The inhibited seed germination by ABA and MeJA is associated with the disturbance of reserve utilizations in Astragalus membranaceus

Nan Yang,Xiaorui Guo,Yan Wu,Xiaohang Hu,Yuehua Ma,Ye Zhang,Hongzheng Wang,Zhonghua Tang

doi:10.1080/17429145.2018.1483034

Abstract

ABSTRACTAstragalus membranaceus is a major traditional Chinese medicinal plant. Here, we investigated the mobilizations of seed reserves during its germination and post-germination growth, as well as the effects of exogenous abscisic acid (ABA) and methyl jasmonate (MeJA). It was found that both starch and protein were rapidly mobilized during the seed germination. However, lipid was mostly utilized during the post-germination. Exogenous ABA and MeJA treatments significantly inhibited the germination and post-germination growth. Meanwhile, the treatments decreased the weight of mobilized seed reserves and seed reserves utilization efficiency, retarded the mobilizations of protein and lipid, and led to excessive consumption of carbon energy. Moreover, the treatments changed fatty acid compositions in cotyledons, with the decreasing of the double bond index and average carbon chain length. This study will help us to understand the inhibition mechanism of exogenous ABA and MeJA on the germination and post-germination growth of A. membranaceus.

Highlights

In the life cycle of a plant, germination is the initial and most crucial stage and determines the establishment and growth of the seedling (Zhang et al 2010)
We investigated the effects of exogenous abscisic acid (ABA) and methyl jasmonate (MeJA) on germination rate, reserves utilization efficiency, content variations of starch, soluble sugar, soluble protein and lipid in cotyledon during the germination and post-germination growth of A. membranaceus
At the 1.5 days after sowing (DAS), the germination percentages were respectively decreased 88% and 95% in ABA and MeJA treatments when compared to the control

Summary

Introduction

In the life cycle of a plant, germination is the initial and most crucial stage and determines the establishment and growth of the seedling (Zhang et al 2010). With the beginning of seed germination, the starch stored in granules and proteins in storage vacuoles are mobilized and respectively converted to soluble sugars and amino acids (Juliano and Varner 1969; Vitale and Hinz 2005). As the other seed reserve, the lipid is stored in oil bodies with the form of triacylglycerol (TAG). The TAGs release free fatty acids, and the free fatty acids sequentially enter the process of β-oxidation and glyoxylate cycle, converting to four-carbon organic acids which are transported into mitochondrion and cytosol for the conversion of sucrose (Graham 2008; Erbas et al 2016). Lipid is known as the most energy-enriched reserve in plant seed. Compared to the hydrolysis of carbohydrate, the complete oxidation of the same weight lipid can produce more than two times of energy (Quettier and Eastmond 2009)

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