外施赤霉素对‘峰后’葡萄坐果及VvAG基因表达的影响

Improvement of fruit set and expression of VvAGs in ‘Fenghou’grapevine with exogenous gibberellin

关键词:  葡萄  坐果  赤霉素(GA₃)  VvAG基因

Key words:  Grapewine(Vitis×Labruscana Bailey)  fruit set  gibberellin  VvAG gene

摘要:

为探明‘峰后’葡萄在赤霉素(GA₃)处理促使葡萄座果率增加原因和VvAG基因在葡萄坐果过程中的作用,在开花前10 d用0.02 mg/g的GA₃和赤霉素合成抑制剂PAC处理葡萄花序并通过石蜡切片观察葡萄早期果实发育结构的变化,通过RT-PCR分析了VvAG基因的表达。结果显示:GA₃处理提高了葡萄座果率,PAC处理则降低座果率,而PAC+GA₃处理可以恢复葡萄正常坐果。GA₃处理在开花后0~10 d幼果纵横径大于对照,而PAC处理则小于对照。进一步分析发现,GA₃处理后中果皮细胞明显大于对照,而PAC处理则小于对照,说明GA₃处理导致开花后0~10 d幼果增大的原因是由于细胞分裂和中果皮细胞增大的缘故。VvAG基因的表达呈现出组织特异性,VvAG2在叶片,茎和卷须中均有少量表达,VvAG1和VvAG3则表达量很低,在花和果实中VvAG1和VvAG2有较高的表达,表明这2个基因对于葡萄花发育和坐果是必需的。VvAG3在花和果实中的表达量相对较低,但在GA₃处理后表达上调;相反,在PAC处理后,VvAG3表达量下调,表明VvAG3在坐果过程中的表达可能受到赤霉素的调控。

Abstract:

GA3 (0.02 mg/g) and PAC (0.02 mg/g) were applied on inflorescence 10 days before anthesis in order to verify the improvement of fruit set and the role of VvAGs gene in fruit set of ‘Fenghou’ grapevine.The early berry development was observed with microscopy.The RT-PCR was used to analyze expression of VvAGs.The result showed that gibberellin improved fruit set percent,but PAC inhibited fruit set.The inhibition was fully reverted by GA3 application.Both Transverse and longitudinal diameters upon GA3 treatment were larger than those of the control at 0-10 days after anthesis.Further analysis showed that cells of mesocarp upon GA3 treatment were larger than those of the control.But PAC treatment had the opposite effect,which might suggest that GA3 improved cell expansion of mesocarp.The expression of VvAGs had a tissue specificity.VvAG2 was expressed in all organs including young and mature leaves,stems and tendrils.The expression of VvAG1 and VvAG3 was extremely low in tissues except inflorescences and fruits.Nevertheless,the expression of VvAG1 and VvAG2 was very high in inflorescences before anthesis and fruits,suggesting that the two genes were necessary for flower development and fruit set.VvAG3's expression was lower than that of other two genes,but GA3 application could elevate the expression,but PAC treatment had reverse effect,indicating that gibberellin might regulate the expression of VvAG3 gene.