Table_3_Global Responses of Resistant and Susceptible Sorghum (Sorghum bicolor) to Sugarcane Aphid (Melanaphis sacchari).XLSX

The sugarcane aphid (Melanaphis sacchari) has emerged as a significant pest for sorghum. The use of sugarcane aphid-resistant sorghum germplasm with integrated pest management strategies appears to be an excellent solution to this problem. In this study, a resistant line (RTx2783) and a susceptible line (A/BCK60) were used to characterize the differences in plant responses to the sugarcane aphid through a series of experiments, which examined global sorghum gene expression, aphid feeding behavior and inheritance of aphid resistance. The global transcriptomic responses to sugarcane aphids in resistant and susceptible plants were identified using RNA-seq and compared to the expression profiles of uninfested plants at 5, 10, and 15 days post-infestation. The expression of genes from several functional categories were altered in aphid-infested susceptible plants, which included genes related to cell wall modification, photosynthesis and phytohormone biosynthesis. In the resistant line, only 31 genes were differentially expressed in the infested plants relative to uninfested plants over the same timecourse. However, network analysis of these transcriptomes identified a co-expression module where the expression of multiple sugar and starch associated genes were repressed in infested resistant plants at 5 and 10 days. Several nucleotide-binding-site, leucine-rich repeat (NBS-LRR) and disease resistance genes similar to aphid resistance genes identified in other plants are identified in the current study which may be involved in sugarcane aphid resistance. The electrical penetration graph (EPG) results indicated that sugarcane aphid spent approximately twice as long in non-probing phase, and approximately a quarter of time in phloem ingestion phase on the resistant and F1 plants compared to susceptible plant. Additionally, network analysis identified a phloem protein 2 gene expressed in both susceptible and resistant plants early (day 5) of infestation, which may contribute to defense against aphid feeding within sieve elements. The resistant line RTx2783 displayed both antixenosis and antibiosis modes of resistance based on EPG and choice bioassays between susceptible, resistant and F1 plants. Aphid resistance from RTx2783 segregated as a single dominant locus in the F2 generation, which will enable breeders to rapidly develop sugarcane aphid-resistant hybrids using RTx2783 as the male parent.

甘蔗蚜虫（Melanaphis sacchari）已成为高粱的重要害虫。采用具有集成病虫害管理策略的甘蔗蚜虫抗性高粱种质资源，似乎是对此问题的一个绝佳解决方案。在本研究中，通过一系列实验，我们利用一个抗性系（RTx2783）和一个易感系（A/BCK60）来表征植物对甘蔗蚜虫的反应差异，实验内容包括高粱基因表达的全景分析、蚜虫取食行为及蚜虫抗性的遗传。利用RNA测序技术，确定了抗性植物和易感植物对甘蔗蚜虫的全球转录组反应，并将其与5、10和15天后未感染植物的基因表达谱进行了比较。在受蚜虫侵害的易感植物中，多个功能类别中的基因表达发生了改变，包括与细胞壁修饰、光合作用和植物激素生物合成相关的基因。在抗性系中，相对于未受侵害的植物，在相同的时间进程中，只有31个基因的表达发生了差异。然而，通过转录组网络分析，识别出一个共表达模块，其中在受蚜虫侵害的抗性植物中，多个与糖和淀粉相关的基因在5天和10天时被抑制。本研究中鉴定出与在其他植物中发现的蚜虫抗性基因相似的核苷酸结合位点、富含亮氨酸的重复（NBS-LRR）和抗病基因，这些基因可能参与了甘蔗蚜虫的抗性。电穿孔图（EPG）结果显示，与易感植物相比，甘蔗蚜虫在抗性和F1植物的非探测阶段停留的时间大约是两倍，在韧皮部摄取阶段停留的时间大约是四分之一。此外，网络分析还发现，在侵害早期（第5天），易感植物和抗性植物中都表达了一种韧皮蛋白2基因，该基因可能有助于筛管内对蚜虫取食的防御。根据EPG和选择生物试验的结果，抗性系RTx2783表现出抗避性和抗生性两种抗蚜虫模式。RTx2783的抗蚜虫基因在F2代中作为一个单显性位点分离，这将使育种者能够快速利用RTx2783作为父本亲本，开发出抗甘蔗蚜虫的杂交种。