Journal of Plant Pathology最新文献

Coffee leaf rust (CLR), caused by Hemileia vastatrix Berk. and Br, stands as a globally significant disease responsible for diminishing the grain yield and quality of Coffea arabica L. As such, the need arises for a practical and dependable method to quantify CLR disease severity and propose effective management strategies. The creation of a diagrammatic scale, featuring color photographs, proves instrumental in enhancing severity assessment and disease estimation. Mutagenesis serves as a potent tool for improving crop traits, notably resistance to pests and diseases, by inducing genetic variability, thus fostering phenotypic diversity. The primary objective of this study was to craft a novel diagrammatic scale for leaf discs, designed to gauge the severity of coffee leaf rust in C. arabica L. cv. Catuaí plants treated with sodium azide (NaN3) and ethyl methane sulfonate (EMS). The assessment encompassed a thorough examination of incidence, severity, incubation period, and latency in plant leaf discs inoculated with CLR isolates, all carried out under rigorously controlled laboratory conditions. The scale’s construction hinged on the frequency distribution of severity and Weber-Fechner’s visual stimulus law, which facilitated the determination of minimum and maximum limits, as well as intermediary levels. The resulting scale comprises seven distinct levels spanning a range from 0 to 52.15% of the afflicted leaf area. Employing conglomerate analysis (Wilks, p < 0.0001) unveiled four groups of progenies exhibiting significantly different (p < 0.05) resistance responses to CLR. Notably, Plant E154 displayed an incidence rate of merely 0.3% for CLR, while the remaining plants, including A123, E6, E64, A127, CES5, A107, A93, E29, E116, and A101, showcased an incidence rate of less than 10%. In conclusion, this scale represents a suitable, valuable, and dependable tool for visually estimating CLR severity in coffee leaf discs.

Fusarium foot and root rot is one of the most important soilborne diseases of cereals, specifically on durum wheat which is the main cultivated species in the Mediterranean regions. This work aimed to evaluate the response of durum wheat and bread wheat to this disease under different climatic conditions. The disease parameters, grain yield loss as well as thousand kernel weight (TKW), heading date and height of plant were evaluated on 29 durum and bread wheat genotypes during two years. Overall, durum wheat grain yield was strongly and negatively correlated with disease parameters, heading date, and positively with plant height and TKW compared to bread wheat. In the drier year, the 24 durum wheat genotypes were more susceptible to the disease than the five bread wheat varieties while some of them showed less disease during the wetter year. Bread wheat maintained the same behavior in both years vs. durum wheat. Grain yield loss was higher on durum wheat compared to bread wheat. It was the same in both years (56 and 51%) for durum wheat and was significantly (p < 0.01) lower in the drier (24%) compared to the wetter year (44%) for bread wheat. This work confirmed the susceptibility of Tunisian durum wheat to the disease compared to bread wheat and calls attention to the potential vulnerability of this important Mediterranean food crop under a hotter, drier climate. More research is needed to investigate adaptation to drought and plant defense mechanisms and to breed for resistance to this disease.

Fire blight disease, caused by Erwinia amylovora is present worldwide and affects over 40 countries in Europe where it is listed as a quarantine or regulated pest often due to ineffective control strategies maladapted to the respective production systems. In Portugal, the disease was confirmed in 2010 and the occurrence of disease outbreaks in new production areas has risen over the years. The disease affects the national production of apple and pear fruits, with greater impact on the national pear variety ‘Rocha’, widely exported to European countries and Brazil. The mild temperatures and high relative humidity promote the progression of the disease during winter, revealing the potential activity of the bacterium in the latency period (LP) of the host. Infection alert risk using the established predictive models Maryblight TM, Cougarblight and BIS98 was put in place in 2013 by Centro Operativo e Tecnológico Hortofrutícola Nacional (COTHN). These attempts to control the spread of this disease, showed low accuracy for the Portuguese epidemiological reality. Within the framework of project Fire4CAST we developed a new epidemiological model to predict fire blight disease using a systems biology approach integrating microbiological, cytological and genomic pathogen data with phenological host development and climatic variables. The presence of E. amylovora was monitored in orchards with fire blight history using standard laboratory tests. Simultaneously, the implementation of immune-flow cytometry (IFCM) highlighted the viability of E. amylovora populations prevailing during winter and early spring, long before bloom risk period. The integration of the whole data set allowed the development of the Fire4CAST predictive model, able to monitor the expected infection date (EID) and to define accurate outbreak alarms. Fire4CAST model enabled the detection of outbreak risk during winter based on rules that consider climatic data variables, which were validated by effective presence of live and active E. amylovora populations and real-time quantitative PCR (qPCR) data, accomplishing a precision rate of 83%. Field application of Fire4CAST can hopefully guide the implementation of successful control strategies, leading to more sustainable pome chain production areas.

King grass (Pennisetum sinese), also known as sugar cane grass, is being affected by emerging leaf blast pathogen which is responsible for causing foliar disease in Baoshan City, Yunnan Province, China. The pathogen was isolated from the typical infected plants showing symptoms like eye-shaped and whitish color in the center with brown-black necrotic borders surrounded by a yellow halo sample on potato dextrose agar (PDA) media. The leaves of various plants including maize (Zea mays), hybrid rice (Oryza sativa), and wheat (Triticum aestivum), were inoculated with the pathogen in an in vitro assay to evaluate the infection potential of the pathogen and transmission risk. Our study verified that Psp1 is pathogenic to the king grass leaves and it is considered as the main causal agent of leaf blast in the study area. Further, morphological characterization and molecular analysis based on ITS region and LSU gene confirmed the pathogen as Pyricularia pennisetigena. During pathogenicity assay, both Psp1 and LP11 isolates of a rice blast pathogen induced symptoms of varying severity in a total of different nine plants. Among these, the pathogen Psp1 exhibited significant symptoms, including conidial emergence on king grass leaves (Pennisetum alopecuroides and Pe. flaccidum) indicating high pathogenicity to these plants. This suggests that Psp1 pose a considerable a high pathogenic risk to Pennisetum spp. This work lays a groundwork for future implementation of integrated management strategies for leaf blast in local king grass, offering a theoretical basis and research foundation for such endeavor.

Coffee berry disease (CBD) (caused by Colletotrichum kahawae Waller and Bridge), is the major limiting factor in coffee production and is markedly increasing, particularly in southern Ethiopia. Therefore, the current work was conducted with the objectives of (1) assessing the current status of the disease and (2) identifying major biophysical factors associated with disease intensity. Field surveys were conducted to perform disease assessments and identify major biophysical factors associated with CBD intensity across six districts from mid-July to August 2021 cropping season. The mean CBD incidence and severity ranged from 24.7 to 74.8%, and 15.7 to 53.4%, respectively. Independent variables such as districts, altitudes, and cultivar types were the most important variables that were significantly associated with the intensity of CBD in the study areas. Future research work should focus on conducting comprehensive epidemiological surveys, and the distribution of released and developing new CBD-resistant varieties to their specific agroecologies.

In Western Transdanubia in 2018 and in Central-Hungary in 2022 spiderwort plants showed flower breaking symptoms and mild mosaic on the foliage, which indicated a potential virus infection. One gram of symptomatic leaf sample was collected at both locations. Potyvirus-specific ELISA tests demonstrated potyvirus infection. To identify the virus species, potyvirus-specific RT-PCR was carried out on the samples. In both samples specific PCR products were detected and cloned into pGEM®-T Easy vector. The nucleotide sequences of the inserts were determined by Sanger sequencing. BLASTn searches on the complete coat protein region of both isolates demonstrated more than 99.87% identity with Tradescantia mild mosaic virus (TraMMV; accession number OL584375). Koch postulates were fulfilled by sap inoculating seed grown spiderwort plants. Phylogenetic analyses of the TraMMV coat protein sequences revealed two distinct evolutionary lineages: a tropical subgroup with at least 97.84% identity within the group and temperate subgroup with at least 98.97% identity within the group. One major difference between the subgroups was in the triplet responsible for vector transmission. The isolates belonging to the tropical subgroup had DAG triplets, while the temperate subgroup had NAG triplets. The difference in the triplets could be caused by natural diversification, directional selection or disruptive selection.

License: CC BY-NC-ND

The partitivirids feature an icosahedral protein coating accommodating both their dsRNA genome and RNA-dependent RNA polymerase (RdRP). This signifies that transcription and replication activities of the viral polymerase occur within the capsid, emphasizing that the viral cycle relies on polymerase incorporation. Particles lacking RdRP are defective and hence non-infectious. Encapsidation and replication are intricately linked for dsRNA viruses, to the extent that, for many of these, such as the cystovirids, the RdRP serves a dual role as a transcriptase/replicase and a pro-assembly factor, ensuring structural stability and overall capsid integrity. This work investigates if RdRP has a similar role within the capsid of Cannabis cryptic virus (CanCV), a betapartitivirus affecting Cannabis sativa. Utilizing reverse genetics in Nicotiana benthamiana, we conclusively established that RdRP expression is indispensable for CanCV’s virus-like particle formation. This study enhances our understanding of CanCV encapsidation, with RdRP serving a pivotal role as a pro-assembly factor. These preliminary findings contribute to the knowledge of viral assembly within the Partitiviridae family.

Plant resistances impose strong selective pressure on plant pathogen populations through the deployment of resistance genes, which leads to the emergence of new virulences. The pathogen adaptation also involves other parasitic fitness traits, especially aggressiveness components. A previous study on Puccinia triticina, the causal agent of wheat leaf rust, revealed that the distribution frequency of virulences in the French pathogen population cannot be fully explained by the major resistance genes deployed in the landscape. From 2012 to 2015, two dominant pathotypes (distinguished by their combination of virulences) were equally frequent despite the theoretical advantage conferred to one pathotype (166 317 0) by its virulence to Lr3, frequent in the cultivated landscape, whereas the other (106 314 0) is avirulent to this gene. To explain this apparent contradiction, we assessed three components of aggressiveness — infection efficiency, latency period and sporulation capacity — for 23 isolates representative of the most frequent genotype within each pathotype (106 314 0-G2 and 166 317 0-G1, identified by their combination of microsatellite markers). We tested these isolates on seedlings of Michigan Amber, a ‘naive’ wheat cultivar that has never been grown in the landscape, Apache, a ’neutral‘ cultivar with no selection effect on the landscape-pathotype pattern, and several cultivars that were frequently grown. We found that 106 314 0-G2 was more aggressive than 166 317 0-G1, with a consistency for the three components of aggressiveness. Our results show that aggressiveness plays a significant role in driving evolution in pathogen populations by acting as a selective advantage, even offsetting the disadvantage of lacking virulence towards a major Lr gene. Higher aggressiveness represents a competitive advantage that is likely even more pronounced when exhibited at the landscape scale as the expression of its multiple components is amplified by the polycyclic nature of epidemics.

This paper describes the experience of teaching plant pathology in Italy and traces the teaching environment over a period of more than 45 years, split into three main periods: 1975–2000; 2001–2020; and after 2020. The three periods are marked by different attitudes towards agriculture and, consequently, by a variable attractiveness of agricultural study programmes for students, as well as significant changes in the population of teachers and students. The teaching experience has been described by focusing on the changes that have taken place, from the perspectives of both students and teachers, all considered in an environment of continuous transformation. The changing importance of agriculture, the different approaches of people (consumers) towards agriculture, and how it has influenced students’ choices are considered. Data related to student enrolment at the College of Agriculture of the University of Turin have been used to provide real figures, which are useful to obtain a better understanding of the changes in the student population, also considering the different attractiveness of Agricultural Sciences, Forestry and Food Science, as well as the variations in the composition of the female student population, which increased from 28% in the late 1970’s to 38% in 2020. Female students now show the highest interest in Food Science Courses. The changes in the students and teachers’ backgrounds and attitudes, as well as in the teaching and learning methods are considered, and some critical considerations are drawn, also on the basis of the developed personal experience. Moreover, the effects of the Covid-19 pandemic disruption are discussed.