The Heterologous Expression Of Maize PIN-1α And Its Function In Mycorrhiza

Maize is one of the important crops,its growth and development will be affected by various biological and abiotic stresses.Arbuscular mycorrhizal Fungi(AMF)is a symbiotic fungus that can form a symbiosis with the majority of vascular plants.AMF promote the absorption of external nutrients,so it help the plants improve the resistance.We found AM fungi promote the number of maize roots.It is speculated that AM fungi change the direction of endogenous hormones in maize roots,but it has not been confirmed.Auxin is one of the factors that lead to morphological changes of plant roots.Therefore,to explore the role of auxin transporter is helpful to clarify the importance of AM fungi.We found that the PIN family of maize have relationship with the mycorrhizal symbiotic signaling pathway.The ZmPIN1 a were identified by bioinformmatics.The function of ZmPIN1 a in mycorrhizal symbiosis were studied by overexpression and induction in plants.The main results of the study are as follows:1.ZmPIN1a and Os PIN1a have high similarity.ZmPIN1a protein have the typical N-terminal transmembrane domain,the intermediate transmembrane cytoplasmic region and the C-terminal variable domain.The result indicate the structure of PIN1 a in maize is similar to the structure of rice and sorghum.2.ZmPIN1α gene’s length is 1806 bp,and it can also encodes 411 amino acids.The molecular mass of the protein is 65.19 k D,and the isoelectric point is 8.90.By subcellular localization predictions,the result indicate that the protein of ZmPIN1 a is localized in the cytomembrane.Heat map expression analysis predicted that ZmPIN1 a is highly expressed in roots.We identified the AMF element from ZmPIN1 a promoter by bioinformmatics.The result indicate ZmPIN1α is associated with mycorrhizal symbiosis.3.Comparing the GUS staining,it was found that the roots of mycorrhizal symbiosis had the phenomenon of lateral root staining.the result indicate AM fungi regulate the expression of ZmPIN1 a in lateral roots.Comparing the symbiotic with AM fungi,it was found that ZmPIN1 a promote the number of lateral root in mycorrhizal symbiosis.Comparing the result of the colonization,it was found that ZmPIN1 a inhibited reproduction of spores.the result indicate the overexpression of ZmPIN1α increased the auxin concentration in roots,while inhibite mycorrhizal symbiosis.There was no difference in the expression of ZmPIN1 a before and after AM fungal infection.4.The results showed that the overexpression of ZmPIN1α in root system significantly decreased the content of IAA,IPA,NAA,ABA and GA3,while the content of ZT was basically unchanged and the content of IBA was significantly increased.The content of IAA,IPA,ZT,GA3 and ABA increased significantly in mycorrhizal symbiosis.The result indicate the content of IAA in the root was changed by ZmPIN1 a.The decrease of IAA content inhibit mycorrhizal symbiosis,thus it affected the content of other hormones.