College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
Int J Mol Sci. 2022 Nov 3;23(21):13454. doi: 10.3390/ijms232113454.
Wax is an acellular structural substance attached to the surface of plant tissues. It forms a protective barrier on the epidermis of plants and plays an important role in resisting abiotic and biotic stresses. In this paper, nonheading Chinese cabbage varieties with and without wax powder were observed using scanning electron microscopy, and the surface of waxy plants was covered with a layer of densely arranged waxy crystals, thus differentiating them from the surface of waxless plants. A genetic analysis showed that wax powder formation in nonheading Chinese cabbage was controlled by a pair of dominant genes. A preliminary bulked segregant analysis sequencing (BSA-seq) assay showed that one gene was located at the end of chromosome A09. Within this interval, we identified BraA09000626, encoding an AP2 transcription factor homologous to Arabidopsis AtSHINE3, and we named it BrSHINE3. By comparing the CDS of the gene in the two parental plants, a 35 bp deletion in the BrSHINE3 gene of waxless plants resulted in a frameshift mutation. Tissue analysis showed that BrSHINE3 was expressed at significantly higher levels in waxy plant rosette stage petioles and bolting stage stems than in the tissues of waxless plants. We speculate that this deletion in BrSHINE3 bases in the waxless material may inhibit wax synthesis. The overexpression of BrSHINE3 in Arabidopsis induced the accumulation of wax on the stem surface, indicating that BrSHINE3 is a key gene that regulates the formation of wax powder in nonheading Chinese cabbage. The analysis of the subcellular localization showed that BrSHINE3 is mainly located in the nucleus and chloroplast of tobacco leaves, suggesting that the gene may function as a transcription factor. Subsequent transcriptome analysis of the homology of BrSHINE3 downstream genes in nonheading Chinese cabbage showed that these genes were downregulated in waxless materials. These findings provide a basis for a better understanding of the nonheading Chinese cabbage epidermal wax synthesis pathway and provide important information for the molecular-assisted breeding of nonheading Chinese cabbage.
蜂蜡是一种附着在植物组织表面的无细胞结构物质。它在植物表皮上形成一层保护性屏障，在抵抗非生物和生物胁迫方面发挥着重要作用。在本文中，我们使用扫描电子显微镜观察了有蜡粉和无蜡粉的不结球白菜品种，结果表明，有蜡粉的植株表面覆盖着一层排列紧密的蜡质晶体，这与无蜡粉的植株表面有所区别。遗传分析表明，不结球白菜的蜡粉形成受一对显性基因控制。初步的 bulked segregant analysis sequencing (BSA-seq) 分析表明，一个基因位于染色体 A09 的末端。在这个区间内，我们鉴定到 BraA09000626，它编码一个与拟南芥 AtSHINE3 同源的 AP2 转录因子，我们将其命名为 BrSHINE3。通过比较两个亲本植物基因的 CDS，我们发现无蜡粉植株中 BrSHINE3 基因的 35bp 缺失导致移码突变。组织分析表明，BrSHINE3 在有蜡粉植株的莲座期叶柄和抽薹期茎中表达水平显著高于无蜡粉植株的组织。我们推测，无蜡粉材料中 BrSHINE3 基因的这种缺失可能抑制了蜡的合成。在拟南芥中过表达 BrSHINE3 诱导茎表面蜡的积累，表明 BrSHINE3 是调控不结球白菜蜡粉形成的关键基因。亚细胞定位分析表明，BrSHINE3 主要定位于烟草叶片的细胞核和叶绿体中，提示该基因可能作为转录因子发挥作用。随后对不结球白菜 BrSHINE3 下游同源基因的转录组分析表明，这些基因在无蜡粉材料中下调。这些发现为更好地理解不结球白菜表皮蜡合成途径提供了依据，为不结球白菜的分子辅助育种提供了重要信息。
