Effect Of Shading And Gibberellin On Anthocyanin Accumulation And Activities Of Related Enzymes In Colored-grain Wheat

To understand the pathway of anthocyanin accumulation during grain filling of wheat and its response to light and gibberellic acid (GA), In this experiment, we used four black-grain of D4 Hei, Hei 3, Wumai 526 and Changyi Heimai, five red-gain of D4 Hong, Hong 5, Hong 6, Nongda 3659 and Heixiaomai 76, and one white-grain (control) varieties/lines as the test materials. To investigate the dynamic changes of anthocyanin accumulation and activities of related enzymes in colored grain wheat during grain filling. The main results were as follows.1 Effect of shading post anthesis on anthocyanin accumulation in colored-grain wheatThe effects of treatments T1 and T3 on anthocyanin content were larger than that of treatment T2, indicating that late grain filling period is critical for anthocyanin biosynthesis. The changing degree of anthocyanin content induced by shading varied across varieties with larger changes in red or purple-grain wheats. In the treatment T1, the grains of five red or purple-grain varieties/lines with anthocyanin content about were 1 U g^-1 or even less than 1 U g^-1 were colorless, similar to the white-grain control"Jimai 19". In the treatment T2, the anthocyanin began to be synthesised after the shading was removed in late grain filling period. The anthocyanin contents of four black-grain wheat varieties/lines were significantly reduced in shading treatments, but the absolute content was higher than 2 U g^-1 in the treatment T1.2 Effect of shading post anthesis on the activities of related enzymes in colored-grain wheatIn colored-grain wheat, the activities of plenylalanine ammonialyase (PAL) and chalcone ismoerase(CHI) were low in early grain-filling period, and increased to a higher level in middle to late filling period. However, the activity of polyphenol oxidase (PPO) varied from a high level in early filling period to a low level in middle to late filling period. In the control treatment without shading, the activities of PAL and CHI were positively associated with anthocyanin content at a significant level, indicating that CHI and PAL are the key enzymes in anthocyanin biosynthesis. The PPO activity was negatively correlated with anthocyanin content in black-grain wheat rather than red-grain wheat. Under the shading conditions, the activities of PAL, CHI, and PPO were not closely associated with the anthocyanin content. Therefore, it is inferred that the effect of light on anthocyanin biosynthesis is not based on the direct regulations of PAL, CHI, and PPO activities.3 Effect of spraying gibberellin post anthesis on anthocyanin accumulation in colored-grain wheatThe result of anthocyanin contents and three enzymes activities with spraying different concentrations of exogenous gibberellin analysis indicated that the anthocyanin contents of colored wheat were improved after spraying lower concentrations of gibberellin, while decreased the anthocyanin contents with higher concentrations of gibberellin. In the GA treatment of 0.06 g/kg, the anthocyanin contents of red grain wheat were Significantly decreased than that of the control without spraying gibberellin at 34 days post anthesis , The contents of anthocyanin in four black-grain wheat varieties/lines were significantly reduced, but the changing degree of anthocyanin contents smaller than that of the red grain wheat. However, the anthocyanin contents of colored wheat mostly were Significantly enhanced using the GA treatment of 0.015 g/kg and 0.03 g/kg, the variation of anthocyanin content in the black grain wheat smaller than that of the red grain wheat, At the 16 and 20 days post anthesis, the contents of anthocyanin in color-grain wheat varieties/lines have no difference compared with control, indicating that the late grain filling period is the main period affected by GA.4 Effect of spraying gibberellin post anthesis on the activities of related enzymes in colored-grain wheatThe activities of PAL and CHI in colored grain wheat were significantly improved after spraying lower concentrations of GA, but with increasing concentrations of GA , the Increment of PAL and CHI activity decreased, even showed inhibition. But the change of PPO activities in colored grain wheat is smaller effected by gibberellin. The activities of PAL and CHI in red grain wheat were positively associated with anthocyanin content at a significant level in spraying gibberellin and control, it is inferred that the effect of gibberellin on anthocyanin biosynthesis is associated with the changes of two enzymes activities in red grain wheat. The activities of PAL and CHI in black grain wheat were positively associated with anthocyanin content at a significant level in spraying gibberellin and control, and the PPO activity was negatively correlated with anthocyanin content in black grain wheat. Therefore, it is suggested that the effect of gibberellin on anthocyanin biosynthesis in black grain wheat was based on the regulations of PAL, CHI, and PPO activities.