Drought tolerance in alfalfa (Medicago sativa L.) varieties is associated with enhanced antioxidative protection and declined lipid peroxidation

Cuimei Zhang; Shangli Shi; Zhen Liu; Fan Yang; Guoli Yin

doi:10.1016/j.jplph.2018.10.023

Drought tolerance in alfalfa (Medicago sativa L.) varieties is associated with enhanced antioxidative protection and declined lipid peroxidation

J Plant Physiol. 2019 Jan:232:226-240. doi: 10.1016/j.jplph.2018.10.023. Epub 2018 Oct 31.

Authors

Cuimei Zhang¹, Shangli Shi², Zhen Liu¹, Fan Yang¹, Guoli Yin¹

Affiliations

¹ College of Grassland Science, Key Laboratory of Grassland Ecosystem (Ministry of Education), Pratacultural Engineering Laboratory of Gansu Province, Sino-U.S. Centers for Grazing Land Ecosystem Sustainability, Gansu Agricultural University, Lanzhou, 730070, China.
² College of Grassland Science, Key Laboratory of Grassland Ecosystem (Ministry of Education), Pratacultural Engineering Laboratory of Gansu Province, Sino-U.S. Centers for Grazing Land Ecosystem Sustainability, Gansu Agricultural University, Lanzhou, 730070, China. Electronic address: shishl@gsau.edu.cn.

PMID: 30537610
DOI: 10.1016/j.jplph.2018.10.023

Abstract

Drought stress is considered the most adverse factor restricting plant survival, growth, and productivity. The identification of the key adaptive mechanisms to drought stress is essential to enhance the drought resistance of plants. In this study, differential responses of three alfalfa varieties to drought, including Medicago sativa L. cv. Longzhong (drought-tolerant), Longdong (moderate drought-tolerant), and Gannong No. 3 (drought-sensitive), were comparatively studied at morphological, physio-biochemical, and transcriptional levels after a 12-day period of drought stress simulated by -1.2 MPa polyethylene glycol (PEG-6000). The results showed that prolonged drought stress dramatically decreased growth and photosynthetic capacity of three alfalfa varieties while it increased the accumulation of malondialdehyde (MDA), reactive oxygen species (ROS), osmolytes and antioxidants including reduced ascorbate and glutathione, ascorbate peroxidase (APX) activities, and gene expression of antioxidative enzymes (MsCu/Zn-SOD, MsFeSOD, MtPOD, MsGPX, MsAPX, MsMDAR, MtDHAR, and MsGR). Nine days of treatment and some key traits, including the maximum quantum yield of photosystem II (F_v/F_m), the levels of MDA, O₂^-, and H₂O₂, the redox states of ascorbate and glutathione, APX activity, and the transcript levels of MsFeSOD, MsGR, and MsMDAR, might contribute to differentiating the drought stress tolerance in alfalfa. Overall, drought-tolerant Longzhong showed the highest water retention, photosynthetic performance, and osmoregulation capacity, the lowest lipid peroxidation, and the highest antioxidant enzyme activities and gene expression, which were mainly involved in the ascorbate-glutathione cycle to maintain the balance between the generation and scavenging of intracellular ROS. These findings highlight that enhanced antioxidative protection and declined lipid peroxidation play an important role in alfalfa tolerance against drought.

Keywords: Alfalfa; Antioxidative protection; Ascorbate-glutathione cycle; Differential response; Drought stress; Photosynthetic capacity.

MeSH terms

Antioxidants / metabolism*
Antioxidants / physiology
Dehydration
Lipid Peroxidation*
Medicago sativa / metabolism*
Medicago sativa / physiology
Photosynthesis
Photosystem II Protein Complex / metabolism
Reactive Oxygen Species / metabolism

Substances

Antioxidants
Photosystem II Protein Complex
Reactive Oxygen Species