Effects of exogenous gibberellic acid and abscisic acid on germination, amylases, and endosperm structure of germinating wheat seeds

Although there have been many studies on wheat seed germination, little information is available concerning the endosperm structural changes affected by exogenous hormones. In this paper, a strong gluten wheat variety, Yannong 19, and a weak gluten variety, Yangmai 13, were used to analyse the effects of GA(3) and ABA on seed germination and structural changes. Soaking seeds in GA3 significantly improved germination and seedling height and accelerated the alpha-amylase activity at 1-3 days after imbibition (DAI). Starchy endosperm was consumed rapidly at 3-5 DAI and mostly depleted at 7 DAI. Seeds treated with GA(3) could enhance the speed of amyloplast degradation while ABA had the opposite effects. Protein storage vacuoles (PSVs) and cell nucleus in the aleurone layer cells showed obvious structural changes at 5 DAI. Their degradation occurred later and slower than that of the starchy endosperm, and these processes were accelerated by GA(3) but lowered by ABA. There were differences in response to GA(3) and ABA between the two varieties. The findings will be helpful to further clarify the relationship between structure and function of germinating wheat seeds.