【摘要】 S-腺苷甲硫氨酸脱羧酶（SAMDC）在植物抵御逆境胁迫中发挥着重要作用。通过分子生物学技术克隆得到一个全长为1559 bp的白三叶S-腺苷甲硫氨酸脱羧酶基因,并命名为TrSAMDC1。对该序列进行生物信息学分析表明:TrSAMDC1开放阅读框长度为1077 bp,编码358个氨基酸;预测其编码的蛋白为不稳定的亲水性蛋白,无跨膜结构,无信号肽,二级结构的主要构件为无规则卷曲,三级结构为同源二聚体,可能定位于细胞质中;系统进化树表明TrSAMDC1与其他豆科植物SAMDC亲缘关系很近,在进化上高度保守。分析该基因在重金属镉（CdSO₄）、低温（4℃）、高温（35℃）、干旱（PEG-6000）和盐（NaCl）等非生物胁迫以及100μmol·L^-1脱落酸（ABA）和1 mmol·L^-1生长素（IAA）等激素处理下的表达模式发现TrSAMDC1的表达具有组织器官和时空特异性:所有处理都能显著上调叶片的相对表达量,并且在大多数处理12 h后达到峰值。而根系表达量虽较对照有差异,但对各种处理的敏感程度显著低于叶片。推测该基因能在调节植物的生长发育以及植物应对非生物胁迫尤其是高温和重金属镉胁迫中发挥重要作用,以上结果为进一步研究该基因奠定了基础。更多还原

【Abstract】 S-adenosyl-L-methionine decarboxylase（SAMDC） plays an important role in plant abiotic stress resistance. In this study, a 1559 bp full-length SAMDC gene of white clover（Trifolium repens） were cloned by molecular biology technology and named TrSAMDC1. Bioinformatics analysis indicated that TrSAMDC1 has an open reading frame of 1077 bp. The TrSAMDC1 gene encodes an unstable hydrophilic protein of 358 amino acids without transmembrane structure and acting as a signal peptide, which might be located in the cytoplasm. The main components of the secondary structure were a random coil, and the tertiary structure was a homologous dimer. The phylogenetic tree indicates that TrSAMDC1 was closely related to SAMDC of other Leguminosae and highly conserved in evolution. The expression patterns of TrSAMDC1 demonstrates tissue, organ and spatio-temporal specificity under abiotic stress including heavy metal cadmium（CdSO₄）, low temperature（4 ℃）, high temperature（35 ℃）, drought（PEG-6000） and salt（NaCl） and hormone treatments [such as 100 μmol·L^-1 abscisic acid（ABA） and 1 mmol·L^-1 auxin（IAA）]. All treatments could significantly up-regulate the relative expression of leaves TrSAMDC1, and reached the peak after 12 h in most treatments. Although the roots expression of TrSAMDC1 was different from that of control, the sensitivity of roots was significantly lower than that of leaves. The results showed that the TrSAMDC1 could regulated growth and development and responses abiotic stress, especially to high temperature and heavy metal cadmium stress.更多还原