Molecular cloning and functional analysis of the drought tolerance gene MsHSP70 from alfalfa (Medicago sativa L.)
Heat shock proteins (HSPs) are a ubiquitously expressed class of protective proteins that play a key role in plant response to stressful conditions. This study aimed to characterize and investigate the function of an HSP gene in alfalfa (Medicago sativa). MsHSP70, which contains a 2028-bp open reading frame, was identified through homology cloning. MsHSP70 shares high sequence identity (94.47%) with HSP70 from Medicago truncatula. Expression analysis of MsHSP70 in alfalfa organs revealed a relatively higher expression level in aerial organs such as flowers, stems and leaves than in roots. MsHSP70 was induced by heat shock, abscisic acid (ABA) and hydrogen peroxide. Transgenic Arabidopsis seedlings overexpressing MsHSP70 were hyposensitive to polyethylene glycol (PEG) and ABA treatments, suggesting that exogenous expression of MsHSP70 enhanced Arabidopsis tolerance to these stresses. Examination of physiological indexes related to drought and ABA stress demonstrated that in comparison with non-transgenic plants, T3 transgenic Arabidopsis plants had an increased proline content, higher superoxide dismutase (SOD) activity, and decreased malondialdehyde (MDA) content. Furthermore, higher relative water content (RWC) was detected in transgenic plants compared with non-transgenic plants under drought stress. These findings clearly indicate that molecular manipulation of MsHSP70 in plants can have substantial effects on stress tolerance.
KeywordsHeat shock protein Medicago sativa Stress response Transgenic Arabidopsis
Heat shock protein
Relative water content
Open reading frame
Green fluorescent protein
Quantitative real-time PCR
This work was supported by the National Program on Key Basic Research Project (Grant Number: 2014CB138703-2), the China Agriculture Research System (Grant Number: CARS-35-04) and The Agricultural Science and Technology Innovation Program (Grant Number: ASTIP-IAS14).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
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