Effect And Mechanism Of MdNAC29 In Apple To Salt And Drought Stress

The apple(Malus pumila Mill.)is a deciduous tree.It is a perennial fruit tree of the family Rosaceae.It is also one of the most widely cultivated fruit tree species in the world.Apple trees encounter various biological and abiotic stress effects during their growth and development.Among them,there will be significant water loss under drought stress,resulting in water balance and nutritional disorders,resulting in decreased transport and distribution of nutrients,which in turn leads to slower plant growth and lower fruit yields.In the process of plant adaptation to the environment and defense against stress,the transcriptional expression of related stress genes plays an important role.At the same time,the expression of these genes is inseparable from the effective regulation of various transcription factors in plants.The NAC family is one of the transcription factors that play an important role in it.It exists in higher plants and has a variety of biological functions.This study uses the NAC29 transcription factor in apples as the research object to explore the role and mechanisms of plants in dealing with drought and salt stress.1.The MdNAC29 was cloned from leaves of apple 'GL-3' plantlets.The coding region of the gene was 840 bp in length and encoded 279 amino acids.The sequence of the gene was found to contain a highly conserved DNA NAC.The binding domain is similar to the Arabidopsis AtNAP up to 58%.2.Analysis of the cis-acting elements on the MdNAC29 transcription factor promoter sequence revealed the presence of cis-acting element binding sites such as ARF,DRE,and ABRE.The presence of these functional elements explains the hormonal induction of MdNAC29 expression;Subcellular localization experiments showed that MdNAC29 is located on the nucleus.3.Construct the overexpression vector pRI-MdNAC29,transform the leaves of apple 'GL-3' tissue-cultured seedlings by Agrobacterium-mediated method,then three transgenic lines were obtained.After the treatment of dehydration and salt stress,the results showed that MdNAC29 negatively regulate the plant on salt and drought stress.The qRT-PCR analysis of the expression of key genes of drought and salt stress showed that the expression of these genes were down-regulated.The MdDREB2 A gene was subjected to EMSA.The results showed that the MdNAC29 transcription factor can directly bind MdDREB2 A promoter.It was shown that MdNAC29 negatively regulates drought and salt stress responses in plants by binding to an anhydrate response gene promoter and inhibiting its expression.