International Centre of Insect Physiology and Ecology (ICIPE), P.O. Box 30772-00100, Nairobi, Kenya.
International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), P.O. Box 39063-00623, Nairobi, Kenya.
Sci Rep. 2020 Jul 8;10(1):11205. doi: 10.1038/s41598-020-68075-2.
Tritrophic interactions allow plants to recruit natural enemies for protection against herbivory. Here we investigated genetic variability in induced responses to stemborer egg-laying in maize Zea mays (L.) (Poaceae). We conducted a genome wide association study (GWAS) of 146 maize genotypes comprising of landraces, inbred lines and commercial hybrids. Plants were phenotyped in bioassays measuring parasitic wasp Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) attraction to volatiles collected from plants exposed to stemborer Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) eggs. Genotyping-by-sequencing was used to generate maize germplasm SNP data for GWAS. The egg-induced parasitoid attraction trait was more common in landraces than in improved inbred lines and hybrids. GWAS identified 101 marker-trait associations (MTAs), some of which were adjacent to genes involved in the JA-defence pathway (opr7, aos1, 2, 3), terpene biosynthesis (fps3, tps2, 3, 4, 5, 7, 9, 10), benzoxazinone synthesis (bx7, 9) and known resistance genes (e.g. maize insect resistance 1, mir1). Intriguingly, there was also association with a transmembrane protein kinase that may function as a receptor for the egg elicitor and other genes implicated in early plant defence signalling. We report maize genomic regions associated with indirect defence and provide a valuable resource for future studies of tritrophic interactions in maize. The markers identified may facilitate selection of indirect defence by maize breeders.
三营养层相互作用使植物能够招募天敌来保护自己免受食草动物的侵害。在这里，我们研究了玉米（Zea mays）（禾本科）对螟虫产卵诱导反应的遗传变异。我们对包括地方品种、自交系和商业杂交种在内的 146 个玉米基因型进行了全基因组关联研究（GWAS）。在生物测定中，我们对植物进行表型分析，这些生物测定测量了寄生蜂 Cotesia sesamiae（Cameron）（膜翅目：Braconidae）对暴露于螟虫卵的植物挥发物的吸引力。通过测序进行基因分型（GBS），生成用于 GWAS 的玉米种质 SNP 数据。与改良自交系和杂交种相比，地方品种中更容易出现螟虫产卵诱导的寄生蜂吸引特性。GWAS 确定了 101 个标记-性状关联（MTA），其中一些与参与 JA 防御途径（opr7、aos1、2、3）、萜烯生物合成（fps3、tps2、3、4、5、7、9、10）、苯并恶嗪酮合成（bx7、9）和已知抗性基因（如玉米昆虫抗性 1、mir1）的基因相邻。有趣的是，与一种跨膜蛋白激酶也存在关联，该激酶可能作为卵激发子的受体和其他参与早期植物防御信号转导的基因。我们报告了与间接防御相关的玉米基因组区域，并为未来玉米三营养层相互作用的研究提供了有价值的资源。鉴定出的标记可能有助于玉米育种者选择间接防御。
