Flooding in Soybeans Induces Differential Transcriptional Responses Between Resistant and Susceptible Soybean Aphids (Aphis glycines)

Many plants possess defensive traits that enable them to naturally tolerate and/or deter insect herbivory (host plant resistance; HPR). Selecting for HPR traits can significantly enhance crop productivity by providing effective and sustainable insect pest management. Some insects have adapted to overcome these defenses (i.e. virulence), threatening the effectiveness, durability, and long-term adoption of HPR crops. Abiotic stressors associated with global climate change may modulate interactions between virulent and avirulent insects and their host plants. In some systems, abiotic stress reduces HPR efficacy and increase plant susceptibility to herbivory. Long-term, this could also favor insect adaptions to overcome HPR (i.e. virulence), although these evolutionary consequences have not been closely examined. To address this knowledge gap, we tested how one abiotic stressor, flooding, affects interactions between soybeans and the invasive, pestiferous soybean aphid (Aphis glycines). We used a full-factorial design with three experiment factors (8 treatment combinations): soybean aphid biotype (avirulent or virulent), soybean variety (susceptible or aphid-resistant), and host plant water stress (flooded or control). Each treatment combination had three biological replicates. Soybean aphid nymphs (<48 hours old) were allowed to feed for 12 hours, at which point they were removed and RNA sequencing analysis was performed to compare changes in aphid gene expression under different host plant stress combinations.

多数植物均拥有防御性状，可使其天然耐受并/或抵御昆虫取食（寄主植物抗性（Host Plant Resistance，HPR））。针对寄主植物抗性性状进行选育，可通过提供高效且可持续的害虫防控手段，显著提升作物产量。部分昆虫已演化出突破此类防御的能力（即毒力（virulence）），这会威胁到寄主植物抗性作物的防控效果、持效性与长期推广应用。与全球气候变化相关的非生物胁迫，可能会调控毒力型与无毒力型昆虫与其寄主植物之间的互作关系。在部分研究体系中，非生物胁迫会降低寄主植物抗性的效力，并提升植物对昆虫取食的易感性。从长期来看，这也可能会助力昆虫演化出突破寄主植物抗性的能力（即毒力），尽管此类进化效应尚未得到深入探究。为填补这一研究空白，我们探究了非生物胁迫因子之一——淹涝——如何影响大豆与入侵性害虫大豆蚜（Aphis glycines）之间的互作关系。本研究采用全因子实验设计，设置3个实验因子、共8种处理组合：大豆蚜生物型（无毒力型或毒力型）、大豆品种（感蚜型或抗蚜型）以及寄主植物水分胁迫（淹涝组或对照组）。每种处理组合均设置3次生物学重复。取12小时龄以下的大豆蚜若虫进行取食实验，时长为12小时后移除蚜虫，随后开展RNA测序（RNA sequencing）分析，以对比不同寄主植物胁迫组合下蚜虫的基因表达变化。