Multiple Regulatory Networks Are Activated during Cold Stress in Medicago sativa L.

Qiang Zhou,Wenxian Liu,Qingchuan Yang,Zhipeng Liu,Dong Luo,Yuguo Wu,Zhibiao Nan,Xutian Chai,Yanrong Wang

doi:10.3390/ijms19103169

Abstract

Cultivated alfalfa (Medicago sativa L.) is one of the most important perennial legume forages in the world, and it has considerable potential as a valuable forage crop for livestock. However, the molecular mechanisms underlying alfalfa responses to cold stress are largely unknown. In this study, the transcriptome changes in alfalfa under cold stress at 4 °C for 2, 6, 24, and 48 h (three replicates for each time point) were analyzed using the high-throughput sequencing platform, BGISEQ-500, resulting in the identification of 50,809 annotated unigenes and 5283 differentially expressed genes (DEGs). Metabolic pathway enrichment analysis demonstrated that the DEGs were involved in carbohydrate metabolism, photosynthesis, plant hormone signal transduction, and the biosynthesis of amino acids. Moreover, the physiological changes of glutathione and proline content, catalase, and peroxidase activity were in accordance with dynamic transcript profiles of the relevant genes. Additionally, some transcription factors might play important roles in the alfalfa response to cold stress, as determined by the expression pattern of the related genes during 48 h of cold stress treatment. These findings provide valuable information for identifying and characterizing important components in the cold signaling network in alfalfa and enhancing the understanding of the molecular mechanisms underlying alfalfa responses to cold stress.

Highlights

Cultivated alfalfa (Medicago sativa L.) is one of the most important legume forages in the world and is the fourth most widely grown crop in the United States [1,2,3]
A decrease in chlorophyll content was observed in four groups (C1, C2, C3, and C4, which represent 2 h, 6 h, 24 h, and 48 h, respectively) under cold stress, compared with the control, but a trend appeared after C2 (Figure 1B)
Lipid peroxidation is induced by cold stress in many plants, and malondialdehyde (MDA) content can be used to evaluate the extent of lipid peroxidation, which further reflects the extent of oxidation injury and cellular damage

Summary

Introduction

Cultivated alfalfa (Medicago sativa L.) is one of the most important legume forages in the world and is the fourth most widely grown crop in the United States [1,2,3]. Known as the “Queen of the Forages”, alfalfa provides highly nutritious forage in terms of protein, fiber, vitamins, and minerals for ruminant animals [4]. It has considerable potential as a valuable forage crop for livestock. Alfalfa can improve soil quality, promote wildlife diversity, and provide its own nitrogen fertilizer through symbiotic nitrogen fixation. Fall dormancy (FD) is defined as an adaptive characteristic related to biomass production and winter survival in alfalfa, and it occurs with a decreasing temperature and day length [7]. Understanding the molecular mechanism of cold stress signal transduction pathways is important for breeders to improve the cold tolerance and fall dormancy of alfalfa

Methods

Results

Conclusion