Liu Zhujiang, Liu Panpan, Qi Dongmei, Peng Xianjun, Liu Gongshe
Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, People's Republic of China; University of the Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
Key Laboratory of Plant Resources, Institute of Botany, The Chinese Academy of Sciences, Beijing, 100093, People's Republic of China.
J Plant Physiol. 2017 Apr;211:90-99. doi: 10.1016/j.jplph.2016.12.014. Epub 2017 Jan 19.
Leymus chinensis is an important perennial forage grass natively distributed in the Eurasian Steppe. However, little is known about the molecular mechanism of its adaptation to extreme environmental conditions. Based on L. chinensis cold-treated sequence database, a highly expressed S-adenosylmethionine decarboxylase gene (LcSAMDC1) was isolated from L. chinensis. Gene structure analysis showed that LcSAMDC1 has two introns and three exons as well as three non-overlapping ORFs in its mRNA sequence. One hour of cold exposure caused a significant up-regulation of LcSAMDC1, while abscisic acid (ABA), salt, and osmotic stresses slightly induced its expression. Analysis of gene expression in different tissues showed that LcSAMDC1 was expressed ubiquitously, with higher levels in the young spike and rhizome. Overexpression of the main ORF of LcSAMDC1 in transgenic Arabidopsis promoted increased tolerance to cold and salt stress relative to wild type Arabidopsis. The concentration of polyamines, proline, and chlorophyll was significantly higher in transgenic Arabidopsis, and spermine of polyamines increased more under cold than under salt stress. These results suggest that LcSAMDC1 was induced in response to cold and could influence the production of polyamines involved in stress tolerance of L. chinensis. Moreover, transgenic expression of LcSAMDC1 could be used to improve the abiotic resistance of crops.
羊草是一种重要的多年生牧草，原产于欧亚草原。然而，关于其适应极端环境条件的分子机制知之甚少。基于羊草冷处理序列数据库，从羊草中分离出一个高表达的S-腺苷甲硫氨酸脱羧酶基因（LcSAMDC1）。基因结构分析表明，LcSAMDC1在其mRNA序列中有两个内含子和三个外显子以及三个不重叠的开放阅读框。冷暴露1小时导致LcSAMDC1显著上调，而脱落酸（ABA）、盐和渗透胁迫轻微诱导其表达。不同组织中的基因表达分析表明，LcSAMDC1在各处均有表达，在幼穗和根茎中表达水平较高。相对于野生型拟南芥，在转基因拟南芥中过表达LcSAMDC1的主要开放阅读框可提高对冷和盐胁迫的耐受性。转基因拟南芥中多胺、脯氨酸和叶绿素的浓度显著更高，多胺中的精胺在冷胁迫下比在盐胁迫下增加更多。这些结果表明，LcSAMDC1在冷胁迫下被诱导，并可能影响参与羊草胁迫耐受性的多胺的产生。此外，LcSAMDC1的转基因表达可用于提高作物的非生物抗性。
