REGULATION OF TUBEROUS ROOT FORMATION BY CDK-ACTIVATING KINASE IN SWEET POTATO

克隆了CDK激活激酶和细胞周期蛋白H的两个cDNA，分别命名为Ipoba；CDKD；1和Ipoba；CycH；1。推导出的Ipoba；CDKD；1的氨基酸序列包含一个ATP结合部位、一个激酶活性部位和T-环内保守的苏氨酸残基。推导的Ipoba；CycH；1的氨基酸序列含有N-末端结构域。虽然Ipoba；CDKD；1基因在所有器官中都有表达，但在块茎中表达水平最低。不同器官转录产物的相对丰度变化不大。蔗糖、ABA和细胞分裂素水平在块根形成过程中呈上升趋势。因此，这些信号分子对Ipoba；CDKD；1和Ipoba；CycH；1表达的影响：1.蔗糖溶液使Ipoba；CDKD；1的表达增加，而对Ipoba；CycH；1的表达无明显影响。ABA诱导Ipoba；CDKD；1的表达，但不影响Ipoba；CycH；1的表达。苄基腺嘌呤可降低Ipoba；CDKD；1mRNA的相对含量，而增加Ipoba；CycH；1mRNA的相对含量。蔗糖拮抗苯基腺嘌呤对Ipoba；CDKD；1基因表达的抑制作用。当添加蔗糖时，苄基腺嘌呤可促进Ipoba；CycH；1的表达。这些结果表明，细胞增殖是通过改变蔗糖、ABA和细胞分裂素的浓度来调节CDK激活的激酶和细胞周期蛋白H基因的表达而实现的。

Two cDNAs for a CDK-activating kinase and a cyclin H were cloned and designated Ipoba; CDKD; 1 and Ipoba; CycH; 1, respectively. The deduced amino acid sequences for Ipoba; CDKD; 1 contained an ATP-binding site, an kinase active-site and the conserved threonine residue within the T-loop. The deduced amino acid sequences for Ipoba; CycH; 1 contained N-terminal domain. Ipoba; CDKD; 1 transcript was detected in tuberous roots with the lowest level, although the gene was expressed in allorgans. There was little variety found among the relative abundance of transcripts in different organs. The levels of sucrose, ABA and cytokinins increase in the process of tuberous root formation. Therefore, the effect of these signal molecules on the expression of both Ipoba; CDKD; 1 and Ipoba; CycH; 1. The expression of Ipoba; CDKD; 1 increased by application of sucrose solution, while the expression of Ipoba; CycH; 1 was not significantly affected by sucrose. ABA induced the expression of Ipoba; CDKD; 1, whereas the expression of Ipoba; CycH; 1 was not influenced by ABA. The relative amount of Ipoba; CDKD; 1 mRNA was reduced by benzyladenine, while benzyladenine increased the relative amount of Ipoba; CycH; 1 mRNA. Sucrose antagonized the inhibitory effect of benzyladenine for Ipoba; CDKD; 1 gene expression. Benzyladenine enhanced the expression of Ipoba; CycH; 1 when sucrose was supplemented. These results suggested that cell proliferation was controlled via regulation of CDK-activating kinase and cyclin H gene expression by alterations in the concentration of sucrose, ABA and cytokinin.