内共生菌Buchnera协助蚜虫抑制寄主植物的防御反应

为明确蚜虫内共生细菌Buchnera能否协助蚜虫抑制植物的防御反应，采用混合抗生素除去瓜蚜Aphis gossypii体内的Buchnera，采用刺吸电位技术和生命表方法比较除菌瓜蚜和正常瓜蚜在黄瓜上的适合度，并测定被除菌瓜蚜和正常瓜蚜预侵染黄瓜叶片中H₂O₂、茉莉酸和水杨酸的含量变化以及抗蚜特性变化。结果表明，除菌瓜蚜体重较正常瓜蚜极显著下降了71.15%，净增殖率极显著下降了95.60%，但寿命延长了2.34倍；刺吸电位图谱显示除菌瓜蚜几乎不产生代表唾液分泌的E1波和韧皮部被动吸食的E2波。在黄瓜叶片中，除菌瓜蚜比正常瓜蚜能激发产生更高水平的H₂O₂；在为期14 d的侵染中，除菌瓜蚜侵染诱发总茉莉酸含量持续升高、总水杨酸含量持续下降，而正常瓜蚜侵染诱发总茉莉酸含量先升高后降低、总水杨酸含量先降低后升高。在被除菌瓜蚜预侵染黄瓜上，瓜蚜进入稳定取食的时间显著滞后于正常瓜蚜预侵染处理，且前3 d的产蚜量显著低于正常瓜蚜预侵染处理。表明Buchnera除了可为蚜虫提供必需的营养外，还有调控和抑制寄主植物防御反应的功能。

Aphid endosymbiont Buchnera assists the aphid in inhibiting plant defenses

To investigate whether the aphid endosymbiont Buchnera assists aphids in inhibiting plant defenses, a mixture of antibiotics was used to remove Buchnera of cucurbit-specialized biotype of Aphis gossypii, assessed the fitness of antibiotic-treated aphids on cucumbers, as well as the defensive substances and susceptibility of cucumbers infested by these antibiotic-treated aphids. The results revealed a 71.15% decrease in body weight and a 95.60% decrease in fecundity in the antibiotic-treated aphids compared to normal aphids, but their lifespan increased by 2.34 folds. The electrical penetration graph showed that the antibiotic-treated aphids produced nearly no E1 and E2 waveforms, reflecting phloem salivation and phloem sap ingestion, respectively. Furthermore, the antibiotic-treated aphids stimulated higher levels of H₂O₂ compared to untreated aphids. Over a 14-d infestation, the antibiotic-treated aphids exhibited a continuous increase in total jasmonic acid and a continuous decrease in total salicylic acid, while untreated aphids showed an initial rise in total jasmonic acid followed by a decrease and an initial decrease in total salicylic acid followed by an increase. The duration from contacting to stable feeding significantly prolonged, and fecundity in the first three days significantly decreased for aphids on cucumbers that were previously infested by antibiotic-treated aphids. These results indicate that, in addition to providing necessary nutrients for aphids, Buchnera also play a role in assisting aphids in suppressing host plant defenses.