Study On The Function Of Apple MdMYB108L Gene In Plant Salt Stress Tolerance

Plants are affected by various abiotic stresses during growth and development,such as drought,salt stress,and low-and high-temperature.When plants are subjected to abiotic stresses,they exhibit a series of responses,including some transcription factors being activated and changing the expression of downstream genes to improve resistance and enhance the plant’s adaptability to the environment.Studies have found that MYB transcription factors play an important role in the process of plant response to adversity stress.At present,MYB family has been extensively studied in a variety of plant adversity stresses.Apples have been favored by the public for many years,but in recent years,environmental changes such as soil salinization have seriously affected the growth and yield of apples.Therefore,the function of MYB in apples has been deeply explored,and genetic engineering technology has been used to improve its resistance,which is useful for guiding agriculture.Production has important practical significance.In this study,the MdMYB108L gene was cloned from apple,the overexpression vector was successfully constructed,and transgenic Arabidopsis thaliana and MdMYB108L overexpressing apple hairy roots were obtained.The specific results are as follows:(1)Full-length cDNA of apple MdMYB108L(MDP0000823458)was obtained.The gene has a length of 873 bp,encodes 290 amino acids,has a protein molecular weight of 32.9 k Da,and an isoelectric point of 4.91.Comparison of the amino acid sequence of MdMYB108L revealed that has the R2R3 functional domain.(2)Results from tissue expression analysis showed that the expression of MdMYB108L was highest in leaves and that the gene was induced by salt stress,ETH and IAA.Activation of transcription indicated that the transcription factor MdMYB108L had transcriptional activity at the N-terminus.(3)Transgenic and wild-type Arabidopsis plants were exposed to different concentrations of NaCl.The results suggested that the germination rate and main root length of the transgenic Arabidopsis plants were significantly higher than those of the wild-type.The transgenic Arabidopsis contained more osmo protectant,such as proline and soluble sugars,compared to the wild-type after 200 m M NaCl treatment for 7 d.The electrolyte leakage and MDA content of transgenic Arabidopsis were significantly lower than that of wild-type Arabidopsis,which indicated that the membrane system of transgenic Arabidopsis was less damaged.Also,under salt stress conditions,the antioxidant enzyme activity of CAT and POD of transgenic Arabidopsis was significantly higher than that of the wild type,and the accumulation of active oxygen was significantly lower than that of the wild type.The results of the maximal photochemistry efficiency of PSII and total chlorophyll content of the transgenic apple hairy roots(leaf)showed that the damage suffered of photosynthetic capacity of hairy roots overexpressing the MdMYB108L gene was significantly lower than that of the wild type after salt stress.(4)When exposed to salt stress,with the increase in NaCl concentration,the relative expression levels of MdNHX1 and Md HKT1 were significantly up-regulated.At the same time,the expression levels of MdMYB108L and MdNHX1 were consistent.Expression analysis using pericarp-transient injection showed that MdMYB108L and MdNHX1 gene expression was positively correlated.A firefly luciferase experiment indicated that the transcription factor MdMYB108L could activate the transcription of MdNHX1.A yeast one-hybrid experiment revealed that MdMYB108L could bind to the promoter of the MdNHX1 gene in vitro.Therefore,we inferred that MdMYB108L could positively regulate the transcription of MdNHX1 to improve the salt tolerance of transgenic plants.