张郎织 李季肤 黄杰 王志勇 陈志坚

摘  要：铝毒被认为是酸性土壤上抑制植物根系生长的重要胁迫因素之一。多药及毒性化合物外排转运蛋白（multidrug and toxic compound extrusion，MATE）在根系柠檬酸转运耐铝毒中起重要作用。以地毯草（Axonopus compressus）为材料，对AcMATE1基因进行克隆、生物信息学和基因表达分析。结果表明：铝处理抑制了地毯草根系的生长，包括总根长、根表面积和根体积。通过PCR克隆到地毯草AcMATE1基因，该基因cDNA全长1602 bp，编码433个氨基酸残基。AcMATE1蛋白分子量为45.9 kDa，属于疏水性蛋白。AcMATE1蛋白包含MatE保守结构域和9个跨膜结构域。亚细胞定位预测分析结果表明，AcMATE1定位于细胞膜上。实时荧光定量PCR结果表明，金属铝（Al）和镉（Cd）处理显著增强AcMATE1基因在地毯草根系中的表达，而镧（La）处理则抑制AcMATE1基因的表达。并且不同铝浓度和时间处理进一步验证Al可增强AcMATE1基因在地毯草根中的表达。此外，AcMATE1基因在地毯草根、茎和叶中均有表达，且在0～1 cm根段中的表达量高于其他根段中的表达量。本研究结果为解析地毯草响应铝毒害的机理提供候选基因资源。

关键词：地毯草;铝毒;MATE转运蛋白;根系;基因表达

中图分类号：Q945.78      文獻标识码：A

Cloning and Expression Analysis of AcMATE1 in Axonopus compressus

ZHANG Langzhi1， LI Jifu1， HUANG Jie1， WANG Zhiyong1*， CHEN Zhijian1，2*

1. College of Forestry， Hainan University / Key Laboratory of Genetics and Germplasm Innovation of Tropical Special Forest Trees and Ornamental Plants， Ministry of Education， Haikou， Hainan 570228， China; 2. Institute of Tropical Crop Genetic Resources， Chinese Academy of Tropical Agriculture Sciences / Key Laboratory of Crop Gene Resources and Germplasm Enhancement in Southern China， Ministry of Agriculture and Rural Affairs， Haikou， Hainan 571101， China

Abstract： Aluminum （Al） toxicity is one of the serious constraints inhibiting root growth in acid soils. The MATE （Multidrug and toxic compound extrusion） transporter plays important roles in citrate exudation for plant Al detoxification. In this study， cloning， bioinformatic and expression analyses of AcMATE1 were performed in carpetgrass （Axonopus compressus）. Results showed the that root growth of carpetgrass was inhibited by Al toxicity， as reflected by the decreases in total root length， root surface area and root volume. The full length of AcMATE1 was 1602 bp， encoding 433 amino acid residues. AcMATE1， with protein molecular weight of 45.9 kDa， was predicted to be a hydrophobic protein. Furthermore， AcMATE1 contained one conserved MatE domain and nine transmembrane domains. AcMATE1 was found to be localized on the plasma membrane based on subcellular localization prediction. Quantitative real time PCR analysis showed that the expressions of AcMATE1 were enhanced in the roots of carpetgrass under both Al and Cd treatments， whereas the expression of AcMATE1 was inhibited by La treatment. The transcription level of AcMATE1 increased in the roots of carpetgrass by Al treatments of different concentration and duration. Moreover， the transcripts of AcMATE1 could be detected in roots， stems and leaves， and AcMATE1 exhibited the highest expression in the root tip with 0 to 1 cm in length. This study would provide candidate gene resources for the further dissection of carpetgrass adaptation to Al toxicity.

Keywords： Axonopus compressus; aluminum toxicity; MATE transporter; root; gene expression

DOI： 10.3969/j.issn.1000-2561.2021.07.007

铝（aluminum，Al）是地壳中分布最广泛的金属元素和第3大常见的元素[1]。当土壤pH低于5.0时，铝离子（Al3+）就会从土壤硅酸盐或氧化物中释放出来溶解到土壤溶液中，对植物造成毒害[2]。因此，铝毒被认为是酸性土壤上限制作物生长的主要因素之一。铝离子主要通过破坏细胞核结构、扰乱膜电势和降低细胞壁延展性等方面损害根尖细胞，进而抑制根系生长[3-4]。……