【摘要】 F-box蛋白作为SCF(Skp1-Cullin1-F-box)复合体的成员,参与植物生长发育、细胞分裂及植物激素的响应等调控过程。为深入了解大叶落地生根(Kalanchoe daigremontiana)中胎生苗发育的分子机制,利用RACE-PCR技术从大叶落地生根中克隆了1个新的基因Kd FBX(Gen Bank No.KU740356)。该基因具有328个氨基酸残基,分子量为37.72 k D,等电点为4.4,开放阅读框(open reading frame,ORF)长度为987 bp。其蛋白与亚洲棉(Asiatic cotton)、蓖麻(Ricinus communis)等植物的同源性较高,与拟南芥(Arabidopsis thaliana)的进化关系相对接近。实时荧光定量PCR分析表明,该蛋白基因在大叶落地生根的根中表达量最高,且在渗透胁迫(甘露醇)处理过程中下调表达。本研究首次从大叶落地生根中克隆出Kd FBX基因,为进一步探究该基因的功能提供理论依据。更多还原

【Abstract】 F-box protein, as one component of SCF ubiquitin-ligase(skp1-cullin1-F-box) complex, is involved in growth, cell division and hormone responses of plants. To better understand the molecular mechanisms of plantlet formation of Kalanchoe daigremontiana, an F-box protein, Kd FBX(Gen Bank No.KU740356), was cloned using rapid amplification of c DNA ends(RACE) PCR. Kd FBX gene consists of an ORF of 987 bp which was predicted to encode a 382 amino acid residues long protein of 37.72 k D with an isoelectric point of 4.4. Kd FBX showed homology to orthologs from Ricinus communis, Gossypium raimondii and other plants. Phylogenetic analysis showed that Kd FBX protein was most related to Arabidopsis thaliana. No obvious transmembrane region, signal peptide or cleavage were observed. Kd FBX protein was a water-soluble and non-secreted protein that located in the cytoplasm. 247 amino acids of Kd FBX protein were completely matched to the B chain of the ubiquitin ligase substrate complex, and the backbone structure, as well as the side chain structure was reasonable through Ramachandran analysis. Real-time PCR analysis revealed that Kd FBX transcript was expressed highly in root(2.5 times compared to petiole) and down-regulated under osmotic stress. This study characterized the novel Kd FBX gene from K.daigremontiana for the first time, and the results may be useful for further functional determination of this gene.更多还原