College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China.
BMC Plant Biol. 2019 Nov 25;19(1):514. doi: 10.1186/s12870-019-2116-0.
Plant defense against herbivores begins with perception. The earlier plant detects the harm, the greater plant will benefit in its arm race with the herbivore. Before feeding, the larvae of the rice pest Cnaphalocrocis medinalis, initially spin silk and fold up a leaf. Rice can detect and protect itself against C. medinalis feeding. However, whether rice could perceive C. medinalis leaf rolling behavior is currently unknown. Here, we evaluated the role of leaf rolling by C. medinalis and artificial leaf rolling in rice plant defense and its indirect effect on two important C. medinalis parasitoids (Itoplectis naranyae and Apanteles sp.) through a combination of volatile profiling, gene-transcriptional and phytohormonal profiling.
Natural leaf rolling by C. medinalis resulted in an increased attraction of I. naranyae when compared to the undamaged plant after 12 h. Volatile analysis revealed that six out of a total 22 components significantly increased in the headspace of C. medinalis rolled plant when compared to undamaged plant. Principal component analysis of these components revealed similarities in the headspace of undamaged plant and artificially rolled plant while the headspace volatiles of C. medinalis rolled plant deferred significantly. Leaf rolling and feeding by C. medinalis up-regulated the plant transcriptome and a series of jasmonic acid (JA) and salicylic acid (SA) related genes. While feeding significantly increased JA level after 12 to 36 h, rolling significantly increased SA level after 2 to 12 h. Compared to artificial rolling, natural rolling significantly increased JA level after 36 h and SA level after 2 and 12 h.
Our findings suggest that natural leaf rolling by C. medinalis can be perceived by rice plant. The detection of this behavior may serve as an early warning signal in favor of the rice plant defenses against C. medinalis.
植物对草食动物的防御始于感知。植物越早发现伤害，它在与草食动物的军备竞赛中就越受益。在取食之前，水稻害虫二化螟的幼虫最初会吐丝并将一片叶子折起来。水稻可以检测到并保护自己免受二化螟的侵害。然而，水稻是否能感知二化螟的卷叶行为目前尚不清楚。在这里，我们通过挥发物分析、基因转录和植物激素分析，结合二化螟自然卷叶和人工卷叶对水稻植物防御的作用及其对两种重要二化螟寄生蜂（稻绿蝽和 Apanteles sp.）的间接影响进行了评估。
与未受损植株相比，12 小时后，二化螟自然卷叶导致稻绿蝽的吸引力增加。挥发物分析显示，与未受损植株相比，二化螟卷叶植株的头部分离出的 22 种成分中有 6 种显著增加。对这些成分的主成分分析表明，未受损植株和人工卷叶植株的头部分离物相似，而二化螟卷叶植株的头部分离物明显不同。二化螟卷叶和取食显著上调了植物的转录组和一系列茉莉酸（JA）和水杨酸（SA）相关基因。取食后 12 至 36 小时 JA 水平显著增加，而卷叶后 2 至 12 小时 SA 水平显著增加。与人工卷叶相比，二化螟自然卷叶后 36 小时 JA 水平显著增加，2 小时和 12 小时 SA 水平显著增加。
我们的研究结果表明，二化螟的自然卷叶可以被水稻植株感知。这种行为的检测可能是水稻植物对二化螟防御的早期预警信号。
