State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, 712100, China; Shandong Institute of Pomology, Tai'an, 271000, China.
State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, 712100, China.
Plant Physiol Biochem. 2018 Dec;133:81-91. doi: 10.1016/j.plaphy.2018.10.033. Epub 2018 Oct 30.
Tyrosine aminotransferase (TAT, EC 2.6.1.5) is the first key enzyme that catalyzes the reversible interconversion of tyrosine and 4-hydroxyphenylpyruvate in the tyrosine-derived pathway for syntheses of important secondary metabolites and compounds. Although plant TAT genes have been proposed to be important in response to abiotic stress, there is little information about TAT genes in woody perennial tree species, especially in economic fruit trees. Based on TAT domain searching, sequence homology screening and phylogenetic analysis, we identified four TATs in apple genome. Then, we carried out a detailed phylogenetic analysis of TAT genes from multi-species, focusing on apple (Malus domestica). The result showed that the TAT family comprises three major classes corresponding to genes from angiosperms, mammals, and bacteria. Angiosperm TAT genes could be further divided into six subclasses. Analysis of intron-exon structure revealed that the typical TAT gene contains six introns and seven exons, with exons of similar size at each exon location. Promoter analysis showed that the 5'-flanking region of apple MdTATs contain multiple cis-acting elements including those implicated in light, biotic stress, abiotic stress, and hormone response. MdTATs were expressed to various levels in all apple structures and organs evaluated, and showed distinct expression patterns under water deficit stress. Ectopic expression of MdTAT2 in Arabidopsis or over-expression of MdTAT2 in apple callus tissue conferred enhanced tolerance to drought and osmotic stress. Collectively, these results suggest a role for TAT genes in drought and osmotic stresses and provide valuable information for further research of TAT genes and their function in plants.
酪氨酸转氨酶（TAT，EC 2.6.1.5）是催化酪氨酸和 4-羟基苯丙酮酸可逆互变的第一个关键酶，在酪氨酸衍生途径中合成重要的次生代谢物和化合物。虽然植物 TAT 基因被认为在应对非生物胁迫中很重要，但关于木本多年生树种，尤其是经济果树中的 TAT 基因的信息却很少。基于 TAT 结构域搜索、序列同源性筛选和系统发育分析，我们在苹果基因组中鉴定出了 4 个 TAT。然后，我们对来自多物种的 TAT 基因进行了详细的系统发育分析，重点是苹果（Malus domestica）。结果表明，TAT 家族包括三个主要类群，对应于被子植物、哺乳动物和细菌的基因。被子植物 TAT 基因可进一步分为六个亚类。内含子-外显子结构分析表明，典型的 TAT 基因包含六个内含子和七个外显子，每个外显子位置的外显子大小相似。启动子分析表明，苹果 MdTATs 的 5'侧翼区含有多个顺式作用元件，包括与光、生物胁迫、非生物胁迫和激素反应有关的元件。在所有评估的苹果结构和器官中，MdTATs 的表达水平各不相同，并在水分亏缺胁迫下表现出明显的表达模式。在拟南芥中异位表达 MdTAT2 或在苹果愈伤组织中过表达 MdTAT2 赋予其对干旱和渗透胁迫的增强耐受性。总之，这些结果表明 TAT 基因在干旱和渗透胁迫中起作用，并为进一步研究 TAT 基因及其在植物中的功能提供了有价值的信息。
