Main conclusion The findings of this study suggest that known resistant sorghum genotypes compensate for feeding pressure of sugarcane aphid by maintaining/increasing photosynthetic capacity and/or have higher chlorophyll content than susceptible genotypes. Abstract Knowledge of the physiological response of sorghum, ( Sorghum bicolor (L.) Moench), to sugarcane aphid (SCA), Melanaphis sacchari (Zehnter) feeding will provide baseline information on defense responses and resistance mechanisms. This study documented the impact of SCA feeding on seven sorghum genotypes by measuring chlorophyll content, photosynthetic rate, stomatal conductance, and carbon assimilation for a 14-d post-infestation evaluation. Carbon assimilation (A/Ci) curves were recorded at 3, 6, 9, and 15 d after aphid infestation to describe the pattern of physiological response of resistant and susceptible sorghums over time. Chlorophyll loss from resistant genotypes was significantly lower (≤ 10% loss) than from susceptible cultivars. Most resistant genotypes compensated for aphid feeding by either increasing or maintaining photosynthetic rate and stomatal conductance. Carbon assimilation curves over time showed that infested resistant plants had delayed photosynthetic decreases, whereas susceptible plants rapidly lost photosynthetic capacity. This research also investigated the influence of aphid density (0, 50, 100, and 200 nymphs/plant) on the photosynthetic rates of 28-d-old resistant and susceptible sorghums measured at 72-h post-infestation. Although there were no visual symptoms in susceptible sorghums, photosynthetic rates were impaired when infested with ≥ 100 SCA. In contrast, resistant plants were able to compensate for SCA feeding. Differences in the physiological responses of susceptible versus resistant sorghums indicate that resistant sorghum plants can tolerate some physiological impacts of SCA feeding and maintain photosynthetic integrity.

中文翻译：

---

高粱基因型对甘蔗蚜虫取食的差异反应

主要结论 本研究结果表明，已知抗性高粱基因型通过维持/增加光合能力和/或具有比易感基因型更高的叶绿素含量来补偿甘蔗蚜虫的摄食压力。摘要 了解高粱 (Sorghum bicolor (L.) Moench) 对甘蔗蚜 (SCA)、Melanaphis sacchari (Zehnter) 摄食的生理反应的知识将提供有关防御反应和抗性机制的基线信息。本研究通过测量叶绿素含量、光合速率、气孔导度和碳同化来记录 SCA 饲喂对 7 种高粱基因型的影响，用于 14 天的侵染后评估。碳同化 (A/Ci) 曲线分别记录在 3、6、9、和蚜虫侵染后 15 d，以描述抗性和易感高粱随时间的生理反应模式。抗性基因型的叶绿素损失显着低于易感品种的叶绿素损失（≤ 10%）。大多数抗性基因型通过增加或维持光合速率和气孔导度来补偿蚜虫的摄食。随着时间的推移，碳同化曲线表明，受侵染的抗性植物延迟了光合降低，而易感植物迅速失去了光合能力。这项研究还调查了蚜虫密度（0、50、100 和 200 只若虫/植物）对 28 天龄抗性和易感高粱在侵染后 72 小时测量的光合速率的影响。虽然易感高粱没有视觉症状，当感染 ≥ 100 SCA 时，光合速率受损。相比之下，抗性植物能够补偿 SCA 喂养。易感高粱和抗性高粱生理反应的差异表明，抗性高粱植物可以耐受 SCA 喂养的一些生理影响并保持光合完整性。