The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Advanced Agricultural Sciences, Zhejiang A&F University, Linan, Hangzhou, 311300, Zhejiang, China.
College of Advanced Agricultural Sciences, Zhejiang A&F University, Linan, Hangzhou, 311300, Zhejiang, China.
Mol Biol Rep. 2024 Apr 5;51(1):479. doi: 10.1007/s11033-024-09412-w.
GLABRA3 (GL3) and ENHANCER OF GLABRA3 (EGL3) genes encode a typical helix-loop-helix (bHLH) transcription factors that primarily regulate trichome branching and root hair development, DNA endoreduplication, trichoblast size, and stomatal formation. The functions of GL3 genes in cotton crop have been poorly characterized. In this study, we performed comprehensive genome-wide scans for GL3 and EGL3 homologs to enhance our comprehension of their potential roles in trichome and fiber development in cotton crop.
Our findings paraded that Gossypium hirsutum and G. barbadense have 6 GL3s each, unevenly distributed on 4 chromosomes whereas, G. arboreum, and G. raimondii have 3 GL3s each, unevenly distributed on 2 chromosomes. Gh_A08G2088 and Gb_A09G2187, despite having the same bHLH domain as the other GL3 genes, were excluded due to remarkable short sequences and limited number of motifs, indicating a lack of potential functional activity. The phylogenetic analysis categorized remaining 16 GL3s into three subfamilies (Group I-III) closely related to A. thaliana. The 16 GL3s have complete bHLH domain, encompassing 590-631 amino acids, with molecular weights (MWs) ranging from 65.92 to 71.36 kDa. Within each subfamily GL3s depicted shared similar gene structures and motifs, indicating conserved characteristics within respective groups. Promoter region analysis revealed 27 cis-acting elements, these elements were responsive to salicylic acid, abscisic acid (ABA), methyl jasmonate (MeJA), and gibberellin. The expression of GL3 genes was analyzed across 12 tissues in both G. barbadense and G. hirsutum using the publicly available RNA-seq data. Among GL3s, Gb_D11G0219, Gb_D11G0214, and Gb_D08G2182, were identified as relatively highly expressed across different tissues, consequently selected for hormone treatment and expression validation in G. barbadense. RT-qPCR results demonstrated significant alterations in the expression levels of Gb_D11G0219 and Gb_D11G0214 following MeJA, GA, and ABA treatment. Subcellular localization prediction revealed that most GL3 proteins were predominantly expressed in the nucleus, while a few were localized in the cytoplasm and chloroplasts.
In summary, this study lays the foundation for subsequent functional validation of GL3 genes by identifying hormonal regulation patterns and probable sites of action in cotton trichome formation and fiber development. The results stipulate a rationale to elucidate the roles and regulatory mechanisms of GL3 genes in the intricate process of cotton fibre and trichome development.
GLABRA3（GL3）和 ENHANCER OF GLABRA3（EGL3）基因编码典型的螺旋-环-螺旋（bHLH）转录因子，主要调控毛状体分支和根毛发育、DNA 内复制、毛原细胞大小和气孔形成。GL3 基因在棉花作物中的功能尚未得到充分描述。在这项研究中，我们进行了全基因组范围内的 GL3 和 EGL3 同源物扫描，以增强我们对它们在棉花作物毛状体和纤维发育中潜在作用的理解。
我们的研究结果表明，陆地棉和亚洲棉各有 6 个 GL3，不均匀分布在 4 条染色体上，而非洲棉和雷蒙德氏棉各有 3 个 GL3，不均匀分布在 2 条染色体上。Gh_A08G2088 和 Gb_A09G2187 尽管与其他 GL3 基因具有相同的 bHLH 结构域，但由于序列显著较短且基序数量有限，被排除在外，表明其缺乏潜在的功能活性。剩余的 16 个 GL3 经过系统发育分析被归类为与拟南芥密切相关的三个亚家族（I-III 组）。这 16 个 GL3 都具有完整的 bHLH 结构域，包含 590-631 个氨基酸，分子量（MW）在 65.92 到 71.36 kDa 之间。在每个亚家族中，GL3 都具有相似的基因结构和基序，表明在各自的组内具有保守的特征。启动子区域分析显示有 27 个顺式作用元件，这些元件对水杨酸、脱落酸（ABA）、茉莉酸甲酯（MeJA）和赤霉素有反应。使用公共可用的 RNA-seq 数据，在亚洲棉和陆地棉的 12 种组织中分析了 GL3 基因的表达。在 GL3 中，Gb_D11G0219、Gb_D11G0214 和 Gb_D08G2182 在不同组织中被鉴定为相对高表达，因此被选为激素处理和在亚洲棉中表达验证的候选基因。RT-qPCR 结果表明，Gb_D11G0219 和 Gb_D11G0214 的表达水平在 MeJA、GA 和 ABA 处理后发生显著变化。亚细胞定位预测表明，大多数 GL3 蛋白主要在细胞核中表达，而少数在细胞质和叶绿体中表达。
总之，本研究通过鉴定棉花毛状体形成和纤维发育过程中的激素调控模式和可能的作用部位，为 GL3 基因的后续功能验证奠定了基础。研究结果为阐明 GL3 基因在棉花纤维和毛状体发育这一复杂过程中的作用和调控机制提供了依据。
Zotero 插件