Characterization Of Maize Actin Depolymerizing Factor 5 During Drought Stress

Maize (Zea mays L.) is an important cereal crop for food, forage, oil, and raw material for the production of energy. The demand for maize is on the increase each year, as the development of population and industry. Drought is the major abiotic factors for the maize production reduction. Drought resistant gene discovery has contribute to new drought tolerance cultivars. Actin depolymerizing factor (ADF), a kind of actin binding protein, plays an important role in plant’s growth and adaptation to biological and abiotic stresses. According to the linkage analysis and association analysis, a drought tolerance candidate gene GRMZM2G077942 was found on bin 1.03, which encode ADF5 protein. Candidate gene association analysis and transgene technology were used to study its function, the main result were as follows:(1) Grain yield that had been evaluated in eight environment in 188 maize inbred lines were analyzed in combination to study their association with 41,101 SNPs. A total of 64 significant association sites were detected withp≤5×10-4, which were corresponding 41 annotated genes. Among the SNPs,11 SNPs were detected under water-stress condition, and PZE-101047611 maker has the highest R211.61%, which is located in the 5’-UTR of gene GRMZM2G077942. PZE-110051815 and PZE-110051809 are located in the exon of gene GRMZM2G386956, which annotated as leucine-rich repeat, a kind of transposable elements possibly. PZE-110052198, PZA00048.2, PZA00048.1 were located in the intron and 3’-UTR of gene GRMZM2G007721, respectively, which encodes a glycosyl transferase, family 28. Gene GRMZM2G077942 is located in the most possible site of a consensus QTL detected by meta-analysis, and was thought to be a drought tolerance candidate gene.(2) Nucleotide sequence analysis of ADF gene in maize and seven related plants showed that ADF5 and ADF9 were in the same evolutionary branches. The consistency of ADF5 nucleotide sequence in rice, maize, millet, potato and wheat was high, and may have a similar function. The subcellular localization analysis shows ZmADFS protein expresses in cytoplasm.(3) Candidate gene association analysis of ADF 5 in 137 maize inbred lines and their grain yield under WW and WS conditions showed eight polymorphic sites were significant associated (p< 0.05) in varied environment. Relative higher LD (r2> 0.8) were identified between site-206,-42 and 77. Site 422,468, 582 and 707 have high LD (r2> 0.9). Site-206 has a high marker R2 of grain yield under WS condition, which accord with the GWAS result. The 137 maize inbred lines were divided into three main haplotypes. Among them, haplotype 2 which contains Qi319 inbred line, has the lowest production losses, and was thought to be the drought tolerant haplotype in ZmADF5.(4) qRT-PCR analysis revealed that the ZmADF5 transcripts were induced by drought, ABA and cold stress. The overexpression of ZmADF5 in the transgenic Arabidopsis enhanced drought stress tolerance. The result might be ZmADF5 stimulated the growth of roots and shorten the growth stage during the drought stress.