Sobhy Islam S, Miyake Atsushi, Shinya Tomonori, Galis Ivan
Institute of Plant Science and Resources (IPSR), Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, 710-0046, Japan.
Department of Plant Protection, Public Service Center of Biological Control (PSCBC), Faculty of Agriculture, Suez Canal University, Ismailia, 41522, Egypt.
J Chem Ecol. 2017 Sep;43(9):929-943. doi: 10.1007/s10886-017-0882-4. Epub 2017 Aug 31.
Plants synthesize variable mixtures of herbivore-induced plant volatiles (HIPVs) as part of their evolutionary conserved defense. To elucidate the impact of chewing herbivores with different level of adaptation on HIPV profiles in rice, we measured HIPVs released from rice seedlings challenged by either the generalist herbivore Mythimna loreyi (MYL) or the specialist Parnara guttata (PAG). Both herbivores markedly elicited the emission of HIPVs, mainly on the second and third days after attack compared to control plants. In addition, side-by-side HIPV comparisons using MYL and PAG caterpillars revealed that generalist feeding induced comparably more HIPVs relative to specialist, particularly on day two as highlighted by multivariate analysis (PLS-DA) of emitted HIPVs, and further confirmed in mimicked herbivory experiments. Here, mechanically wounded plants treated with water (WW) released more VOCs than untreated controls, and on top of this, oral secretions (OS) from both herbivores showed differential effects on volatile emissions from the wounded plants. Similar to actual herbivory, MYL OS promoted higher amounts of HIPVs relative to PAG OS, thus supporting disparate induction of rice indirect defenses in response to generalist and specialist herbivores, which could be due to the differential composition of their OS. (196 words).
植物合成多种由食草动物诱导产生的植物挥发物（HIPVs）混合物，作为其进化保守防御机制的一部分。为了阐明不同适应水平的咀嚼式食草动物对水稻中HIPV谱的影响，我们测量了受多食性食草动物粘虫（MYL）或专食性直纹稻弄蝶（PAG）攻击的水稻幼苗释放的HIPVs。与对照植株相比，这两种食草动物均显著引发了HIPVs的释放，主要在攻击后的第二天和第三天。此外，使用MYL和PAG毛虫进行的HIPV并列比较显示，相对于专食性动物，多食性动物取食诱导产生的HIPVs相对更多，特别是在第二天，这一点通过对释放的HIPVs进行多变量分析（PLS-DA）得到突出显示，并在模拟食草实验中得到进一步证实。在这里，用水处理的机械损伤植株（WW）比未处理的对照释放出更多的挥发性有机化合物（VOCs），除此之外，两种食草动物的口腔分泌物（OS）对损伤植株的挥发性排放显示出不同的影响。与实际食草情况类似，相对于PAG的OS，MYL的OS促进产生了更多的HIPVs，从而支持了水稻对多食性和专食性食草动物的间接防御存在差异诱导，这可能是由于它们OS的组成不同所致。
