نوع مقاله : علمی پژوهشی-فارسی
نویسندگان
1 دانشیار گروه گیاه‌پزشکی، دانشکده کشاورزی، دانشگاه یاسوج، یاسوج، ایران
2 استادیار، بخش تحقیقات گیاه‌پزشکی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان کهگیلویه و بویراحمد، سازمان تحقیقات، آموزش و ترویج کشاورزی، یاسوج، ایران
3 کارشناسی ارشد، سازمان جهاد کشاورزی استان کهگیلویه و بویراحمد، یاسوج، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objectives
Pseudomonas syringae pv. syringae (Pss) poses a significant threat to agricultural ecosystems due to its broad host range, encompassing over 200 plant species. Disease-causing bacteria infect all aboveground plant organs throughout the season, causing symptoms such as fruit spots, necrosis, dead buds, flower blight, and cankers on stems and branches. The control of diseases caused by Pss is almost impossible because of the lack of effective chemical or biocontrol agents, the low number of resistant cultivars and the endophytic nature of the pathogen. Different pathogenic strains have a large genetic variability adaptable to different hosts, cultivars, and pedoclimatic conditions, making it difficult to control bacterial canker. One of the most viable and economical methods for managing bacterial canker in peaches is to use resistant cultivars. The present study aims to determine the resistance reactions of peach cultivars against Pss.
Materials and Methods
During 2016-2018, bacterial strains were isolated from stone fruit plants with leaf spot, canker, and gummosis symptoms. Physiological, biochemical, and molecular tests were performed on all isolated strains. To evaluate the resistance of peach cultivars, Pss was inoculated to two-year-old seedlings of different peach cultivars, including Zaferani, Alberta, Anjiri, and Hastejoda. Different pairs of primers were used to detect virulence genes in Pss isolates.
Results
Isolates were rod-shaped, motile, gram-negative, obligate aerobe, oxidase negative, catalase, levan and tobacco hypersensitive reaction positive, arginine dihydrolase, and potato rot negative. Additionally, all isolates harbored the genes responsible for syringomycin synthesis (syrB) and syringomycin secretion (syrD). Based on these phenotypic and genotypic characteristics, along with the results of pathogenicity tests and PCR analysis, all isolates were identified as Pss. Various primers were used to detect important virulence genes in different Pss isolates. The syringomycin synthesis gene (syrB) was detected in all Pss isolates. The sypA gene was detected in Pss strains H2, H3, H4, and H5, and the sypB gene was detected in Pss strains H2, H34, H5, and G1.
Moreover, nit gene was detected in H4 and H5 isolates, and ach gene was detected in strains H1, H2, and H4. Pss strains H3, H4, and H5 produced the expected 1128 bp product after amplification with hrmA1 and hrmA2 primers. Four cultivars, namely Alberta, Zaferani, Hastejoda, and Anjiri, were chosen for the study to investigate the resistance of peach plants. Significant variations were observed among the different cultivars regarding the number of necrotic lesions on the leaves and the length of the necrotic regions on the branches. Among the cultivars examined, Anjiri showed the highest susceptibility to Pss, while Hastejoda exhibited the least sensitivity, indicating potential resistance to the pathogen.
Discussion
Besides its usage for fresh fruit, canned fruit, dried fruit snacks, and fruit juice, peach trees are considered ornamental plants attributed of their white, pink, or red flowers during springtime. Commercial peach production is challenging for multiple reasons. One of them involves its susceptibility to many diseases that can significantly affect fruit yield and quality, and some can also impact the longevity of the trees. The enormous efforts carried out over the last two decades have led us to gain a more in-depth understanding of the P. syringae pv. syringae-host interactions. In Iran, there are no effective treatments for controlling bacterial canker of stone fruits caused by Pseudomonas syringae pv. syringae. Host tolerance to plant pathogens is important for developing cost-effective and environmentally safe strategies for disease management. Similarly, using resistant cultivars in crop improvement is critical since plants and plant products are usually protected from, rather than cured, diseases. Resistant genotypes will allow sustainable control with zero pesticide residues on fruits, improving the safety of harvesting and decreasing disease problems during storage, thereby leading to enhanced economic benefits.
کلیدواژه‌ها [English]
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