Xia Jinze, Wang Yu, Zhang Tingting, Pan Chengcai, Ji Yiyin, Zhou Yang, Jiang Xingyu
National Center of Technology Innovation for Saline-Alkali Tolerant Rice, College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, China.
Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province, School of Horticulture, Hainan University, Haikou, China.
Front Genet. 2023 Feb 22;14:1145735. doi: 10.3389/fgene.2023.1145735. eCollection 2023.
Nitrogen (N), absorbed primarily as ammonium (NH ) from soil by plant, is a necessary macronutrient in plant growth and development. Ammonium transporter (AMT) plays a vital role in the absorption and transport of ammonium (NH ). Cassava ( Crantz) has a strong adaptability to nitrogen deprivation. However, little is known about the functions of ammonium transporter AMT2 in cassava. The cassava AMT2-type genes were identified and their characteristics were analyzed using bioinformatic techniques. The spatial expression patterns were analyzed based on the public RNA-seq data and their expression profiles under low ammonium treatment were studied using Real-time quantitative PCR (RT-qPCR) method. The cassava genes were transformed into yeast mutant strain TM31019b by PEG/LiAc method to investigate their functions. Seven AMT2-type genes () were identified in cassava and they were distributed on 6 chromosomes and included two segmental duplication events ( and ). Based on their amino acid sequences, seven MeAMT2 were further divided into four subgroups, and each subgroup contained similar motif constitution and protein structure. Synteny analysis showed that two and four genes in cassava were collinear with those in the Arabidopsis and soybean genomes, respectively. Sixteen types of cis-elements were identified in the promoters, and they were related to light-, hormone-, stress-, and plant growth and development-responsive elements, respectively. Most of the genes displayed tissue-specific expression patterns according to the RNA-seq data, of them, three (, , and ) expressions were up-regulated under ammonium deficiency. Complementation experiments showed that yeast mutant strain TM31019b transformed with , , or grew better than untransgenic yeast cells under ammonium deficiency, suggesting that MeAMT2.3, MeAMT2.5, and MeATM2.6 might be the main contributors in response to ammonium deficiency in cassava. This study provides a basis for further study of nitrogen efficient utilization in cassava.
氮（N）主要以铵态氮（NH₄⁺）的形式被植物从土壤中吸收，是植物生长发育所必需的大量营养元素。铵转运蛋白（AMT）在铵态氮（NH₄⁺）的吸收和转运中起着至关重要的作用。木薯（Manihot esculenta Crantz）对缺氮具有较强的适应性。然而，关于木薯中铵转运蛋白AMT2的功能却知之甚少。利用生物信息学技术鉴定了木薯AMT2型基因并分析了其特征。基于公开的RNA测序数据分析了其空间表达模式，并采用实时定量PCR（RT-qPCR）方法研究了它们在低铵处理下的表达谱。通过聚乙二醇/醋酸锂（PEG/LiAc）法将木薯基因转化到酵母突变株TM31019b中以研究其功能。在木薯中鉴定出7个AMT2型基因（MeAMT2.1 - MeAMT2.7），它们分布在6条染色体上，包含两个片段重复事件（MeAMT2.1 - MeAMT2.3和MeAMT2.4 - MeAMT2.5）。基于其氨基酸序列，7个MeAMT2进一步分为4个亚组，每个亚组具有相似的基序组成和蛋白质结构。共线性分析表明，木薯中的2个和4个MeAMT2基因分别与拟南芥和大豆基因组中的基因共线。在MeAMT2基因的启动子中鉴定出16种顺式作用元件，它们分别与光、激素、胁迫以及植物生长发育响应元件相关。根据RNA测序数据，大多数MeAMT2基因表现出组织特异性表达模式，其中，3个MeAMT2（MeAMT2.3、MeAMT2.5和MeAMT2.6）在铵缺乏条件下表达上调。互补实验表明，在铵缺乏条件下，用MeAMT2.3、MeAMT2.5或MeAMT2.6转化的酵母突变株TM31019b比未转基因的酵母细胞生长得更好，这表明MeAMT2.3、MeAMT2.5和MeATM2.6可能是木薯响应铵缺乏的主要贡献者。本研究为进一步研究木薯中氮素的高效利用提供了依据。
