Diethyl Aminoethyl Hexanoate Priming Ameliorates Seed Germination via Involvement in Hormonal Changes, Osmotic Adjustment, and Dehydrins Accumulation in White Clover Under Drought Stress

Abstract

Drought is a serious outcome of climate change reducing the productivity of forage species under arid and semi-arid conditions worldwide. Diethyl aminoethyl hexanoate (DA-6), a novel plant growth regulator, has proven to be involved in the amelioration of critical physiological functions in many agricultural crops under various abiotic stresses, but the role of the DA-6 in improving seed germination has never been investigated under drought stress. The present study was carried out to elucidate the impact of the DA-6 priming on seeds germination of white clover under drought stress. Results showed that seed priming with the DA-6 significantly mitigated the drought-induced reduction in germination percentage, germination vigor, germination index, seed vigor index, root length, shoot length, and fresh weight after 7 days of seed germination. The DA-6 significantly increased the endogenous indole-3-acetic acid, gibberellin, and cytokinin content with marked reduction in abscisic acid content in seedlings under drought stress. In addition, the DA-6 significantly accelerated starch catabolism by enhancing the activities of hydrolases contributing toward enhanced soluble sugars, proline content and ameliorated the antioxidant defense system to enhance the ability of reactive oxygen species scavenging under drought stress. Furthermore, exogenous DA-6 application significantly increased dehydrins accumulation and upregulated transcript levels of genes encoding dehydrins (SK2, Y2SK, or DHNb) during seeds germination under water deficient condition. These findings suggested that the DA-6 mediated seeds germination and drought tolerance associated with changes in endogenous phytohormones resulting in increased starch degradation, osmotic adjustment, antioxidants activity, and dehydrins accumulation during seed germination under water deficient condition.

Seed Priming with Chitosan Improves Germination Characteristics Associated with Alterations in Antioxidant Defense and Dehydration-Responsive Pathway in White Clover under Water Stress

“…It has been proven that white clover seed priming with a low concentration of NaCl solution could significantly mitigate adverse effects induced by water stress, including declines in GP, GV, SVI, and radicle length [ 37 ]. Recent research also showed that white clover seeds soaking in an appropriate dose of diethyl aminoethyl hexanoate solution before being geminated under water stress effectively improved germination rate, root length, and shoot length of seedlings [ 23 ]. In addition, seed coating with CTS has been reported to significantly promote GP and seedling growth of hybrid rice under salt stress [ 38 ].…”

“…DHNs quickly accumulate during seed germination or when plants suffer dehydration due to their positive functions as chaperones, ROS scavengers, and osmoprotectants in cells [ 51 ]. Previous study has proven that white clover seed priming with DA-6 significantly mitigated adverse effects of water stress on seed germination and seedling establishment in relation to significant accumulation of DHN and upregulation of Y2K , Y2SK , and SK2 genes encoding different types of DHNs [ 23 ]. Enhanced AnDHN or CaDHN3 expression in Arabidopsis increased seed germination and initial root length under drought stress and also promoted antioxidant capacity to alleviate drought-induced ROS accumulation in seedlings [ 52 , 53 ].…”

“…Seed priming with bioactive compounds or elements such as zinc, γ-aminobutyric acid (GABA), putrescine (Put), diethyl aminoethyl hexanoate (DA-6), or spermidine (Spd) has been proven as an effective way to improve seed germination under normal and stressful conditions [ 19 , 20 , 21 , 22 , 23 ]. Previous studies have found that chitosan-black soybean seed-coat extract exhibited strong antioxidant property, and CTS coating could effectively improve seed germination, seedling growth, and resistance to pests under normal condition [ 24 , 25 , 26 ].…”

Enhanced Adaptability to Limited Water Supply Regulated by Diethyl Aminoethyl Hexanoate (DA-6) Associated With Lipidomic Reprogramming in Two White Clover Genotypes

“…Salt-induced damage in Cassia obtusifolia seedlings could be mitigated by DA-6 application because of enhanced osmolyte accumulation, photosynthesis, and antioxidant defense (Zhang et al, 2016 ). Our recent study also demonstrated that DA-6 improved the seed germination of white clover ( Trifolium repens ) by mediation of endogenous hormones, amylolysis, and dehydrin accumulation under water stress (Hassan et al, 2021 ). However, how reprogramming lipid profile is linked with DA-6-induced drought resistance has not been investigated in plants so far.…”

How Silicon Alleviates the Effect of Abiotic Stresses During Seed Germination: A Review

“…For example, water deficit mediated by PEG treatment triggered an increase in ABA and a decrease in GA in Trifolium repens, impairing seed germination (Hassan et al 2021). When less GA is available under water shortage, reserve mobilization is compromised, because the synthesis of various hydrolytic enzymes is not stimulated (Bewley 2001).…”