林萍 王明元 李雨晴 刘建福, 张华英 林思锻

摘  要：尖孢镰刀菌（Fusarium oxysporum f. sp. Cubense， Foc）引起的香蕉枯萎病是我国香蕉的主要病害之一，严重影响香蕉的产量和品质。TGA防御反应基因在香蕉应对尖孢镰刀菌胁迫的应答转录调控过程中至关重要。本研究以拟南芥TGA转录因子家族成员蛋白为查询序列，在香蕉基因组数据库中Blast筛选出TGA转录因子家族成员，并对该家族成员进行生物信息学分析。共鉴定得到9个香蕉TGA家族成员，分别命名为MaTGA1～MaTGA9;香蕉TGA家族蛋白富含酸性氨基酸，大部分蛋白以α螺旋为主;亚细胞定位主要在细胞核内。进化树分析表明，香蕉MaTGA转录因子家族的9个成员可分为Class Ⅰ和Class Ⅱ两类，基因结构及功能结构域的分布情况也呈现出高度一致。进一步通过RT-qPCR分析发现，MaTGA2、MaTGA3和MaTGA8在香蕉枯萎病菌侵染后的‘威廉斯（易感病）及‘南天黄（抗病）中均显著下调表达，MaTGA1、MaTGA6、MaTGA7和MaTGA9均呈现先下降后上升的趋势;然而MaTGA4和MaTGA5仅在‘威廉斯中上调表达，以上结果表明MaTGA2、MaTGA3和MaTGA8在香蕉抗枯萎病中发挥重要的生物学功能。本研究结果为香蕉TGA转录因子功能挖掘奠定理论基础。

关键词：香蕉;TGA转录因子;生物信息学分析;基因表达分析

Abstract： Banana fusarium wilt， caused by Fusarium oxysporum f. sp. Cubense （Foc）， is one of the major diseases in banana-producing areas in China， seriously affects the yield and quality of bananas. The transcription and its regulation of the TGA defense response gene is a crucial role in banana responses to the challenge of Fusarium oxysporum stress. In this study， using the TGA transcription factor family members protein sequences from Arabidopsis as the query， the banana TGA transcription factor family members were blasted in the banana genome database and analyzed using bioinformatics analysis. A total of 9 family members were identified， named as MaTGA1～ MaTGA9. TGA family proteins of banana was rich in acidic amino acids， and most of the proteins were alpha helices. The subcellular location was mainly in the nucleus. The nine MaTGA transcription factor members could be classified into two groups， Class Ⅰ and Class Ⅱ， by phylogenetic tree analysis. The distribution of gene structure and functional domains also showed a high degree of consistency. The RT-qPCR analysis showed that MaTGA2， MaTGA3， and MaTGA8 were significantly down-regulated both in Williams （susceptible） and Nantianhuang （disease-resistant） after Foc infection， and the gene espression of MaTGA1， MaTGA6， MaTGA7 and MaTGA9 declined first and then rose， however MaTGA4 and MaTGA5 were only up-regulated in William， indicating that MaTGA2， MaTGA3， and MaTGA8 played important biological functions in banana resistance to wilt. The results of this study would lay a theoretical foundation for the function excavation of banana TGA transcription factors.

Keywords： banana （Musa spp.）; TGA transcription factor; gioinformatic analysis; gene expression analysis

香蕉（Musa spp.）與柑橘、葡萄、苹果共同被联合国粮农组织列为世界四大水果。但近年来，香蕉枯萎病在世界大部分的种植区域爆发，导致香蕉种植面积急剧减少，香蕉市场受到严重打击[1-2]，因此探究香蕉枯萎病防御反应的分子机理对于枯萎病的防治意义重大。

TGA转录因子是bZIP（basic leucine zipper，bZIP）家族的D亚族[3]，能够特异性识别并结合TGACG为核心的激活序列（activation sequence， as-1），调节下游靶标基因的表达，在调节植株抗性及花器官发育中发挥着重要作用[4]。……