Ahmed Eman A, Farrag Amro A, Kheder Ahmed A, Shaaban Ahmed
Virus and Phytoplasma Research Department, Plant Pathology Research Institute, Agricultural Research Center, Giza 12619, Egypt.
Agronomy Department, Faculty of Agriculture, Fayoum University, Fayoum 63514, Egypt.
Plants (Basel). 2022 Feb 10;11(4):477. doi: 10.3390/plants11040477.
Phytoplasmas are obligate cell-wall-less plant pathogenic bacteria that infect many economically important crops, causing considerable yield losses worldwide. Very little information is known about phytoplasma-host plant interaction mechanisms and their influence on sesame yield and oil quality. Therefore, our aim was to explore the ultrastructural and agro-physio-biochemical responses of sesame plants and their effects on sesame productivity and oil quality in response to phytoplasma infection. Sesame leaf samples exhibiting phyllody symptoms were collected from three experimental fields during the 2021 growing season. Phytoplasma was successfully detected by nested- polymerase chain reaction (PCR) assays using the universal primer pairs P1/P7 and R16F2n/R16R2, and the product of approximately 1200 bp was amplified. The amplified product of 16S rRNA was sequenced and compared with other available phytoplasma's 16S rRNA in the GenBank database. Phylogenetic analysis revealed that our Egyptian isolate under accession number MW945416 is closely related to the 16SrII group and showed close (99.7%) identity with MH011394 and L33765.1, which were isolated from Egypt and the USA, respectively. The microscopic examination of phytoplasma-infected plants revealed an observable deterioration in tissue and cell ultrastructure. The primary and secondary metabolites considerably increased in infected plants compared with healthy ones. Moreover, phytoplasma-infected plants showed drastically reduced water content, chlorophyll content, growth, and yield components, resulting in 37.9% and 42.5% reductions in seed and oil yield, respectively. The peroxide value of the infected plant's oil was 43.2% higher than that of healthy ones, suggesting a short shelf-life. Our findings will provide a better understanding of the phyllody disease pathosystem, helping us to develop effective strategies for overcoming such diseases.
植原体是一类专性无细胞壁的植物病原细菌，可感染许多具有重要经济价值的作物，在全球范围内造成相当大的产量损失。关于植原体与寄主植物的相互作用机制及其对芝麻产量和油品质的影响，人们了解甚少。因此，我们的目的是探究芝麻植株对植原体感染的超微结构以及农业生理生化反应，及其对芝麻生产力和油品质的影响。在2021年生长季，从三个试验田中采集了表现出叶变症状的芝麻叶片样本。使用通用引物对P1/P7和R16F2n/R16R2，通过巢式聚合酶链反应（PCR）检测成功检测到植原体，并扩增出约1200 bp的产物。对16S rRNA的扩增产物进行测序，并与GenBank数据库中其他可用的植原体16S rRNA进行比较。系统发育分析表明，我们登录号为MW945416的埃及分离株与16SrII组密切相关，与分别从埃及和美国分离的MH011394和L33765.1显示出密切的（99.7%）同一性。对感染植原体的植物进行显微镜检查发现，组织和细胞超微结构出现明显恶化。与健康植株相比，感染植株中的初级和次级代谢产物显著增加。此外，感染植原体的植株水分含量、叶绿素含量、生长和产量构成因素大幅降低，种子产量和油产量分别降低了37.9%和42.5%。感染植株油的过氧化值比健康植株高43.2%，表明其保质期较短。我们的研究结果将有助于更好地理解叶变病病理系统，帮助我们制定有效的策略来克服此类疾病。
