日本落叶松 ABCG 基因家族鉴定及其抗旱功能初探

Identification of ABCG gene family in Larix kaempferi and preliminary exploration on its drought resistance function

摘要

【目的】日本落叶松是我国北方重要的速生用材树种，干旱胁迫显著影响其生长发育和人工林生产力，而 ABCG 转运蛋白在植物物质转运、表皮屏障形成及逆境响应中具有重要作用。系统鉴定并分析日本落叶松 ATP 结合盒转运蛋白 G 亚家族（ ABCG）基因，并评估其在干旱胁迫响应中的潜在作用。【方法】采用生物信息学方法对日本落叶松 ABCG 基因家族进行全基因组鉴定，并开展系统发育、保守基序、启动子顺式作用元件及分子对接分析；结合实时荧光定量 PCR 检测其在不同组织及干旱处理下的表达模式，并通过酵母异源表达体系对候选基因进行初步功能验证。【结果】（1）共鉴定获得 20 个 LkABCG 基因，分布于 13 条 scaffold 上。（2）系统发育分析表明，日本落叶松 ABCG 家族成员分布于 3 个主要类群，且 Group Ic 中未检测到成员；保守基序与 Ka/Ks 分析表明，该家族整体保守，但亚组间存在一定分化。（3）分子对接结果显示，不同 LkABCG 蛋白与植物激素、苯丙烷相关代谢物及脂质/表皮屏障相关化合物的预测亲和力存在差异。（4）启动子区存在多类激素响应与逆境响应相关顺式作用元件；表达分析显示， LkABCG 基因在各组织中呈现不同的表达模式，部分成员在干旱胁迫下响应不同。（5）在 6% PEG4000 模拟干旱胁迫下，表达 LkABCG36 的酵母较对照生长更好，提示其可能参与干旱胁迫响应。【结论】日本落叶松 LkABCG 基因家族在进化上总体较为保守，但不同类群成员可能存在功能分化；综合结构进化特征、调控元件组成、表达响应、分子对接及酵母异源表达结果表明，部分 LkABCG 基因可能参与干旱胁迫响应过程，为抗旱相关候选基因筛选与后续功能验证提供依据。

Abstract

[Objective] Larix kaempferi is an important fast-growing timber species in northern China. Drought stress markedly affects its growth, development and plantation productivity, while ATP-binding cassette subfamily G (ABCG) transporters play important roles in substrate transport, epidermal barrier formation and stress responses in plants. This paper systematically identifies and characterizes the ATP-binding cassette G subfamily (ABCG) genes in Larix kaempferi and evaluates their potential roles in drought stress response. [Method] A genome-wide survey of ABCG gene family in L. kaempferi was conducted using bioinformatics approaches, followed by analyses of phylogenetic relationships, conserved motifs, promoter cis-acting elements, and molecular docking. In addition, the expression patterns of these genes in different tissues under drought treatment were examined by real-time quantitative PCR, and a candidate gene was preliminarily evaluated using a yeast heterologous expression system. [Result] (1) A total of 20 LkABCG genes were identified and distributed across 13 scaffolds. (2) Phylogenetic analysis classified the LkABCG family into three major groups, with no members assigned to Group Ic. Combined analyses of conserved motifs and Ka/Ks values indicated that the family was generally evolutionarily conserved, although divergence among subgroups was evident. (3) Molecular docking suggested that different LkABCG proteins may have distinct binding preferences for phytohormones, phenylpropanoid-related metabolites, and lipid- or cuticular barrier-related compounds. (4) Numerous hormone- and stress-responsive cis-acting elements were identified in promoter regions of LkABCG genes. Expression analysis revealed differential expression among tissues, and several genes responded markedly to drought treatment. (5) Under 6% PEG4000-simulated drought stress, yeast expressing LkABCG36 showed better growth than control, suggesting that it may be involved in drought stress response. [Conclusion] The LkABCG gene family is generally conserved in L. kaempferi, whereas functional diversification may have occurred among different groups. Evidence from sequence features, promoter composition, expression profiles, docking predictions, and yeast assays suggests that some LkABCG genes may participate in drought-related stress responses. These findings provide a basis for identifying drought-responsive candidate genes and for further functional validation in L. kaempferi.

关键词

日本落叶松 / ABCG 基因家族 / 干旱胁迫 / 表达分析 / 分子对接

Key words

Larix kaempferi / ABCG gene family / drought stress / expression analysis / molecular docking

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基金资助

农业生物育种重大专项(2023ZD04058)