Effects of Exogenous ABA and 6-BA on Protein Content and Grain Filling Process in Different Types of Stay-Green Wheat

Abstract

This study aimed to understand the grain filling process and protein biosynthesis in grain of stay-green wheat in response to exogenous hormones. At blooming stage, plants of Wennong 6(stay-green cultivar) and Jimai 20(control) were sprayed with 10 mg L-1 abscisic acid(ABA) and 6-benzyladenine(6-BA) for four days. Compared with Jimai 20, Wennong 6 had longer grain-filling duration(t3) and the active growth phase(D), higher mean grain-filling rate(Gmean) and maximum grain-filling rate(Gmax), larger thousand-grain weight(TGW), and greater grain yield(GY). All parameters for grain filling were higher in superior grain than in inferior grain. Gmean, Gmax, TGW, and GY were promoted by ABA or 6-BA treatment in both cultivars. However, the effects of exogenous hormones on t3 and D were interacted with grain position in a panicle and genotype. Exogenous ABA and 6-BA treatment obviously increased protein content at 35 days after anthesis(DAA). The glutenin contents in ABA-treated and 6-BA-treated Wennong 6 significantly increased at 35 DAA; however, those in Jimai 20 decreased at 35 DAA. Exogenous ABA increased endogenous zeatin(ZR) content from 7 DAA to 21 DAA. In Wennong 6, GA3 content in superior grain was significantly decreased from 7 DAA to 21 DAA by 6-BA treatment, however, its content in inferior grain was enhanced. In both cultivars, ap-plication of ABA and 6-BA resulted in significant increases of endogenous auxin(IAA) and ABA contents from 7 DAA to 21 DAA, along with significant enhancement of glutamine synthetase(GS) activity.