Journal of Plant Pathology最新文献

Root rot is a destructive soil-borne disease of Coptis chinensis, which depends on chemical control at present, and more attention should be paid to biocontrol of disease. In the present research, isolate Y9 isolated from healthy root samples of Coptis, was identified as Bacillus cereus. Further screening and pot experiments showed that B. cereus isolate Y9 inhibited the growth of the main causal agents of coptis root rot disease (Fusarium solani and F. avenaceum) and seven other phytopathogenic fungi. The application of B. cereus isolate Y9 and compatible Trichoderma harzianum, T. atroviride and B. amyloliquefaciens, singly and in combination were found to be effective against Fusarium root rot in vitro and in field experiments. In field experiments, combinations of T. harzianum + B. amyloliquefaciens + Y9 (HYJ, in ratio of 1:1:1) showed the highest control efficacy of 63.85%, which was higher than the expected value (53.18%), indicating synergistic effect on the control of coptis root rot. Therefore, B. cereus isolate Y9 may be a potential biological control agent, and combined use with T. harzianum and B. amyloquefaciens offered even greater potential. The long-term effects of isolate B. cereus Y9 and its combinations on C. chinensis should be assessed in different locations and seasons in the future.

Tomato yellow leaf curl disease (TYLCD) and tomato leaf curl disease (TLCD) cause serious losses in tomato production, especially in tropical and sub-tropical regions. In 2014–2015, tomato samples with TYLCD/TLCD-like symptoms were collected from different provinces of Iraq and infection with tomato yellow leaf curl virus (TYLCV) identified. To study the diversity of TYLCV, DNA of eight positive samples from this survey was used for rolling-circle amplification, cloning and sequencing. Pairwise nucleotide sequence comparisons with complete genomes showed that the Iraqi TYLCV isolates belonged to the strains TYLCV-IL and TYLCV-Mld. In a phylogenetic analysis, the Iraqi TYLCV-IL isolates grouped into three distinct clades, consisting of TYLCV-IL (A) and the two new variants TYLCV-IL (D) and TYLCV-IL (E). The Iraqi isolate of TYLCV-Mld grouped into the newly proposed TYLCV-Mld (D) variant. For one sample, sequencing also revealed co-infection with tomato leaf curl Palampur virus (ToLCPalV). The phylogenetic tree of ToLCPalV DNA-A showed a close relationship between the isolates of different hosts from Iraq and Iran. No evidence of recombination was detected in ToLCPalV DNA-A, but recombination was observed for the TYLCV isolates. The results indicate that there is a high diversity of TYLCV in Iraq, including new variants, that is partly shared with Kuwait and countries in the Eastern Mediterranean Region. Occurrence of multiple TYLCV variants and ToLCPalV can act as a potential threat to tomato production in Iraq.

Ascomycete fungi isolated in Central Siberia from canker lesions of Abies sibirica Ledeb. were assigned to the genus Corinectria Gonzalez & Chaverri. Our earlier research has shown four Corinectria Siberian strains to be significantly different genetically from the known Corinectria spp. This work investigated the secondary metabolites of 23 morphologically similar Corinectria Siberian strains and their phytotoxicity. The strains were divided into two types by their morphological and cultural traits, MCT1 and MCT2. The MCT1 strains synthesized the meroterpenoids ilicicolins A and B, ilicicolin A epoxide and chlorocylindrocarpol; the MCT2 strains produced ilicicolins C, D (ascochlorin), F and ascofuranol. The phytotoxicity of the Corinectria strains showed a significant heterogeneity to Picea obovata seeds and was exhibited by 31% of the MCT1 strains and 50% of the МСТ2 strains. The more phytotoxic strains had an inhibitory effect on A. sibirica calluses. Ilicicolins C, D, and F synthesized by the MCT2 strains significantly inhibited the growth processes of both A. sibirica seedlings and Pinus sibirica Du Tour saplings.

Durum wheat is among the cereal crops with the highest susceptibility to Fusarium Head Blight (FHB), the most devastating wheat disease. Purple pericarp durum wheat genotypes, having anthocyanin-rich grains, are an unexplored group of accessions, which may provide valuable information about the role of flavonoids in wheat-Fusarium interaction. In this study, a purple pericarp durum wheat accession (Purple durum) was challenged with Fusarium graminearum infection, evaluating the different responses of physiological traits, in comparison with an FHB-resistant line (DBC-480) and a commercial FHB-susceptible cultivar (Svevo). Purple durum showed high susceptibility to FHB, but the infection did not affect the seed set, as for the resistant control. In Purple durum flag leaves, lower flavonoid content and higher temperature depression, compared to the resistant control, were detected. The infection affected the difference between the spike temperature and the flag leaf temperature in the resistant and the susceptible control in an opposite way, while the total phenolic content was always higher in the infected spikes. Instead, the total anthocyanin content (TAC) of the spikes was considerably lower in Purple durum subjected to the infection compared to the mock plants, while TAC increased in the infected resistant genotype, suggesting an involvement of anthocyanins in the resistance mechanism of DBC-480. Association among morphological spike traits and physiological traits are discussed. Our results corroborate the importance of phenylpropanoids in FHB-wheat interaction and point attention on anthocyanin metabolism, suggesting to further consider these metabolites, which are under-investigated for durum wheat resistance.

A greater genetic diversity is essential for disease resistance in particular, and intergeneric hybridization makes this possible. The genus Cydomalus (syn: Cydolus), which is frequently used as rootstock, was derived from intergeneric hybridization between Cydonia oblonga Mill. and Malus domestica Borkh in Moldova and Bulgaria. It is known that hybrids from this genus exhibit quince and/or apple characteristics and some of them have been identified with reddish fruit skin color in Türkiye in the last decade. Erwinia amylovora Burril. is the most devastating bacterial disease in the Rosaceae family, and there have been no reports of Cydomalus. In this study, fire blight susceptibility index of three Cydomalus genotypes, were collected from İzmir and Manisa provinces, and two important quince rootstocks were determined by artificial inoculations with the most virulent Erwinia amylovora strain of our collection, under greenhouse conditions for two consecutive years. In addition, susceptibility levels of two Cydomalus genotypes were observed under natural disease pressure habitats. In line with the results of artificial inoculations, two of Cydomalus genotypes were determined to be more tolerant to fire blight disease than quince rootstocks and these genotypes could be used in breeding studies. Moreover, Cydomalus genus was identified as the new host for Erwinia amylovora.

Trend in the reduction on use of synthetic pesticides is continuously growing. Their substitution with natural substances is well studied because of the environmental vantages. Consumers require safe foods. Their risk perception concerns the presence of synthetic pesticides and marketing is oriented toward food with lower and lower residue levels. Essential oils (EOs) could be a reliable alternative. Their components are in a variable range of concentrations determining, in some cases, for the chemotypes. Lots of rosemary, oregano, and clove oil were purchased on the market and their main components were analyzed. Four EOs formulations were prepared to test their effectiveness against zucchini powdery mildew. Moreover, rosemary leaves were collected from the CREA-DC garden (Rome) and rosemary essential oil, distilled in-house, in combination with oregano essential oil were also tested. Metrafenone and penconazole were synthetic fungicides used for reference treatments. Two trials were carried out in a greenhouse.

Raspberry (Rubus idaeus L.) is a crop with increasing commercial value due to its nutritional properties and demand in national and international markets. Throughout the growing process, there have been reports of the presence of galls on roots and stems, which reduce plant size and yields. The current study used phylogenetic reconstruction to identify bacteria associated with these symptoms in raspberry plantations in the Mexican states of Jalisco and Michoacán. A total of 69 representative strains selected according to their colony morphotype were identified based on partial sequencing of the 16S ribosomal gene. Forty-nine of them were tested for pathogenicity, including of which three strains induced gall symptoms in raspberry and tomato plants. A set of 28 strains identified within the Agrobacterium and Rhizobium genera were chosen for amplification of the atpD, glnA, gyrB, and rpoB genes. Strain CPO 2.419 was selected for whole genome sequencing, with a total length of 5,679,921 base pairs assembled into 46 contigs. This strain was identified as A. tumefaciens (GenBank JAVIYJ000000000.1) using phylogenetic reconstruction. According to the OrthoANIu and dDDH percentage values, the CPO 2.419 strain belongs to the A. tumefaciens complex, along with the closely related strains of A. tumefaciens LMG 232 (99.4, 89.1), A. tumefaciens CNPSo 675 (98.5, 84.8), and A. tumefaciens ATCC 4720^T (98.1, 78), respectively. This study contributes to the understanding of the genomic Agrobacterium diversity in raspberry-producing areas in Mexico and highlights the relevance of genomics for accurate bacterial identification, with important implications for agriculture.

Wheat (Triticum aestivum L.) is an important food crop throughout the world. The seed mycobiome is the primary inoculum affecting the overall health and productivity of wheat plants. Seed-borne fungi can have an impact on the production of wheat and cause health complications upon consumption. Therefore, for durable and sustainable wheat production, it is imperative to characterise the wheat mycobiome. The rationale of this study was to investigate the wheat seed mycobiome of two Egyptian wheat cultivars (Sids 14 and Giza 171) using a culture-independent technique. The fungal community in 6 wheat seed samples was identified by high-throughput amplicon sequencing of the ITS2 region using the Illumina MiSeq platform. A total of 162 genera, 111 families, 55 orders and 25 classes have been identified. The fungal communities detected varied between seed samples, with a higher abundance of Ascomycota followed by Basidiomycota. Potential beneficial and pathogenic genera could be detected. Interestingly, a higher abundance of Vishniacozyma, Epicoccum, Cladosporium, Blumeria, Stymphylium, Fusarium, Filobasidium, and Alternaria was observed in the samples. Both Anthracocystis and Nigrospora were detected exclusively in T. aestivum cv. Giza 171. These results open new avenues for further investigation on the role of the mycobiome in Egyptian wheat cultivars. Ultimately, precise identification of both beneficial and pathogenic fungal genera could be accomplished.

Xanthomonas oryzae pv. oryzae is a destructive bacterial disease of rice. Due to the development of resistance by the existing bactericides, an alternative eco-friendly management strategy should be identified to contain the disease. The present study focused on the efficacy of salicylic acid (SA) and their metabolically active biomolecules against X. oryzae pv. oryzae during their interaction. The biofilm inhibition clearly expressed the aggregation, separation and presence of dead cells at various concentrations of SA. The highest biofilm production was observed for untreated control with maximum O.D. value. There is a significant difference in their O.D. values on the concentrations of SA. While studying the inhibition percentages, the chloramphenicol @ 0.2% recorded the highest percentage (76.65%) which shows significant results with SA at 250 ppm (75.56) followed by 100 and 50 ppm which exhibited no significant differences in their inhibition percentages (65.78% and 45.74%, respectively). Under CLSM the Xoo cell aggregation and separation has been observed at 50 ppm and 100 ppm and diminished at 250 ppm respectively. Under in silico analysis, the biomolecules from SA, viz., tetradecanoic acid, methyl oleate, and decyl acrylate, were extracted with a higher area percentage against Xoo target proteins with chloramphenicol as a positive control. Tetradecanoic acid has the highest -C DOCKER energy of 39.46 kcal/mol with the effector proteins of Xoo. The docked metabolites, were subjected to in planta assays, among them tetradecanoic acid recorded minimum lesion size of 0.6 cm at 5000 ppm followed by decyl acrylate (1.5 cm).Our results suggest that overexpression of NPR 1, PAL and LOX has been documented at SA at 250 ppm which can be used to improve BLB resistance in rice. The present study concludes that salicylic acid plays a signalling role inhibition of Xoo biofilm, a source of biomolecules, activation of various plant defence responses against Xoo.