Functional Verification Of Auxin-related Genes Induced By Dehydration Stress In Soybean

Soybean is important food and oil crop in China.It can be cultivated widely,which is easily affected by drought stress.Drought is one of the most serious abiotic stresses causing the decline of crop production.Improving drought tolerance of crops is an effective way to alleviate the shortage of water resources and ensure the stable development of agriculture.Auxin plays an important role in plant growth and development.In recent years,some studies indicated that overexpression or RNA silencing of auxin related genes in plants could improve the ability of plants to adapt to abiotic stresses.In this study,the digital gene expression profile(DEG),which contains different genes express level between drought-sensitive(Zhongdou 33)and drought-tolerent(Jindou 21)variety were obtained.The ten candidate IAA-related genes in Jindou 21 were chosen to analyse the function of abiotic stress by overexpressing those genes in Arabidopsis.Functional genes were further analyzed of gene expression,abiotic stress-tolerance physiological indexes,and protein subcellular location.1.Candidate genes had been cloned and overexpression plasmid vector were constructed and getted over-expression transgenic lines.The 15 k gene sequence of coding regions existed single nucleotide mutation by sequencing alignment between drought-tolerant and drought-sensitive variety.The coding sequence length of the 15 k gene was 1785 bp,different amino acid sites in 373(the position of Jindou 21 was serine,and proline in williams 82)the differential amino acid located in the domain of coenzyme A(Co A).2.Functional analysis of ten candidate genes had been completed.The results showed that overexpressing GmNAC8 could enhance drought-tolerance and salt-resistance of Arabidopsis.There were no difference between transgenic plants and WT of other candidate genes under salt or mannitol treatment.3.In further research,GmNAC8 contained the CDS full-length sequence(1092bp),encoded 363 amino acids.By bioinformatics analysis,The molecular mass and PI of GmNAC8 protein was 41.82 KD and 8.51 respectively,the aa residues in N-terminal of GmNAC8 contained a typical NAC conserved domain with 42 aa,and the aa residue in C-terminal was highly variable.The homology tree demonstrated that GmNAC8 shared high homology with Phaseolus vulgaris,Vigna angularis and Vigna radiata.Subcellular localization revealed that GmNAC8 located in the nucleus.The expression of GmNAC8 in leaf of transgenic lines was apparently higher than which in root by qRT-PCR.GmNAC8 was up-regulated under 0.1mmol/L IAA or ABA treatment,was down-regulated under 0.1mmol/L GA and SA treatment.The leaves of transgenic Arabidopsis were greener than WT,and drought tolerance was improved under water-deficit condion by overexpression of GmNAC8.The drought-tolerant physiological analysis revealed that the contents of protein,proline,and POD activity were higher in transgenic lines than WT under drought,while malonaldehyde(MDA)was significantly lower than WT.