Effects of GABA and Vigabatrin on the Germination of Chinese Chestnut Recalcitrant Seeds and Its Implications for Seed Dormancy and Storage

Abstract

Recalcitrant chestnut seeds are rich in γ-aminobutyric acid (GABA), which negatively regulates adventitious root development by altering carbon/nitrogen metabolism. However, little is known regarding the role of this metabolite in chestnut seeds. In this study, we investigated the effects of GABA changes on the germination of chestnut seeds treated with exogenous GABA and vigabatrin (VGB, which inhibits GABA degradation). Both treatments significantly inhibited seed germination and primary root growth and resulted in the considerable accumulation of H2O2, but the endogenous GABA content decreased before germination at 48 h. Soluble sugar levels increased before germination, but subsequently decreased, whereas starch contents were relatively unchanged. Changes to organic acids were observed at 120 h after sowing, including a decrease and increase in citrate and malate levels, respectively. Similarly, soluble protein contents increased at 120 h, but the abundance of most free amino acids decreased at 48 h. Moreover, the total amino acid levels increased only in response to VGB at 0 h. Accordingly, GABA and VGB altered the balance of carbon and nitrogen metabolism, thereby inhibiting chestnut seed germination. These results suggested that changes to GABA levels in chestnut seeds might prevent seed germination. The study data may also help clarify the dormancy and storage of chestnut seeds, as well as other recalcitrant seeds.

The versatile GABA in plants

“… 34 Exogenous GABA prevents seed germination and primary root growth in the recalcitrant seeds of Chinese chestnut by altering the balance of carbon and nitrogen metabolism to maintain the dormancy and storage of these seeds. 50 Similarly, a high GABA content also inhibits adventitious root growth. For example, adventitious root growth of poplar is inhibited if the GABA level is increased in poplar lines by inhibition of α-ketoglutarate dehydrogenase activity , 51 overexpression of PagGAD2 52 or exogenous GABA application.…”

Combined physiological and metabolomic analysis reveals the effects of different biostimulants on maize production and reproduction

“…Similar findings also appeared in the germination process of millet seeds ( Sharma et al., 2018 ). GABA provides the carbon skeleton for the TCA cycle, which aids in seed germination ( Du et al., 2020 ). In this study, the content of ornithine, a precursor of GABA synthesis, was significantly down-regulated by 65.7% in humic acid treatment (File S3).…”

Comparative Metabolome Analyses of Chinese Hickory Nut Kernels Highlight The Importance of Allocation Shift and Accumulation on Primary and Secondary Metabolites During In-Situ Germination

“…The balance of carbon and nitrogen in seeds affects seed development, maturation and germination statuses [6,[56][57]. During seed germination, the disturbance of endogenous γaminobutyric acid or activation of α-amylase activities contributes to starch hydrolysis [7,33,[57][58]. Carbohydrate degradation which accompanied by the accumulation of monosaccharides is expected to support germination [33].…”

“…In-situ germination led to severe annual loss of major crops worldwide. For example, occurrence of precocious germination in rice field of South China could reach up to over 6% field acreage for conventional rice and be up to 20% for hybrid rice [7]. Seed pre-germination in spikes occurs in almost every wheat growing region in the world and more than 4% on grain kernel is classified as not suitable for human consumption, which often used only as animal feedstock [5,8].…”