Cloning And Expression Analysis Of Powdery Mildew Resistance Associated Genes HbGNOM And HbFER In Hevea Brasiliensis

Rubber tree(Hevea brasiliensis)is the main source of natural rubber and natural rubber occupies an important position in the national economy.Powdery mildew is the most serious leaf diseases of rubber tree and cause yield losses.In the previous study,we analyzed the gene differential expression of rubber tree inoculated with powdery mildew by RNA-Seq.Two unigenes(numbered as CL13480 and CL406)showed expression difference significantly and named as HbGNOM and HbFER respectively.In this study,HbGNOM and HbFER were cloned and the function of HbGNOM and HbFER were analyzed.The detailed results were as follows:1.The ORF of HbGNOM contains 4410 bp and encodes a peptide with 1470 amino acids.Bioinformatics assay showed that HbGNOM protein contained a Sec7 conserved domain,which was similar to the GNOM proteins of Jatropha curcas,Manihot esculenta,Ricinus communis and Arabidopsis thaliana,and the similarities were 97%,96%,95%and 84%,respectively.Semi-quantitative analysis showed that the expression of HbGNOM gene was induced by ethylene(ET),but there was no obvious change to the treatment of salicylic acid(SA),jasmonic acid(JA),gibberellin(GA)and Abscisic acid(ABA).The expression level of HbGNOM gene was significantly increased in leaves infected with powdery mildew,but no change in the leaves infected with Colletotrichum gloeosporioides.The results above suggested that HbGNOM may participate in the resistance of rubber tree to powdery mildew and be related to ethylene signal transduction pathway.Subcellular localization result indicated that HbGNOM protein was located on the cell membrane and endoplasmic reticulum.2.In Previous study,the gene encoding FERONIA receptor kinase of rubber tree,HbFER,was cloned.The bioinformatics analysis showed that the full length of HbFER was 2679bp encoding an 892 amino acid polypeptide with Malectin-like and PTKc conserved domains.PAMPs molecular flagellin(flg22)and chitin could inhibit the expression of HbFER gene.In this study,the expression pattern of HbFER was detected.The results showed that the expression of HbFER gene in rubber leaves could be induced by the infection of powdery mildew,but not C.gloeosporioides.Salicylic acid(SA),gibberellin(GA)can induce HbFER gene expression,while Jasmonic acid(JA),ethylene(ET),Abscisic acid(ABA)had no significant effect on the expression of HbFER gene.The subcellular localization study showed that the HbFER was located on the cell membrane.The data above indicated that HbFER was involved in the resistance of rubber tree to Odium Heveae steinm and associated with SA and GA-mediated signal transduction pathways.