赤霉素氧化酶PsGA20ox基因参与低温诱导的牡丹内休眠解除

The Study of PsGA20ox Gene Participating in Endo-dormancy Release of Flower Buds by Chilling Treatment in Tree Peony

为明确在花芽内休眠进程中牡丹赤霉素氧化酶PsGA20ox基因与内源GA3含量的相关性,以454测序筛选到的PsGA20ox基因部分cDNA序列为基础,经RACE扩增和序列拼接后得到1 391 bp全长cDNA序列,包括16 bp 5'UTR区,212 bp 3'UTR区,17 bp的PolyA和1 146 bp编码区,编码区编码381个氨基酸。同源性分析表明,PsGA20ox与杨树GA20ox同源性最高,为77.6%。表达分析结果表明,在内休眠的前期阶段,PsGA20ox基因的表达水平随着低温处理天数增加而升高,低温处理14 d时PsGA20ox基因表达量最高。酶联免疫反应结果表明,不同低温处理的牡丹花芽内源GA3的含量的变化趋势与PsGA20ox基因表达模式相似。相关分析表明,在鲁荷红休眠解除过程中PsGA20ox基因表达水平与内源GA3含量呈显著正相关。低温累积可诱导PsGA20ox基因的表达,PsGA20ox基因通过调节内源赤霉素含量促进花芽休眠解除。

In order to investigate the correlation between the expression level of PsGA20ox gene and endogenous GA3contents during dormancy release in tree peony,using tree peony Lu hehong as plant materials,RACE PCR amplification was carried out based on the obtained partial cDNA sequence by 454 sequencing.The results of fragment assembly indicated that full-length cDNA sequence of the PsGA20ox gene was 1391 bp including a 1 146bp open reading frame（ ORF）,16 bp 5＇terminal UTR and 212 bp 3＇terminal UTR followed by 17 bp polyA tail.Analysis of the ORF sequence showed that the ORF of PsGA20ox encoded a protein of 381 amino acids.The result of sequence homology indicated that PsGA20ox protein had relatively highly identity with that of poplar,and there was an identity of 77.6%.The results of RT-PCR indicated that the expression of PsGA20ox continuously increased in the tree peony flower buds during the early stage of dormancy release（ from 0 to 14 d chilling treatment）,followed by gradually decrease until 28 d,and the expression level of all treatment points were more than that of 0 d.The change trend of the endogenous GA3content by enzyme-linked immunoassay was similar to that of PsGA20ox expression.Significant positive correlation between the expression level of PsGA20ox and the contents of endogenous GA3was obtained.These results indicated that PsGA20ox played an important role to accelerate dormancy release by regulating the synthesis of endogenous GA3.