The Function Studies Of Phytosulfokine Receptor PePSKR Of Disease Resistancein In Populus Tomentosa

Poplar canker(Botryosphaeria ribis),an important stem disease of poplar,has become one of the most important forest diseases in China.As an important economic tree species in China,Chinese white poplar plays an important role in ecological value and economic value.Phytosulfoneptide receptor(PSKR)belongs to the family of receptor kinases(LRR-RKs),one of which has an extracellular leucine repeating sequence and four relatively conserved domains located in the intracellular segment,namely ATP binding site,CAM binding site,kinase active site and guanosine cyclase center.PSKR is involved in regulating the growth and elongation of plant roots and the immune process of plant resistance to disease and insect pests through the cooperation of PSKR and phytosulfoneptide(PSK).The PePSKR gene of Populus euphratia was cloned in this study.Then,the overexpression vector and interference vector were constructed to transform Populus tomentosa.The function of PePSKR gene was studied by treating transgenic Populus tomentosa with poplar canker disease.Subcellular localization vectors were constructed and transformed into rice protoplasts to determine the subcellular localization of PePSKR protein.To construct promoter vector and transform Populus tomentosa to study the tissue specificity of gene.The research results are as follows:1.Fluorescence quantitative analysis and GUS staining indicated that PePSKR was mainly expressed in the stems and old leaves of Populus tomentosa.The exogenous hormone induced expression of P.tomentosa PSKR1 in leaves was detected can be induced by SA and ETH,and its expression can be inhibited by JA.Promoter response element and PSKR1 of Populus tomentosa;The expression of PePSKR in leaves,roots and stems of Populus tomentosa could be induced by SA,IAA and ETH through hormone induction analysis.Me JA can induce the expression of PESKR in roots,stems and petioles.2.Through the subcellular localization experiment,it was found that PePSKR was localized on the cell membrane.A large amount of lignin was accumulated in the stem of transgenic Populus tomentosa by slice observation and lignin biosynthesis related gene expression analysis.After transgenic Populus tomentosa leaves were inoculated with poplar ulcer pathogen,the results showed that the wild-type plants showed a large number of lesions,while the overexpressed plants showed only sporadic lesions.Through the analysis of the infected area of leaves,the infection degree of the overexpressed plants was significantly lower than that of the wild type.Meanwhile,by measuring the content of calcium ions and ROS in leaves,it was found that compared with the wild type,the content of calcium ions in the leaves of the overexpressed plants increased while the ROS content did not significantly change.In conclusion,PePSKR1;1 can promote the increase of stem lignin content through IAA.PePSKR1;1 gene also can participate in the SA、ET and IAA signaling pathway,and improve the ability of Chinese white poplar to deal with ulcer disease by increasing the content of calcium ions.