MsZEP, a novel zeaxanthin epoxidase gene from alfalfa (Medicago sativa), confers drought and salt tolerance in transgenic tobacco

Abstract

The zeaxanthin epoxidase gene ( MsZEP ) was cloned and characterized from alfalfa and validated for its function of tolerance toward drought and salt stresses by heterologous expression in Nicotiana tabacum. Zeaxanthin epoxidase (ZEP) plays important roles in plant response to various environment stresses due to its functions in ABA biosynthetic and the xanthophyll cycle. To understand the expression characteristics and the biological functions of ZEP in alfalfa (Medicago sativa), a novel gene, designated as MsZEP (KM044311), was cloned, characterized and overexpressed in Nicotiana tabacum. The open reading frame of MsZEP contains 1992 bp nucleotides and encodes a 663-amino acid polypeptide. Amino acid sequence alignment indicated that deduced MsZEP protein was highly homologous to other plant ZEP sequences. Phylogenetic analysis showed that MsZEP was grouped into a branch with other legume plants. Real-time quantitative PCR revealed that MsZEP gene expression was clearly tissue-specific, and the expression levels were higher in green tissues (leaves and stems) than in roots. MsZEP expression decreased in shoots under drought, cold, heat and ABA treatment, while the expression levels in roots showed different trends. Besides, the results showed that nodules could up-regulate the MsZEP expression under non-stressful conditions and in the earlier stage of different abiotic stress. Heterologous expression of the MsZEP gene in N. tabacum could confer tolerance to drought and salt stress by affecting various physiological pathways, ABA levels and stress-responsive genes expression. Taken together, these results suggested that the MsZEP gene may be involved in alfalfa responses to different abiotic stresses and nodules, and could enhance drought and salt tolerance of transgenic tobacco by heterologous expression.

Molecular cloning and characterization of ClZE, a zeaxanthin epoxidase gene in watermelon (Citrullus lanatus)

“…Under chilling-low irradiance stress, the expression levels of ClZE gradually decreased after 3 h of treatment, then were reduced rapidly and reached the minimal levels after 12 h of treatment (Figure 4(B)). These expression levels of ClZE were consistent with those previously reported in alfalfa homologue [27]. However, some studies indicate that the expression of ZE genes is not induced by light and low temperature, but by diurnal rhythm, as those characterized in tomato [20], Nicotiana [28] and Arabidopsis [29].…”

“…Reduction of thermal dissipation in transgenic lines can lead to increase of the excitation pressure, and ultimately cause damage of the photosynthetic apparatus [20]. Since Fv/Fm represents the maximum potential of PSII quantum efficiency and is used as a parameter for measurement of the function of PSII reaction centres, the decrease in Fv/Fm mainly reflects the characteristics of photoinhibition [27].…”

A novel transcription factor-like gene SbSDR1 acts as a molecular switch and confers salt and osmotic endurance to transgenic tobacco

“…The SbpAPX gene confers salinity and drought tolerance to tobacco plants at different developmental stages5. Similarly, the overexpression of the novel gene(s) LcSAIN1, MsZEP and the TF, Zmhdz10 in plants leads to the improved tolerance to oxidative stress that is caused by drought and salt stresses161733.…”

“…Global transcript profiling has revealed that many genes are co-ordinately regulated by salt and drought stress1415. A novel MsZEP gene was cloned from alfalfa for functional validation by heterologous expression in tobacco, and the gene confers drought and salt tolerance in transgenic plants16. The overexpression of a novel Zmhdz10 in rice and Arabidopsis led to a significantly improved tolerance to oxidative stress caused by drought and salt stresses17.…”

Overexpression of a Plasma Membrane-Localized SbSRP-Like Protein Enhances Salinity and Osmotic Stress Tolerance in Transgenic Tobacco

“…However, it is challenging to identify key genes in the stress tolerance mechanism. A number of novel genes have been characterized, such as SbUSP, SbSDR1, MsZEP , and IbZFP1 , but other novel or uncharacterized genes may play a critical role in stress tolerance (Singh et al, 2016; Udawat et al, 2016; Wang et al, 2016; Zhang et al, 2016). The EST database contains about 30% novel or uncharacterized clone sequences for Salicornia .…”