牡丹SERK2基因的克隆和花芽休眠进程中细胞分裂频率分析

Cloning of Somatic Embryogenesis Receptor-like Kinase Gene PsSERK2 and Cell Division Rate Analysis During Dormancy Release in Tree Peony(Paeonia suffruticosa)

根据牡丹休眠相关的差减文库中筛选得到的类体细胞胚胎发生受体蛋白激酶基因SERK2的部分cDNA片段,采用RACE技术扩增到5′和3′cDNA片段,通过拼接得到PsSERK2基因2 374 bp的全长cDNA序列,其中5′非编码区(UTR)为158 bp,3′UTR为341 bp,ORF为1 875 bp,编码625个氨基酸。同源性分析得出其与葡萄VvSERK2蛋白同源性最高,为92.95%。PsSERK2在初花期(大风铃期)茎中表达量最高,叶片中最低。Northern杂交和定量PCR结果均表明PsSERK2在低温解除牡丹花芽休眠前期上调表达,而后降低。低温累积过程中,花芽内各个组织细胞分裂频率逐渐增加。推测PsSERK2上调表达促进了休眠花芽的发育,进而促进内休眠的解除。

According to the partial sequences of potential SERK2 gene screened from suppression subtractive hybridization library,two specific primers were designed and used for 5′ and 3′ RACE amplification in this experiment. A 2 374 bp full length cDNA sequence was obtained with 158 bp 5′ untranslated region（UTR）,341 bp 3′ UTR,and contained a complete ORF with 1 875 bp encoding 625 amino acids. The highest homology with PsSERK2 was VvSERK2 in Vitis vinifera with 92.95% similarity. The results of real-time PCR indicated that the highest expression level of PsSERK2 was detected in the elongating stem and the lowest in expanded leaf at the big bell-like flower-bud of tree peony,the early stage of flowering. Northern blot and fluorescence real-time PCR analysis revealed PsSERK2 was up-regulated during early chilling treatment and then declined after dormancy release. Histological observation showed that the cell division rate increased and the number of cells increased gradually during the dormancy of tree peony. Our results indicated that PsSERK2 might promote the postdevelopment of flower organ,and subsequently induce the dormancy release.