National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.
Hubei Key Laboratory of Agricultural Bioinformatics, College of Informatics, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
Theor Appl Genet. 2018 Dec;131(12):2699-2708. doi: 10.1007/s00122-018-3184-5. Epub 2018 Sep 15.
BnA10.LMI1 positively regulates the development of leaf lobes in Brassica napus, and cis-regulatory divergences cause the different allele effects. Leaf shape is an important agronomic trait, and large variations in this trait exist within the Brassica germplasm. The lobed leaf is a unique morphological characteristic for Brassica improvement. Nevertheless, the molecular basis of leaf lobing in Brassica is poorly understood. Here, we show that an incompletely dominant locus, BnLLA10, is responsible for the lobed-leaf shape in rapeseed. A LATE MERISTEM IDENTITY1 (LMI1)-like gene (BnA10.LMI1) encoding an HD-Zip I transcription factor is the causal gene underlying the BnLLA10 locus. Sequence analysis of parental alleles revealed no sequence variations in the coding sequences, whereas abundant variations were identified in the regulatory region. Consistent with this finding, the expression levels of BnLMI1 were substantially elevated in the lobed-leaf parent compared with its near-isogenic line. The knockout mutations of BnA10.LMI1 gene were induced using the CRISPR/Cas9 system in both HY (the lobed-leaf parent) and J9707 (serrated leaf) genetic backgrounds. BnA10.LMI1 null mutations in the HY background were sufficient to produce unlobed leaves, whereas null mutations in the J9707 background showed no obvious changes in leaf shape compared with the control. Collectively, our results indicate that BnA10.LMI1 positively regulates the development of leaf lobes in B. napus, with cis-regulatory divergences causing the different allelic effects, providing new insights into the molecular mechanism of leaf lobe formation in Brassica crops.
BnA10.LMI1 正向调控油菜叶片裂片的发育，顺式调控分歧导致不同等位基因的效应。叶片形状是一个重要的农艺性状，在芸薹属种质资源中存在着很大的变异。裂片叶是芸薹属改良的一个独特的形态特征。然而，芸薹属叶片裂片形成的分子基础知之甚少。在这里，我们表明一个不完全显性位点 BnLLA10 负责油菜的裂片叶形状。一个晚期分生组织 IDENTITY1（LMI1）样基因（BnA10.LMI1）编码一个 HD-Zip I 转录因子，是 BnLLA10 位点的候选基因。亲本等位基因的序列分析表明，编码序列没有序列变异，而在调控区则存在丰富的变异。与这一发现一致的是，BnLMI1 的表达水平在裂片叶亲本中明显高于其近等基因系。利用 CRISPR/Cas9 系统在 HY（裂片叶亲本）和 J9707（锯齿叶）遗传背景下诱导 BnA10.LMI1 基因的敲除突变。在 HY 背景下，BnA10.LMI1 基因的 null 突变足以产生无裂片的叶片，而在 J9707 背景下的 null 突变与对照相比，叶片形状没有明显变化。综上所述，我们的结果表明，BnA10.LMI1 正向调控油菜叶片裂片的发育，顺式调控分歧导致不同等位基因的效应，为芸薹属作物叶片裂片形成的分子机制提供了新的见解。
