鉴定与棉花纤维发育过程中油菜素内酯（BR）信号相关的 bHLH/HLH 基因。

Characterization of bHLH/HLH genes that are involved in brassinosteroid (BR) signaling in fiber development of cotton (Gossypium hirsutum).

机构信息

Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, 430079, China.

出版信息

BMC Plant Biol. 2018 Nov 27;18(1):304. doi: 10.1186/s12870-018-1523-y.

BACKGROUND

Basic helix-loop-helix/helix-loop-helix (bHLH/HLH) transcription factors play important roles in plant development. Many reports have suggested that bHLH/HLH proteins participate in brassinosteroid (BR) hormone signaling pathways to promote cell elongation. Cotton fibers are single-cells and derived from seed surface. To explore the roles of bHLH/HLH proteins in cotton fiber development progress by modulating BR signaling pathway, we performed a systematic analysis of the bHLH/HLH gene family in upland cotton (Gossypium hirsutum) genome.

RESULTS

In this study, we identified 437 bHLH/HLH genes in upland cotton (G. hirsutum) genome. Phylogenetic analysis revealed that GhbHLH/HLH proteins were split into twenty six clades in the tree. These GhbHLH/HLH genes are distributed unevenly in different chromosomes of cotton genome. Segmental duplication is the predominant gene duplication event and the major contributor for amplification of GhbHLH/HLH gene family. The GhbHLH/HLHs within the same group have conserved exon/intron pattern and their encoding proteins show conserved motif composition. Based on transcriptome data, we identified 77 GhbHLH/HLH candidates that are expressed at relatively high levels in cotton fibers. As adding exogenous BR (brassinolide, BL) or brassinazole (Brz, a BR biosynthesis inhibitor), expressions of these GhbHLH/HLH genes were up-regulated or down-regulated in cotton fibers. Furthermore, overexpression of GhbHLH282 (one of the BR-response genes) in Arabidopsis not only promoted the plant growth, but also changed plant response to BR signaling.

CONCLUSION

Collectively, these data suggested that these GhbHLH/HLH genes may participate in BR signaling transduction during cotton fiber development. Thus, our results may provide a valuable reference data as the basis for further studying the roles of these bHLH/HLH genes in cotton fiber development.

背景

碱性螺旋-环-螺旋/螺旋-环-螺旋（bHLH/HLH）转录因子在植物发育中发挥重要作用。许多报道表明，bHLH/HLH 蛋白参与油菜素内酯（BR）激素信号通路，以促进细胞伸长。棉纤维是单细胞，来源于种子表面。为了通过调节 BR 信号通路来探索 bHLH/HLH 蛋白在棉花纤维发育过程中的作用，我们对陆地棉（Gossypium hirsutum）基因组中的 bHLH/HLH 基因家族进行了系统分析。

结果

在这项研究中，我们在陆地棉（G. hirsutum）基因组中鉴定了 437 个 bHLH/HLH 基因。系统发育分析表明，Gh bHLH/HLH 蛋白在树中分为 26 个分支。这些 Gh bHLH/HLH 基因在棉花基因组的不同染色体上不均匀分布。片段复制是主要的基因复制事件，是 Gh bHLH/HLH 基因家族扩增的主要原因。同一组内的 Gh bHLH/HLH 具有保守的外显子/内含子模式，其编码蛋白具有保守的基序组成。基于转录组数据，我们鉴定了 77 个在棉花纤维中表达水平较高的 Gh bHLH/HLH 候选基因。添加外源 BR（油菜素内酯，BL）或油菜素唑（Brz，BR 生物合成抑制剂）后，这些 Gh bHLH/HLH 基因在棉花纤维中的表达上调或下调。此外，在拟南芥中过表达 Gh bHLH282（BR 响应基因之一）不仅促进了植物的生长，还改变了植物对 BR 信号的响应。