Key Laboratory of National Forestry & Grassland Administration on Forest Resources Conservation and Ecological Safety in the Upper Reaches of the Yangtze River, College of Forestry, Sichuan Agricultural University, 611130 Chengdu, China.
Key Laboratory of National Forestry & Grassland Administration on Forest Resources Conservation and Ecological Safety in the Upper Reaches of the Yangtze River, College of Forestry, Sichuan Agricultural University, 611130 Chengdu, China; College of Resources and Environmental Engineering, Sichuan Water Conservancy College, 611231 Chongzhou, China.
Sci Total Environ. 2022 Nov 1;845:157171. doi: 10.1016/j.scitotenv.2022.157171. Epub 2022 Jul 7.
Drought stress poses adverse influence on plant growth and further alters plant-herbivore interactions. Such effect is enhanced as drought occurrence is reported to increase due to global warming. Although dioecious plant species have shown sex-specific response to drought stress through the changes in growth performance and stress tolerance, whether such changes will drive sex-specific differences in defense against herbivores between male and female plant conspecifics is barely studied. In the current study, female and male poplar full-siblings were submitted to moderate (75 % field water capacity) and severe drought (50 % field water capacity) stresses, followed by herbivore growth and feeding bioassays to test the effect of plant gender on herbivore growth and feeding performance of two specialist and two generalist leaf herbivores. The results showed that although the growth of both plant sexes was inhibited by the two drought levels, male plants performed better than female conspecifics. In the paired-choice bioassays, the specialist herbivores preferred female plants while the generalist herbivores fed more on the male plants without drought stress. Both the moderate and severe drought stresses reversed such preferences. In the triple-choice bioassays, the specialist herbivores preferred female control plants while the generalist herbivores fed more on female plants under severe drought. In addition, the specialist herbivores fed on female plants from severe drought stress grew the worst while the generalist herbivores gained the highest fresh weight. The transcriptomic and metabolomic profiling revealed that female plant leaves contained higher levels of flavonoids than males under control condition while severe drought stress remarkably reduced the levels of defensive metabolites such as flavonoids, isoflavonoids, neoflavonoids and alkaloids in female but not in male plant leaves.
干旱胁迫对植物生长有不利影响，并进一步改变植物-食草动物的相互作用。由于全球变暖，据报道干旱的发生有所增加，这种影响会加剧。尽管雌雄异株植物通过生长性能和胁迫耐受性的变化表现出对干旱胁迫的性别特异性响应，但这种变化是否会导致雄性和雌性同种植物之间防御食草动物的性别特异性差异，几乎没有研究。在本研究中，雌性和雄性杨树全同胞被置于中度（田间持水量的 75%）和重度干旱（田间持水量的 50%）胁迫下，然后进行食草动物生长和取食生物测定，以测试植物性别对两种专食性和两种广食性叶食草动物生长和取食性能的影响。结果表明，尽管两种干旱水平都抑制了植物两性的生长，但雄性植物的表现优于雌性同系物。在配对选择生物测定中，专食性食草动物更喜欢雌性植物，而广食性食草动物在没有干旱胁迫的情况下更喜欢雄性植物。中度和重度干旱胁迫都逆转了这种偏好。在三重选择生物测定中，专食性食草动物更喜欢对照雌性植物，而广食性食草动物在重度干旱下更喜欢雌性植物。此外，专食性食草动物在重度干旱胁迫下取食雌性植物生长最差，而广食性食草动物获得的鲜重最高。转录组和代谢组分析表明，在对照条件下，雌性植物叶片中的类黄酮水平高于雄性，而重度干旱胁迫显著降低了雌性植物叶片中防御性代谢物（如类黄酮、异黄酮、新黄酮和生物碱）的水平，但雄性植物叶片中没有。
