Stress-resistance Study Of HD-Zip Gene Family Transcription Factor Zmhdz4 In Maize

Maize is one of the most important crops in the world.Environmental stresses,such as drought,salinity and high temperature can decrease the yield heavily.With the rapid development of genetic engineering breeding techniques,improving the crops tolerance under environmental stress by genetic engineering techniques and foster new crop varieties of strong resistance,has become a research hotspot in the genetic improvement of plant resistance breeding.Homeodomain-leucine zipper(HD-Zip)proteins are unique to plants in recent decades,studies have shown that HD-Zip involved in response to various environmental stress and plant growth.Our study selected a drought strongly indued gene of maize HD-Zip gene family,Zmhdz4,and through structure features analysis,Induced expression patterns and plant tissue expression pattern analysis,subcellular localization analysis,transcriptional activity analysis and overexpression of technology,we study the functions of Zmhdz4 gene in abiotic stress response.The main results are as follows:1.The gene has a typical HD and Zip domain by gene structure and sequence analysis,the two domains highly conserved and the Zip domain every 7 amino acids appeared a leucine residue,repeated six times.2.A drought strongly indued gene,Zmhdz4,was cloned from maize inbred line B73.Sequence analysis showed that the full-length cDNA of Zmhdz4 is 786 bp and encodes a protein of 261 amino acids.Induced expression patterns analysis showed that Zmhdz4 was also induced by salt stress and ABA;and tissue-specific expression indicated that Zmhdz4 was constitutively expressed in root,stem,leaf,tassel,filament,ear and cluster,but the highest expression was detected in leaf.3.Subcellular localization analysis showed Zmhdz4 protein is a nuclear protein localization.Yeast hybrid assays showed that Zmhdz4 can activate the expression of the reporter genes,and active area is located in the protein sequence of 1-54 amino acids.4.Zmhdz4 overexpression transgenic plants have no significant differences in the morphology compared with control plants.Overexpression of this gene can increase drought tolerance in transgenic plants by drought stress.Malondialdehyde relative electrolyte leakage and proline were tested in CK and transgenic plants.It indicated that transgenic plants had the lower membrane lipid peroxidationan and a lesser extent cell damage under drought stress.5.ABA sensitivity analysis of Zmhdz4 transgenic rice showed that transgenic rice of overexpression Zmhdz4 increased sensitivity to ABA,the root length and shoot height were suppressed more than CK plants in the same condition.In conclusion,we cloned Zmhdz4 from maize inbred line B73,and its molecular biological characteristics were also analyzed.The gene has a typical HD and Zip domain,induced expression pattern analysis revealed that the gene can be induced by drought,NaCl and exogenous ABA;tissue-specific expression indicated that Zmhdz4 was constitutively expressed in 7 tissues of maize,and the highest expression was detected in leaf;Zmhdz4 is a nuclear protein localization by subcellular localization analysis,and can activate the expression of the reporter genes,the active area is located 1-55 amino acids;overexpression of Zmhdz4 can enhance the tolerance to drought stress,which provides an excellent gene resource for improving crop resistance through genetic engineering method;ABA sensitivity analysis of Zmhdz4 transgenic rice showed increasing sensitivity to ABA.