Cao Wenguang, Cao Biting, Wang Xuan, Bai Jinjuan, Xu Yong-Zhen, Zhao Jianjun, Li Xiaorong, He Yuke, Hu Shengwu
National Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Shanghai Institutes of Plant Physiology & Ecology, Chinese Academy of Science, 300 Fenglin Road, Shanghai, 200032 China.
State Key Laboratory of Crop Stress Biology in Arid Areas and College of Agronomy, Northwest A&F University, Yangling, Shaanxi China.
Hortic Res. 2020 Oct 1;7(1):160. doi: 10.1038/s41438-020-00378-x. eCollection 2020.
The curd of cauliflower ( L. var. ) is a modified inflorescence that is consumed as a vegetable. Curd formation is proposed to be due to a mutation in the () gene, but the genetic relationship between variation and curd morphotypes remains obscure. To address this question, we collected and classified a collection of 78 cauliflower accessions into four subpopulations according to curd surface features: smooth, coarse, granular, and hairy curd morphotypes. Through the cDNA sequencing of alleles, we showed that smooth and coarse accessions characterized by inflorescence meristem arrest presented a strong association with the 451T SNP (), whereas granular and hairy accessions marked with floral organ arrest presented an association with 451G (). Interestingly, all alleles were alternatively spliced, resulting in a total of four alternative splice (AS) variants due to the retention of the fourth and/or seventh introns. Among accessions with alleles, the total expression of all these AS variants in granular plants was almost equal to that in hairy plants; however, the expression of the individual AS variants encoding intact proteins relative to those encoding truncated proteins differed. Hairy accessions showed relatively high expression of the individual variants encoding intact proteins, whereas granular accessions displayed relatively low expression. In smooth cauliflower, the overexpression of the variant caused an alteration in the curd morphotype from smooth to hairy, concurrent with an increase in the expression levels of downstream floral identity genes. These results reveal that alternative splicing of transcripts is involved in the determination of cauliflower curd morphotypes.
花椰菜（L. var.）的花球是一种经过改良的花序，可作为蔬菜食用。花球的形成被认为是由于（）基因发生突变，但（）变异与花球形态类型之间的遗传关系仍不清楚。为了解决这个问题，我们根据花球表面特征将78份花椰菜种质收集并分类为四个亚群：光滑、粗糙、颗粒状和多毛花球形态类型。通过对等位基因的cDNA测序，我们发现以花序分生组织停滞为特征的光滑和粗糙种质与451T SNP（）有很强的关联，而以花器官停滞为特征的颗粒状和多毛种质与451G（）有关联。有趣的是，所有等位基因都发生了可变剪接，由于第四和/或第七内含子的保留，总共产生了四种可变剪接（AS）变体。在具有等位基因的种质中，颗粒状植株中所有这些AS变体的总表达量几乎与多毛植株中的相等；然而，编码完整蛋白质的单个AS变体相对于编码截短蛋白质的变体的表达有所不同。多毛种质中编码完整蛋白质的单个变体表达相对较高，而颗粒状种质中表达相对较低。在光滑型花椰菜中，该变体的过表达导致花球形态从光滑变为多毛，同时下游花器官特征基因的表达水平增加。这些结果表明，转录本的可变剪接参与了花椰菜花球形态类型的决定。
