Leaf trichomes protect against various biotic and abiotic stresses in plants. However, there is little knowledge about this trait in oilseed rape (Brassica napus). Here, we demonstrated that hairy leaves were less attractive to Plutella xylostella larvae than glabrous leaves. We established a core germplasm collection with 290 accessions for a genome-wide association study (GWAS) of the leaf trichome trait in oilseed rape. We compared the transcriptomes of the shoot apical meristem (SAM) between hairy- and glabrous-leaf genotypes to narrow down the candidate genes identified by GWAS. The single nucleotide polymorphisms and the different transcript levels of BnaA.GL1.a, BnaC.SWEET4.a, BnaC.WAT1.a and BnaC.WAT1.b corresponded to the divergence of the hairy- and glabrous-leaf phenotypes, indicating the role of sugar and/or auxin signalling in leaf trichome initiation. The hairy-leaf SAMs had lower glucose and sucrose contents but higher expression of putative auxin responsive factors than the glabrous-leaf SAMs. Spraying of exogenous auxin (8 μm) increased leaf trichome number in certain genotypes, whereas spraying of sucrose (1%) plus glucose (6%) slightly repressed leaf trichome initiation. These data contribute to the existing knowledge about the genetic control of leaf trichomes and would assist breeding towards the desired leaf surface type in oilseed rape.

中文翻译：

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全基因组关联研究揭示了多倍体油菜（Brassica napus L.）中与叶片毛状体形成有关的新基因。

叶片毛状体可抵御植物中各种生物和非生物胁迫。但是，对油菜（甘蓝型油菜）的这一特性知之甚少。在这里，我们证明了毛状叶片对小菜蛾幼虫的吸引力小于无毛叶片。我们建立了290个种质的核心种质资源库，用于油菜油菜叶片毛状体性状的全基因组关联研究（GWAS）。我们比较了毛状和毛状叶基因型之间的茎尖分生组织（SAM）的转录组，以缩小由GWAS鉴定的候选基因。BnaA.GL1.a，BnaC.SWEET4.a，BnaC.WAT1.a和BnaC.WAT1.b的单核苷酸多态性和不同的转录水平对应于毛状和毛状叶表型的差异，表明糖和/或生长素信号传导在叶片毛状体起始中的作用。与无毛叶SAMs相比，有毛叶SAMs的葡萄糖和蔗糖含量较低，但生长素应答因子的表达较高。喷洒外源生长素（8μm）在某些基因型中增加了叶片毛状体的数量，而喷洒蔗糖（1％）加葡萄糖（6％）则稍微抑制了叶片毛状体的起始。这些数据有助于有关叶毛的遗传控制的现有知识，并有助于朝油菜中所需的叶表面类型进行育种。喷洒蔗糖（1％）加葡萄糖（6％）会稍微抑制叶片毛状体的萌生。这些数据有助于有关叶毛的遗传控制的现有知识，并有助于朝油菜中所需的叶表面类型进行育种。喷洒蔗糖（1％）加葡萄糖（6％）会稍微抑制叶片毛状体的萌生。这些数据有助于有关叶毛的遗传控制的现有知识，并有助于朝油菜中所需的叶表面类型进行育种。