Ethylene Enhances Seed Germination and Seedling Growth Under Salinity by Reducing Oxidative Stress and Promoting Chlorophyll Content via ETR2 Pathway

Yue Wang; Pengfei Diao; Lingqi Kong; Ruonan Yu; Man Zhang; Tiantian Zuo; Yanyan Fan; Yiding Niu; Fang Yan; Hada Wuriyanghan

doi:10.3389/fpls.2020.01066

Ethylene Enhances Seed Germination and Seedling Growth Under Salinity by Reducing Oxidative Stress and Promoting Chlorophyll Content via ETR2 Pathway

Front Plant Sci. 2020 Jul 16:11:1066. doi: 10.3389/fpls.2020.01066. eCollection 2020.

Authors

Yue Wang^{1

2}, Pengfei Diao^{1

2}, Lingqi Kong³, Ruonan Yu^{1

2}, Man Zhang^{1

2}, Tiantian Zuo^{1

2}, Yanyan Fan^{1

2}, Yiding Niu^{1

2}, Fang Yan^{1

2}, Hada Wuriyanghan^{1

2}

Affiliations

¹ Key Laboratory of Forage and Endemic Crop Biotechnology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, China.
² State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Sciences, Inner Mongolia University, Hohhot, China.
³ Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China.

Abstract

Alfalfa (Medicago sativa L.) is an important forage, and salinity is a major stress factor on its yield. In this study, we show that osmotic stress retards alfalfa seedling growth, while ionic/oxidative stress reduces its seed germination. Ethylene treatment can recover the germination rate of alfalfa seeds under salt stress, while ethylene inhibitor silver thiosulfate exacerbates salt effects. ETH reduces the accumulation of MDA and H₂O₂ and increases POD activity. ETH and ACC improve the salt tolerance of alfalfa by increasing proline content under salt stress. In contrast, STS inhibits alfalfa seed germination by reducing POD activity. NaCl treatment reduces chlorophyll content in alfalfa leaves, while ETH and ACC can increase the chlorophyll content and promote seedling growth. ETH promotes the growth of alfalfa in saline condition by reducing the expression of MsACO and MsERF8 genes, while increases its germination rate by upregulating MsERF11 gene. Silencing of MsETR2, a putative ethylene receptor gene in alfalfa, abolishes ethylene triggered tolerance to salt stress. In summary, we show that ethylene improves salt tolerance in alfalfa via MsETR2 dependent manner, and we also analyze the regulatory mechanism of ethylene during germination of alfalfa seeds under salt stress.

Keywords: MsETR2; alfalfa; ethylene; salinity; seed germination; seedling growth.