Cao Boning, Long Dingpei, Zhang Meng, Liu Changying, Xiang Zhonghuai, Zhao Aichun
State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China.
State Key Laboratory of Silkworm Genome Biology, Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing 400716, China.
Plant Physiol Biochem. 2016 Feb;99:49-58. doi: 10.1016/j.plaphy.2015.12.010. Epub 2015 Dec 20.
Na(+)/H(+) exchangers (NHXs) have important roles in cellular pH, and Na(+) and K(+) homeostasis in plants. Mulberry is not only an important traditional economic woody plant known for its leaves, which are the exclusive food source of the silkworm Bombyx mori, but it can also adapt to many different adverse conditions, including saline environments. However, little is known about the NHXs in this important perennial tree. In this study, we identified and cloned seven putative NHX gene family members from Morus atropurpurea based on a genome-wide analysis of the Morus genome database. A phylogenetic analysis and genomic organization of mulberry NHXs suggested that the mulberry NHX family forms three distinct subgroups. Transcriptome data and real-time PCR of different mulberry varieties under normal culture conditions revealed that the mulberry NHX family has a different tissue-specific pattern in the two mulberry species. The MaNHX genes' expression analyses under different stresses (salt and drought) and signal molecules (abscisic acid, salicylic acid, hydrogen peroxide and methyl jasmonate) revealed that MaNHXs not only could be induced by salt, drought and abscisic acid as describe in the literature, but were also induced by other signal molecules, which indicated that MaNHX members exhibited diverse and complicated expression patterns in different mulberry tissues under various abiotic stresses, phytohormones and plant signaling molecules. Our results provide some insights into new and emerging cellular and physiological functions of this group of H(+)-coupled cation exchangers, beyond their function in salt tolerance, and also provide the basis for further characterizations of MaNHXs' physiological functions.
钠/氢交换体（NHXs）在植物细胞pH值以及钠和钾的稳态维持中发挥着重要作用。桑树不仅是一种重要的传统经济木本植物，以其叶片作为家蚕唯一的食物来源而闻名，而且它还能适应多种不同的逆境条件，包括盐渍环境。然而，对于这种重要的多年生树木中的NHXs却知之甚少。在本研究中，我们基于对桑属基因组数据库的全基因组分析，从紫果桑中鉴定并克隆了7个假定的NHX基因家族成员。桑树NHXs的系统发育分析和基因组结构表明，桑树NHX家族形成了三个不同的亚组。正常培养条件下不同桑树品种的转录组数据和实时PCR结果显示，桑树NHX家族在两个桑树种中具有不同的组织特异性模式。MaNHX基因在不同胁迫（盐和干旱）和信号分子（脱落酸、水杨酸、过氧化氢和茉莉酸甲酯）处理下的表达分析表明MaNHXs不仅如文献中所述能被盐、干旱和脱落酸诱导，还能被其他信号分子诱导，这表明MaNHX成员在各种非生物胁迫、植物激素和植物信号分子作用下，在不同桑树组织中表现出多样而复杂的表达模式。我们的研究结果为这组H⁺偶联阳离子交换体除耐盐功能之外新出现的细胞和生理功能提供了一些见解，也为进一步阐明MaNHXs的生理功能奠定了基础。
