背景:葡萄(Vitis)是世界上最有价值的水果作物之一,但是食草动物会降低产量。了解昆虫的食草抗性对于减轻这些损失至关重要。Vitislabrusca,一种北美野生葡萄品种,已被用于育种计划,以产生具有增强的非生物和生物胁迫抗性的杂种葡萄,使其成为可持续葡萄栽培的宝贵遗传资源。本研究评估了V.labruscaacc的抗性。\'GREM4\'和葡萄cv。\'PN40024\'葡萄对Popilliajaponica(日本甲虫)食草,并鉴定了这种推定抗性的形态和遗传适应。
结果:\'GREM4\'与\'PN40024\'相比,在30分钟至19小时的选择和非选择草食性试验中,对甲虫草食性具有更大的抵抗力。当甲虫以毛状体密度没有差异的每种物种的叶子为食时,与“PN40024”(9.80mm2)相比,“GREM4”(3.29mm2)中的叶面积明显减少,表明毛状体以外的其他因素有助于\'GREM4\'中的昆虫食草抗性。比较转录组学分析显示,“GREM4”与“PN40024”相比,防御反应和次级代谢产物生物合成基因的组成型(0h)表达更高,表明了增强的构成防御。在食草动物身上,与“PN40024”(502)相比,“GREM4”显示出更多的差异表达基因(690),提出更广泛的回应。在“GREM4”中上调的基因在萜烯生物合成中富集,类黄酮生物合成,植物激素信号,和疾病防御相关的功能,可能有助于增强昆虫的食草动物防御,而在草食性下在“PN40024”中差异表达的基因富含木葡聚糖,细胞壁形成,和钙离子结合。与昆虫草食性防御有关的大多数基因是直系同源物,在\'GREM4\'和\'PN40024\'中具有特定的表达模式,但是一些旁系同源和基因组特异性基因也可能有助于赋予抗性。
结论:我们的研究结果表明,\'GREM4\'昆虫食草抗性归因于多种因素,包括毛状体和与萜烯有关的基因的独特组成型和诱导型表达,类黄酮,和苯丙素生物合成,以及病原体防御。
BACKGROUND: Grapevine (Vitis) is one of the world\'s most valuable fruit crops, but insect herbivory can decrease yields. Understanding insect herbivory resistance is critical to mitigating these losses. Vitis labrusca, a wild North American grapevine species, has been leveraged in breeding programs to generate hybrid grapevines with enhanced abiotic and biotic stress resistance, rendering it a valuable genetic resource for sustainable viticulture. This study assessed the resistance of V. labrusca acc. \'GREM4\' and Vitis vinifera cv. \'PN40024\' grapevines to Popillia japonica (Japanese beetle) herbivory and identified morphological and genetic adaptations underlying this putative resistance.
RESULTS: \'GREM4\' displayed greater resistance to beetle herbivory compared to \'PN40024\' in both choice and no-choice herbivory assays spanning periods of 30 min to 19 h. \'GREM4\' had significantly higher average leaf trichome densities than \'PN40024\' and beetles preferred to feed on the side of leaves with fewer trichomes. When leaves from each species that specifically did not differ in trichome densities were fed on by beetles, significantly less leaf area was damaged in \'GREM4\' (3.29mm2) compared to \'PN40024\' (9.80mm2), suggesting additional factors beyond trichomes contributed to insect herbivory resistance in \'GREM4\'. Comparative transcriptomic analyses revealed \'GREM4\' exhibited greater constitutive (0 h) expression of defense response and secondary metabolite biosynthesis genes compared to \'PN40024\', indicative of heightened constitutive defenses. Upon herbivory, \'GREM4\' displayed a greater number of differentially expressed genes (690) compared to \'PN40024\' (502), suggesting a broader response. Genes up-regulated in \'GREM4\' were enriched in terpene biosynthesis, flavonoid biosynthesis, phytohormone signaling, and disease defense-related functions, likely contributing to heighted insect herbivory defense, while genes differentially expressed in \'PN40024\' under herbivory were enriched in xyloglucan, cell wall formation, and calcium ion binding. The majority of genes implicated in insect herbivory defense were orthologs with specific expression patterns in \'GREM4\' and \'PN40024\', but some paralogous and genome-specific genes also likely contributed to conferring resistance.
CONCLUSIONS: Our findings suggest that \'GREM4\' insect herbivory resistance was attributed to a combination of factors, including trichomes and unique constitutive and inducible expression of genes implicated in terpene, flavonoid, and phenylpropanoid biosynthesis, as well as pathogen defense.