Comparative proteomic analysis of alfalfa revealed new salt and drought stress-related factors involved in seed germination

Abstract

Salinity and drought are two major environmental factors that limit the growth and yield of many forage crops in semi-arid and arid regions. Alfalfa (Medicago sativa L.) is one of the most important forage crops in many countries. We aim to investigate the molecular mechanisms of alfalfa in response to salt and drought stresses in this study. Physiological and proteomic analyses were applied to examine the Zhongmu NO.3 alfalfa seed germination stage with 200 mM NaCl and 180 g·L polyethylene glycol (PEG) treatments. The germination ability of the seed and the accumulation of osmotic solutes were quite different between the NaCl and PEG treatments. More than 800 protein spots were detected by proteomics technology on two-dimensional electrophoresis (2-DE) gels. The abundance of twenty-eight proteins were decreased or increased after salt and drought stress. Seventeen of these proteins were identified and classified into six functional categories through mass spectrometry (MS). The six groups involved in salt- and PEG-mediated stress included defense response, energy metabolism, protein synthesis and degradation, oxidative stress, carbohydrate metabolism-associated proteins, and unknown proteins. We discovered that some proteins related to carbohydrate metabolism and energy production increased in abundance under salt- and PEG-mediated drought stress. This demonstrates a common mechanism of energy consumption during abiotic stresses. Further study of these proteins with unknown function will provide insights into the molecular mechanisms of abiotic stress and the discovery of new candidate markers.

Salt Stress Represses Soybean Seed Germination by Negatively Regulating GA Biosynthesis While Positively Mediating ABA Biosynthesis

“…It is well-known that salt inhibits soybean seed germination and post-germinative growth, which eventually leads to decreases in yield ( Hamayun et al, 2015 ). Previous investigations and the present study showed that NaCl treatment caused cellular oxidative stress ( Figure 2 ; Liang et al, 2003 ; Zhu, 2016 ; Farhangi-Abriz and Torabian, 2017 ), and the level of cellular oxidative pressure is further associated with the activity of seed germination ( Ma et al, 2017 ). In the past decade, soybean salt tolerance-related quantitative trait loci and some key proteins have been identified over the past few decades ( Xu et al, 2011 ; Guan et al, 2014 ; Kan et al, 2015 ).…”

Combined Proteomics and Metabolism Analysis Unravels Prominent Roles of Antioxidant System in the Prevention of Alfalfa (Medicago sativa L.) against Salt Stress

“…Quantitative PCR (qPCR) was performed on a Realplex 4 Master Cycler using a gene-specific primer (Table S1) using Super Real PreMix Plus with Syber Green 1 (TIANGEN Biotech., Beijing, China). Relative gene expression was assessed using a comparative cycle threshold method [40]. The relative gene expression was calculated as follows: 2 −∆∆CT (∆CT = CT, gene of interest -CT versus actin) as described by [41], where the actin gene was used as a reference.…”

Physiological and Proteomic Responses of Contrasting Alfalfa (Medicago sativa L.) Varieties to PEG-Induced Osmotic Stress

“…Moreover, Yacoubi et al (2011 , 2013 ) investigated the impact of PEG imbibition on the alfalfa proteome during seed germination. Ma et al (2017) reported the proteomic changes of germinating alfalfa seeds under PEG and NaCl stresses. Previously reported alfalfa proteomics studies were mainly using two-dimensional gel electrophoresis (2-DE) ( Aranjuelo et al, 2011 ; Yacoubi et al, 2011 ; Yacoubi et al, 2013 ; Atikur et al, 2016 ; Ma et al, 2016 , 2017 ).…”

“… Ma et al (2017) reported the proteomic changes of germinating alfalfa seeds under PEG and NaCl stresses. Previously reported alfalfa proteomics studies were mainly using two-dimensional gel electrophoresis (2-DE) ( Aranjuelo et al, 2011 ; Yacoubi et al, 2011 ; Yacoubi et al, 2013 ; Atikur et al, 2016 ; Ma et al, 2016 , 2017 ). However, 2D-gel-based approaches had a disadvantage in the identification and accurate quantification of proteins from multiple samples.…”