <jats:italic>sojae</jats:italic> and additionally promoted zoospore encystment. W82T‐44 possessed genes involved in lipopeptide synthesis, including bacilysin, surfactin, fengycin and bacillomycin. Moreover, it significantly upregulated pathogenesis‐related genes (β‐1,3‐glucanase, nonexpressor of pathogenesis‐related gene 1, chitinase) and genes encoding defence enzymes (polyphenol oxidase, phenylalanine ammonia‐lyase, peroxidase) in soybean roots (<jats:italic>p</jats:italic> < 0.05). The PRR disease index of soybean treated with the W82T‐44 strain was significantly lower (11.67) than the negative control (40.00; <jats:italic>p</jats:italic> < 0.05). The present study indicates the potential of <jats:italic>B</jats:italic>. <jats:italic>amyloliquefaciens</jats:italic> W82T‐44 as a biological control agent against PRR from various perspectives.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"66 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Florence Yaméogo, Kevin Ben Fabrice Zerbo, Laurence Blondin, Léonard Ouedraogo, Irenée Somda, Valerie Verdier, Boris Szurek, Issa Wonni
Cassava bacterial blight (CBB), caused by Xanthomonas phaseoli pv. manihotis (Xpm), poses a significant threat to cassava production in Burkina Faso. Prior to this study, the geographical distribution, incidence and origin of CBB introductions were poorly understood. In this investigation, we assessed the incidence of CBB in major cassava‐cropping regions and analysed the genetic diversity of 344 Xpm strains collected from 19 fields between 2015 and 2016, using a multilocus variable number of tandem repeat analysis (MLVA) scheme targeting 14 microsatellite markers. Our results reveal the presence of CBB in three out of four cropping regions, with incidences ranging from 0% to 100% at locality and variety scale. Burkina Faso's Xpm strains exhibited high genetic diversity at multiple levels, including country scale (He = 0.6), cropping region (0.43 to 0.57), locality (0.25 to 0.50) and field (0.25 to 0.52). Pairwise comparisons among populations from different cropping areas indicated a strong genetic differentiation. The categorical minimum spanning tree reveals that the Cascades region has the higher diversity indices and consequently could be the origin site of dispersion of Xpm in the other cropping regions of cassava. Human activities play a major role in the dissemination of Xpm through cassava cuttings. The importance of the sanitary state of cuttings must be emphasized in order to avoid CBB and ensure good cassava production.
{"title":"Genetic diversity and incidence of cassava bacterial blight (CBB) caused by Xanthomonas phaseoli pv. manihotis in Burkina Faso","authors":"Florence Yaméogo, Kevin Ben Fabrice Zerbo, Laurence Blondin, Léonard Ouedraogo, Irenée Somda, Valerie Verdier, Boris Szurek, Issa Wonni","doi":"10.1111/ppa.13989","DOIUrl":"https://doi.org/10.1111/ppa.13989","url":null,"abstract":"Cassava bacterial blight (CBB), caused by <jats:italic>Xanthomonas phaseoli</jats:italic> pv. <jats:italic>manihotis</jats:italic> (Xpm), poses a significant threat to cassava production in Burkina Faso. Prior to this study, the geographical distribution, incidence and origin of CBB introductions were poorly understood. In this investigation, we assessed the incidence of CBB in major cassava‐cropping regions and analysed the genetic diversity of 344 Xpm strains collected from 19 fields between 2015 and 2016, using a multilocus variable number of tandem repeat analysis (MLVA) scheme targeting 14 microsatellite markers. Our results reveal the presence of CBB in three out of four cropping regions, with incidences ranging from 0% to 100% at locality and variety scale. Burkina Faso's Xpm strains exhibited high genetic diversity at multiple levels, including country scale (He = 0.6), cropping region (0.43 to 0.57), locality (0.25 to 0.50) and field (0.25 to 0.52). Pairwise comparisons among populations from different cropping areas indicated a strong genetic differentiation. The categorical minimum spanning tree reveals that the Cascades region has the higher diversity indices and consequently could be the origin site of dispersion of Xpm in the other cropping regions of cassava. Human activities play a major role in the dissemination of Xpm through cassava cuttings. The importance of the sanitary state of cuttings must be emphasized in order to avoid CBB and ensure good cassava production.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"21 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183745","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-09DOI: 10.1111/j.1365-3059.1995.tb00005.x
N. HEIBERG
The effects of raised beds, mulching, organic amendments and soil treatment with metalaxyl on raspberry root rot (Phytophthora fragariae var. rubi) were studied in a field experiment with two raspberry cultivars, Veten (highly susceptible) and Chilliwack, a less susceptible cultivar. Raised beds reduced the severity of root rot compared with flat beds. The best results for both cultivars were obtained with a combination of raised beds and metalaxyl treatment. As separate treatments, raised beds and metalaxyl had approximately the same effect. Mulching with grass or composted manure increased the severity of root rot.
通过对两个树莓栽培品种 Veten（高感病）和 Chilliwack（低感病栽培品种）进行田间试验，研究了高床、覆盖物、有机添加剂和土壤中施甲霜灵对树莓根腐病（Phytophthora fragariae var. rubi）的影响。与平床相比，高床降低了根腐病的严重程度。对这两种栽培品种来说，高床和甲霜灵处理相结合的效果最好。作为单独的处理方法，高床和甲霜灵的效果大致相同。用草或堆肥覆盖会增加根腐病的严重程度。
{"title":"Control of root rot of red raspberries caused by Phytophthora fragariae var. rubi","authors":"N. HEIBERG","doi":"10.1111/j.1365-3059.1995.tb00005.x","DOIUrl":"https://doi.org/10.1111/j.1365-3059.1995.tb00005.x","url":null,"abstract":"The effects of raised beds, mulching, organic amendments and soil treatment with metalaxyl on raspberry root rot (<jats:italic>Phytophthora fragariae</jats:italic> var. <jats:italic>rubi</jats:italic>) were studied in a field experiment with two raspberry cultivars, Veten (highly susceptible) and Chilliwack, a less susceptible cultivar. Raised beds reduced the severity of root rot compared with flat beds. The best results for both cultivars were obtained with a combination of raised beds and metalaxyl treatment. As separate treatments, raised beds and metalaxyl had approximately the same effect. Mulching with grass or composted manure increased the severity of root rot.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"34 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chen Chen, Harald Keunecke, Enzo Neu, Friedrich J. Kopisch‐Obuch, Bruce A. McDonald, Jessica Stapley
Cercospora leaf spot (CLS), caused by Cercospora beticola, is a major foliar disease impacting sugar beet production worldwide. The development of new resistant sugar beet hybrids is a powerful tool to better manage the disease, but it is unclear how these hybrids affect CLS epidemiology. We used a molecular epidemiology approach to study natural epidemics of CLS affecting two susceptible and two resistant sugar beet hybrids at two field sites. Infected plants were geotagged on a weekly basis. Isolations of C. beticola were made from infected leaves and genotyped using six simple‐sequence repeat loci to identify clones. We determined that CLS epidemics had a later onset in plots planted to resistant hybrids, but once the pathogen established an infection, there was little difference between resistant and susceptible hybrids in the probability of localized spread and dispersal. We found that different clones often infected the same leaf and that clusters of infected plants were often colonized by a mixture of clones. There was little overall difference in genetic diversity of C. beticola collected on resistant and susceptible hybrids; however, genotypic diversity was lower on the resistant hybrid at one site, suggestive of a selection bottleneck. At the end of the epidemic infections were not randomly distributed across the fields and we found that a single clone could spread over a distance of 100 m during a growing season.
由 Cercospora beticola 引起的 Cercospora 叶斑病（CLS）是影响全球甜菜生产的一种主要叶面病害。新的抗性甜菜杂交种的开发是更好地管理该病害的有力工具，但目前还不清楚这些杂交种如何影响 CLS 的流行。我们采用分子流行病学方法研究了在两个田间地点影响两种易感和两种抗性甜菜杂交种的 CLS 自然流行病。每周对受感染的植株进行地理标记。从受感染的叶片中分离出 C. beticola，并使用六个简单序列重复位点进行基因分型，以确定克隆。我们发现，在种植抗性杂交种的地块中，CLS流行病的发病时间较晚，但病原体一旦形成感染，抗性杂交种和易感杂交种在局部传播和扩散的概率上差别不大。我们发现，不同的克隆往往会感染同一片叶子，受感染的植株群往往由混合克隆定殖。在抗性杂交种和易感杂交种上收集到的 C. beticola 遗传多样性总体差异不大；但在一个地点，抗性杂交种的基因型多样性较低，这表明存在选择瓶颈。在疫情结束时，感染并不是随机分布在田间的，我们发现在一个生长季节中，一个克隆的传播距离可达 100 米。
{"title":"Molecular epidemiology of Cercospora leaf spot on resistant and susceptible sugar beet hybrids","authors":"Chen Chen, Harald Keunecke, Enzo Neu, Friedrich J. Kopisch‐Obuch, Bruce A. McDonald, Jessica Stapley","doi":"10.1111/ppa.13998","DOIUrl":"https://doi.org/10.1111/ppa.13998","url":null,"abstract":"Cercospora leaf spot (CLS), caused by <jats:italic>Cercospora beticola</jats:italic>, is a major foliar disease impacting sugar beet production worldwide. The development of new resistant sugar beet hybrids is a powerful tool to better manage the disease, but it is unclear how these hybrids affect CLS epidemiology. We used a molecular epidemiology approach to study natural epidemics of CLS affecting two susceptible and two resistant sugar beet hybrids at two field sites. Infected plants were geotagged on a weekly basis. Isolations of <jats:italic>C</jats:italic>. <jats:italic>beticola</jats:italic> were made from infected leaves and genotyped using six simple‐sequence repeat loci to identify clones. We determined that CLS epidemics had a later onset in plots planted to resistant hybrids, but once the pathogen established an infection, there was little difference between resistant and susceptible hybrids in the probability of localized spread and dispersal. We found that different clones often infected the same leaf and that clusters of infected plants were often colonized by a mixture of clones. There was little overall difference in genetic diversity of <jats:italic>C</jats:italic>. <jats:italic>beticola</jats:italic> collected on resistant and susceptible hybrids; however, genotypic diversity was lower on the resistant hybrid at one site, suggestive of a selection bottleneck. At the end of the epidemic infections were not randomly distributed across the fields and we found that a single clone could spread over a distance of 100 m during a growing season.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"10 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aïda Magdalena Fullana, Alejandro Expósito, Montserrat Pujolà, Isabel Achaerandio, Marina Cunquero, Pablo Loza‐Alvarez, Ariadna Giné, Francisco Javier Sorribas
Meloidogyne spp. are the most devastating plant‐parasitic nematodes affecting tomato worldwide. Although resistant cultivars and rootstocks are used, selection for virulence occurs in the pathogen. Consequently, using other resistance sources, such as Solanum torvum, could improve resistance durability. Several experiments in microplots and plastic greenhouses were carried out to determine the potential use of S. torvum as a tomato rootstock to protect against M. incognita and M. javanica. In microplots, the relationship between nematode density at transplanting (Pi) and multiplication rate did not differ between Meloidogyne species in either ungrafted or grafted tomato. However, maximum multiplication rate and maximum density on grafted tomato were 1.27% and 2.93% those on ungrafted, respectively. The grafted tomato plants yielded between 2.9 and 7.5 more times than the ungrafted plants at Pi ≥ 100 eggs + J2s per 100 cm3 of soil, but no differences were observed in plastic greenhouse where a large amount of scion‐rooting occurred. In microplots, the quality of the tomato fruits of ungrafted and grafted plants was affected by the Pi. In parallel, some pot experiments were conducted on S. torvum and susceptible eggplant to determine the putative selection for nematode virulence to S. torvum and the nematode fitness cost. These showed that the nematode subpopulations infected and reproduced less on S. torvum than on eggplant. However, the female fertility was only reduced after development of three or four subpopulations on S. torvum. Finally, a histopathological study showed that nematode infection and development in S. torvum was delayed compared to eggplant.
Meloidogyne spp.是影响全球番茄的最具破坏性的植物寄生线虫。虽然使用了抗性栽培品种和砧木，但病原体也会对毒性进行选择。因此，使用其他抗性来源（如 Solanum torvum）可以提高抗性的持久性。我们在微小地块和塑料大棚中进行了几项实验，以确定是否有可能使用 S. torvum 作为番茄砧木来抵御 M. incognita 和 M. javanica。在微小地块中，移栽时线虫密度（Pi）与繁殖率之间的关系在未嫁接或嫁接番茄中的 Meloidogyne 种类之间没有差异。但是，嫁接番茄的最大繁殖率和最大密度分别是未嫁接番茄的 1.27% 和 2.93%。当每 100 立方厘米土壤中的 Pi ≥ 100 个卵 + J2s 时，嫁接番茄植株的产量是未嫁接植株的 2.9 至 7.5 倍，但在塑料大棚中没有观察到差异，因为在塑料大棚中发生了大量接穗生根现象。在小地块中，未嫁接和嫁接植株的番茄果实质量受 Pi 的影响。与此同时，还对 S. torvum 和易感茄子进行了一些盆栽实验，以确定线虫对 S. torvum 的毒力选择以及线虫的适应成本。结果表明，线虫亚群对 S. torvum 的感染和繁殖能力低于对茄子的感染和繁殖能力。然而，只有在 S. torvum 上发展出三到四个亚群后，雌虫的繁殖力才会降低。最后，组织病理学研究表明，线虫在 S. torvum 上的感染和发育比在茄子上要晚。
{"title":"Effect of grafting tomato onto Solanum torvum on the population dynamics of Meloidogyne incognita and M. javanica and crop yield losses","authors":"Aïda Magdalena Fullana, Alejandro Expósito, Montserrat Pujolà, Isabel Achaerandio, Marina Cunquero, Pablo Loza‐Alvarez, Ariadna Giné, Francisco Javier Sorribas","doi":"10.1111/ppa.13991","DOIUrl":"https://doi.org/10.1111/ppa.13991","url":null,"abstract":"<jats:italic>Meloidogyne</jats:italic> spp. are the most devastating plant‐parasitic nematodes affecting tomato worldwide. Although resistant cultivars and rootstocks are used, selection for virulence occurs in the pathogen. Consequently, using other resistance sources, such as <jats:italic>Solanum torvum</jats:italic>, could improve resistance durability. Several experiments in microplots and plastic greenhouses were carried out to determine the potential use of <jats:italic>S</jats:italic>. <jats:italic>torvum</jats:italic> as a tomato rootstock to protect against <jats:italic>M</jats:italic>. <jats:italic>incognita</jats:italic> and <jats:italic>M</jats:italic>. <jats:italic>javanica</jats:italic>. In microplots, the relationship between nematode density at transplanting (<jats:italic>Pi</jats:italic>) and multiplication rate did not differ between <jats:italic>Meloidogyne</jats:italic> species in either ungrafted or grafted tomato. However, maximum multiplication rate and maximum density on grafted tomato were 1.27% and 2.93% those on ungrafted, respectively. The grafted tomato plants yielded between 2.9 and 7.5 more times than the ungrafted plants at <jats:italic>Pi</jats:italic> ≥ 100 eggs + J2s per 100 cm<jats:sup>3</jats:sup> of soil, but no differences were observed in plastic greenhouse where a large amount of scion‐rooting occurred. In microplots, the quality of the tomato fruits of ungrafted and grafted plants was affected by the <jats:italic>Pi</jats:italic>. In parallel, some pot experiments were conducted on <jats:italic>S</jats:italic>. <jats:italic>torvum</jats:italic> and susceptible eggplant to determine the putative selection for nematode virulence to <jats:italic>S</jats:italic>. <jats:italic>torvum</jats:italic> and the nematode fitness cost. These showed that the nematode subpopulations infected and reproduced less on <jats:italic>S</jats:italic>. <jats:italic>torvum</jats:italic> than on eggplant. However, the female fertility was only reduced after development of three or four subpopulations on <jats:italic>S</jats:italic>. <jats:italic>torvum</jats:italic>. Finally, a histopathological study showed that nematode infection and development in <jats:italic>S</jats:italic>. <jats:italic>torvum</jats:italic> was delayed compared to eggplant.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"4 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pseudoperonospora cubensis, causal agent of cucurbit downy mildew, is a common and highly variable pathogen of cucurbit vegetables. Pathogen virulence can be considered on two different levels, that is, pathotypes and races. Pathotypes characterize the interactions between pathogen isolates and the set of genotypes represented by different species and/or genera of the host plant family. Races are characterized by the interactions between pathogen isolates and the set of genotypes (e.g., cultivars, lines, accessions) of one host species (or very closely related species). Differential sets for pathotype and/or race determination are composed of distinct (different) genotypes. Until recently, only differentiation of pathotypes was used to characterize P. cubensis. Most recent research of virulence variation in P. cubensis populations in the Czech Republic working with the Cucumis melo differential set demonstrated the existence of a large number of races of this pathogen. The differential capacity of this set was primarily created for the determination and denomination of virulence phenotypes/races of cucurbit powdery mildew (Golovinomyces orontii, Podosphaera xanthii). However, this set is also efficient for differentiating virulence phenotypes in P. cubensis. This means that one set of C. melo differential genotypes can be used for two independent plant–pathogen systems: cucurbit powdery mildew and cucurbit downy mildew. Results showed that isolates of P. cubensis developing identical virulence reaction patterns at the level of pathotype, develop different reaction patterns at the level of races and vice versa. It is demonstrated and explained that pathotypes and races are two different categories for the assessment of virulence variation, which should be clearly defined, recognized and used within international scientific and breeding communities.
Pseudoperonospora cubensis 是葫芦霜霉病的病原菌，是葫芦科蔬菜的一种常见病原菌，而且变异很大。病原体的毒力可以从两个不同的层面来考虑，即病原型和种族。病原体分离物与寄主植物科不同种和/或属所代表的基因型之间的相互作用是病原体的特征。种族的特征是病原体分离物与一个宿主物种（或关系非常密切的物种）的基因型集（如栽培品种、品系、入选品种）之间的相互作用。用于确定病原型和/或种族的差异集由不同（差异）的基因型组成。直到最近，只有病原型的差异才被用来描述 P. cubensis 的特征。最近在捷克共和国利用瓜类差异集对 P. cubensis 种群的毒力变异进行的研究表明，这种病原体存在大量的种族。该差异集主要用于确定和划分葫芦白粉病（Golovinomyces orontii, Podosphaera xanthii）的毒力表型/品系。不过，这套方法也能有效区分 P. cubensis 的毒力表型。这意味着一套瓜类差异基因型可用于两个独立的植物病原系统：葫芦白粉病和葫芦霜霉病。结果表明，在病原型层面上具有相同毒力反应模式的立枯丝核菌分离株，在品系层面上具有不同的反应模式，反之亦然。结果表明并解释了病原型和品系是评估毒力变异的两个不同类别，国际科学界和育种界应明确定义、认可和使用这两个类别。
{"title":"Pathotypes and races of Pseudoperonospora cubensis: Two concepts of virulence differentiation","authors":"Aleš Lebeda, Eva Křístková, Božena Sedláková","doi":"10.1111/ppa.13993","DOIUrl":"https://doi.org/10.1111/ppa.13993","url":null,"abstract":"<jats:italic>Pseudoperonospora cubensis</jats:italic>, causal agent of cucurbit downy mildew, is a common and highly variable pathogen of cucurbit vegetables. Pathogen virulence can be considered on two different levels, that is, pathotypes and races. Pathotypes characterize the interactions between pathogen isolates and the set of genotypes represented by different species and/or genera of the host plant family. Races are characterized by the interactions between pathogen isolates and the set of genotypes (e.g., cultivars, lines, accessions) of one host species (or very closely related species). Differential sets for pathotype and/or race determination are composed of distinct (different) genotypes. Until recently, only differentiation of pathotypes was used to characterize <jats:italic>P</jats:italic>. <jats:italic>cubensis</jats:italic>. Most recent research of virulence variation in <jats:italic>P</jats:italic>. <jats:italic>cubensis</jats:italic> populations in the Czech Republic working with the <jats:italic>Cucumis melo</jats:italic> differential set demonstrated the existence of a large number of races of this pathogen. The differential capacity of this set was primarily created for the determination and denomination of virulence phenotypes/races of cucurbit powdery mildew (<jats:italic>Golovinomyces orontii</jats:italic>, <jats:italic>Podosphaera xanthii</jats:italic>). However, this set is also efficient for differentiating virulence phenotypes in <jats:italic>P</jats:italic>. <jats:italic>cubensis</jats:italic>. This means that one set of <jats:italic>C</jats:italic>. <jats:italic>melo</jats:italic> differential genotypes can be used for two independent plant–pathogen systems: cucurbit powdery mildew and cucurbit downy mildew. Results showed that isolates of <jats:italic>P</jats:italic>. <jats:italic>cubensis</jats:italic> developing identical virulence reaction patterns at the level of pathotype, develop different reaction patterns at the level of races and vice versa. It is demonstrated and explained that pathotypes and races are two different categories for the assessment of virulence variation, which should be clearly defined, recognized and used within international scientific and breeding communities.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"174 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xylella fastidiosa is a destructive bacterial plant pathogen affecting hundreds of plant families, including important crops such as olive and citrus trees and vines. The pathogenicity of this bacterium rests in a group of genes that encode toxins, enzymes, fimbrial/afimbrial adhesins, cell–cell aggregation proteins and other virulence factors. We investigated the contribution of mobile genetic elements (MGEs) to the pathogenicity of X. fastidiosa. Using computational tools, we analysed 94 X. fastidiosa genomes corresponding to the three most important subspecies to identify insertion sequences (ISs) and prophages. Results indicate that the distribution and diversity of ISs are modest, with a few families widespread throughout the subspecies of X. fastidiosa. The prophages are abundant, and play a more significant role in the pathogenicity of X. fastidiosa. Prophages are common in the subspecies of X. fastidiosa and contribute to numerous genes related to pathogenicity. The phylogenetic analyses suggest that prophages are recently acquired and that the rearranging of pathogenicity genes triggered by them could generate strains with new pathogenic capacities. Finally, the contribution of MGEs to the pathogenesis of X. fastidiosa was evidenced by determining their association with virulence genes using a Bayesian framework for phylogenetic analysis of character evolution.
{"title":"Mobile genetic elements of Xylella fastidiosa and their contribution to pathogenicity","authors":"Dennis Jimenez, Diego Beltran, José A. Castillo","doi":"10.1111/ppa.13992","DOIUrl":"https://doi.org/10.1111/ppa.13992","url":null,"abstract":"<jats:italic>Xylella fastidiosa</jats:italic> is a destructive bacterial plant pathogen affecting hundreds of plant families, including important crops such as olive and citrus trees and vines. The pathogenicity of this bacterium rests in a group of genes that encode toxins, enzymes, fimbrial/afimbrial adhesins, cell–cell aggregation proteins and other virulence factors. We investigated the contribution of mobile genetic elements (MGEs) to the pathogenicity of <jats:italic>X. fastidiosa</jats:italic>. Using computational tools, we analysed 94 <jats:italic>X. fastidiosa</jats:italic> genomes corresponding to the three most important subspecies to identify insertion sequences (ISs) and prophages. Results indicate that the distribution and diversity of ISs are modest, with a few families widespread throughout the subspecies of <jats:italic>X. fastidiosa</jats:italic>. The prophages are abundant, and play a more significant role in the pathogenicity of <jats:italic>X. fastidiosa</jats:italic>. Prophages are common in the subspecies of <jats:italic>X. fastidiosa</jats:italic> and contribute to numerous genes related to pathogenicity. The phylogenetic analyses suggest that prophages are recently acquired and that the rearranging of pathogenicity genes triggered by them could generate strains with new pathogenic capacities. Finally, the contribution of MGEs to the pathogenesis of <jats:italic>X. fastidiosa</jats:italic> was evidenced by determining their association with virulence genes using a Bayesian framework for phylogenetic analysis of character evolution.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"23 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Olaide Mary Ogunsanya, Moruf Ayodele Adebisi, Akinola Rasheed Popoola, Clement Gboyega Afolabi, Olaniyi Oyatomi, Richard Colgan, Andrew Armitage, Elinor Thompson, Michael Abberton, Alejandro Ortega‐Beltran
African yam bean (AYB; Sphenostylis stenocarpa) is an underutilized legume indigenous to Africa with great potential to enhance food security and offer nutritional and medicinal opportunities. However, low grain yield caused by fungal diseases, including pod blight and leaf tip dieback, deters farmers from large‐scale cultivation. To determine the prevalence of fungal diseases affecting leaves, pods and flowers of AYB, a survey was conducted in 2018 and 2019 in major AYB‐growing areas in Nigeria. Leaf tip dieback, flower bud rot and pod blight were the most common symptoms. Morphological and molecular assays were conducted to identify the causal agents of the observed diseases. In all the samples examined, fungi from eight genera were isolated from diseased leaves, buds and pods. Koch's postulates were fulfilled only for fungi belonging to the Colletotrichum genus. Fungi from the other seven genera did not produce disease symptoms in healthy AYB tissues. Several Colletotrichum isolates were characterized by sequencing the rDNA internal transcribed spacer (ITS), glyceraldehyde‐3‐phosphate dehydrogenase, calmodulin and ApMAT loci. A combined phylogenetic analysis revealed four Colletotrichum species: C. siamense, C. theobromicola and C. fructicola, which were recovered from diseased leaves, and C. truncatum, recovered from diseased pods and buds. Our results are useful to gear efforts to develop integrated management strategies to control diseases affecting AYB in Nigeria and elsewhere. Availability of such strategies may stimulate greater AYB cultivation, which can contribute to diet diversification, something repeatedly advocated by a range of stakeholders to increase food security and prosperity of smallholder farmers.
{"title":"Morphological, pathological and phylogenetic analyses identify a diverse group of Colletotrichum spp. causing leaf, pod and flower diseases on the orphan legume African yam bean","authors":"Olaide Mary Ogunsanya, Moruf Ayodele Adebisi, Akinola Rasheed Popoola, Clement Gboyega Afolabi, Olaniyi Oyatomi, Richard Colgan, Andrew Armitage, Elinor Thompson, Michael Abberton, Alejandro Ortega‐Beltran","doi":"10.1111/ppa.13995","DOIUrl":"https://doi.org/10.1111/ppa.13995","url":null,"abstract":"African yam bean (AYB; <jats:italic>Sphenostylis stenocarpa</jats:italic>) is an underutilized legume indigenous to Africa with great potential to enhance food security and offer nutritional and medicinal opportunities. However, low grain yield caused by fungal diseases, including pod blight and leaf tip dieback, deters farmers from large‐scale cultivation. To determine the prevalence of fungal diseases affecting leaves, pods and flowers of AYB, a survey was conducted in 2018 and 2019 in major AYB‐growing areas in Nigeria. Leaf tip dieback, flower bud rot and pod blight were the most common symptoms. Morphological and molecular assays were conducted to identify the causal agents of the observed diseases. In all the samples examined, fungi from eight genera were isolated from diseased leaves, buds and pods. Koch's postulates were fulfilled only for fungi belonging to the <jats:italic>Colletotrichum</jats:italic> genus. Fungi from the other seven genera did not produce disease symptoms in healthy AYB tissues. Several <jats:italic>Colletotrichum</jats:italic> isolates were characterized by sequencing the rDNA internal transcribed spacer (ITS), <jats:italic>glyceraldehyde‐3‐phosphate dehydrogenase</jats:italic>, <jats:italic>calmodulin</jats:italic> and <jats:italic>ApMAT</jats:italic> loci. A combined phylogenetic analysis revealed four <jats:italic>Colletotrichum</jats:italic> species: <jats:italic>C</jats:italic>. <jats:italic>siamense</jats:italic>, <jats:italic>C</jats:italic>. <jats:italic>theobromicola</jats:italic> and <jats:italic>C</jats:italic>. <jats:italic>fructicola</jats:italic>, which were recovered from diseased leaves, and <jats:italic>C</jats:italic>. <jats:italic>truncatum</jats:italic>, recovered from diseased pods and buds. Our results are useful to gear efforts to develop integrated management strategies to control diseases affecting AYB in Nigeria and elsewhere. Availability of such strategies may stimulate greater AYB cultivation, which can contribute to diet diversification, something repeatedly advocated by a range of stakeholders to increase food security and prosperity of smallholder farmers.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"30 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Monitoring of Phyllosticta citricarpa (causal agent of citrus black spot [CBS]) inoculum in orchards has previously been performed using volumetric spore traps. However, volumetric traps are nonspecific, and only capture ascospores (not pycnidiospores) of different Phyllosticta species. This research aimed to monitor and quantify the DNA of P. citricarpa using young citrus plants as a spore trap combined with quantitative PCR (qPCR), as well as quantify the number of ascospores and pycnidiospores, and to correlate results with weather variables. Citrus nursery plants were placed as traps under and outside tree canopies during fruit developmental stages (from October to July) in two seasons in commercial ‘Valencia’ sweet orange orchards. DNA was extracted from trap leaves to quantify P. citricarpa inoculum by qPCR of the ribosomal internal transcribed spacer 1 (ITS1 rRNA) region of P. citricarpa (Pc‐ITS). Correlations of Pc‐ITS to rainy days, leaf wetness and temperature were performed. Overall, the highest numbers of 400 Pc‐ITS/cm2 of leaf tissue, which represented up to 12 ascospores or pycnidiospores per cm2, were detected on leaves sampled from October to March, regardless of the trap position, season and orchard. Trap plants placed under canopies had up to 20‐fold more Pc‐ITS than those placed outside. Rainy days and leaf wetness were the variables most positively correlated with Pc‐ITS. Both results in the fluctuation of P. citricarpa inoculum in orchards and the most favourable weather variables associated with inoculum production contribute to better understanding of the critical periods for CBS management in citrus‐growing areas.
{"title":"Monitoring quantities of Phyllosticta citricarpa inoculum in sweet orange orchards using qPCR and young citrus plants as spore traps","authors":"Régis Oliveira Fialho, Rosana Goncalves Pereira, Leonardo Aparecido Brandão, Elaine Cristina Martins, Isabela Vescove Primiano, Paul Fourie, Providence Moyo, Lilian Amorim, Geraldo José Silva Junior","doi":"10.1111/ppa.13996","DOIUrl":"https://doi.org/10.1111/ppa.13996","url":null,"abstract":"Monitoring of <jats:italic>Phyllosticta citricarpa</jats:italic> (causal agent of citrus black spot [CBS]) inoculum in orchards has previously been performed using volumetric spore traps. However, volumetric traps are nonspecific, and only capture ascospores (not pycnidiospores) of different <jats:italic>Phyllosticta</jats:italic> species. This research aimed to monitor and quantify the DNA of <jats:italic>P</jats:italic>. <jats:italic>citricarpa</jats:italic> using young citrus plants as a spore trap combined with quantitative PCR (qPCR), as well as quantify the number of ascospores and pycnidiospores, and to correlate results with weather variables. Citrus nursery plants were placed as traps under and outside tree canopies during fruit developmental stages (from October to July) in two seasons in commercial ‘Valencia’ sweet orange orchards. DNA was extracted from trap leaves to quantify <jats:italic>P</jats:italic>. <jats:italic>citricarpa</jats:italic> inoculum by qPCR of the ribosomal internal transcribed spacer 1 (ITS1 rRNA) region of <jats:italic>P</jats:italic>. <jats:italic>citricarpa</jats:italic> (Pc‐ITS). Correlations of Pc‐ITS to rainy days, leaf wetness and temperature were performed. Overall, the highest numbers of 400 Pc‐ITS/cm<jats:sup>2</jats:sup> of leaf tissue, which represented up to 12 ascospores or pycnidiospores per cm<jats:sup>2</jats:sup>, were detected on leaves sampled from October to March, regardless of the trap position, season and orchard. Trap plants placed under canopies had up to 20‐fold more Pc‐ITS than those placed outside. Rainy days and leaf wetness were the variables most positively correlated with Pc‐ITS. Both results in the fluctuation of <jats:italic>P</jats:italic>. <jats:italic>citricarpa</jats:italic> inoculum in orchards and the most favourable weather variables associated with inoculum production contribute to better understanding of the critical periods for CBS management in citrus‐growing areas.","PeriodicalId":20075,"journal":{"name":"Plant Pathology","volume":"27 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142183751","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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