| In this study, two millet cultivars JinguA2 and Jingu 45 were used as the material for the investigation of the germination differences between different varieties of millet and GA mechanism in the process of millet germination. In order to study the germination differences of Jingu42 and Jingu 45 from the substance metabolism and molecular levels, the metabolic changes of soluble proteins and carbohydrates of millet during seed germination were determined, and the expression patterns of GA metabolic enzyme genes were detected by using real-time PCR. Moreover, Jin gu42 and Jingu45 were treated with 250mg/L gibberellin (GA3) and 50mg/L paclobutrazol (PP333) to study the influence of seed soaking with GA3 and PP333 on major changes of material storage during seed germination and the expression level of GA metabolic enzyme genes. The results showed that:1. In the process of millet seed germination, the starch content decreased, but the amylase activity and sugar content were gradually increased. Soluble protein content and soluble sugar content were reducing at first time, then rising. The absorption rate of Jingu45 is greater than Jingu42 during germination. The starch content of Jingu45 is higher than Jingu42. The soluble protein contents of Jingu42 were higher than Jingu45, but the amylase activity not, while the soluble sugar contents were less than 45 before 24h.2. We intensively screened and identified 26 candidate genes encoding the seven GA metabolic enzymes from the millet genome. The results indicated that millet genome contains three KO, seven GA2ox, and four CPS, KS, GA20ox respectively, two KAO and GA3ox respectively. And most of them are arranged separately on the millet genome. Expression analysis showed that transcripts of 18 GA metabolic enzyme genes could be detected during millet seed germination, and the expression patterns of these genes were different during seed germination in Jingu42 and Jingu45.3. We could calculate that the SiCPS3, SiCPS4, SiKS4, SiGA20ox3, SiGA3ox2, SiGA2ox5 and other genes play an important role in the germination process of millet through the phylogenetic analysis. According to the expression patterns analysis of GA metabolic enzyme genes, we knew that the relative gene expression levels of SiCPS3ã€SiKS4ã€SiGA2Oox3ã€SiGA3ox2 in Jingu45 were higher than Jingu42 during germination,while the SiGA2ox5 was not.4. Gibberellin could promote the seed bourgeon and seedling growth of millet, but reduce the root-shoot ratio. The paclobutrazol had opposite effects, it inhibited seed germination, but promoted the millet root growth and improved the shoot ratio significantly. The promotion effect of GA3 on seed germination of Jingu42 was significantly greater than Jingu45, while the effect of PP333 on Jingu42 was much less than Jingu45.5. Gibberellin could significantly promote the use of the storage material in the millet seed germination. After GA3 soaking treatment, the amylase activity, protein and soluble sugar contents increased, and the use of starch enhanced. However, PP333 soaking inhibited the amylase activity, reduced the use of starch and the content of soluble protein and sugar, but increased the accumulation of soluble sugar.6. PP333 inhibited the transcription of SiKS4 and SiGA3ox2, and increased the expression of these genes such as SiGA20ox4. The expression levels of these genes such as SiKS4, SiGA20ox4 were inhibited by GA3, and GA3 improved the expression levels of SiCPS2, SiGA20ox3, SiGA2ox5, SiGA2ox6 and other genes. In addition, the change of expression levels of GA metabolism gene in Jingu42 were different with Jingu 45... |
