RNA Sequencing Analysis And LRR-Ⅺ Subfamily Genes Identification Of Duli In Response To Valsa Pyri

Valsa canker caused by Valsa pyri(Vp),which is a major fungal disease in pear industry.Molecular breeding for disease resistance is regarded as a feasible way to control the disease,but the process is limited by the factors of the lack of depth research on disease resistance mechanism and the lack of resistance genes.Therefore,in this study,Duli(Pyrus betulifolia bunge)of resistant rootstock and ?Zaosu? and?Yuluxiang?(Pyrus bretschneideri Rehd.)of susceptible cultivars were used as materials.Using induction of callus,transcriptional sequencing,verification of gene functions and other technologies were to explore the resistance mechanism research system.The study showed the gene expression patterns of resistant rootstock and susceptible cultivars in response to Vp.It identified the members of receptor like kinase(RLK)subfamily LRR-Ⅺ,which can regulate resistance to Vp.The main results are as follows:1.The best culture medium for inducing and subculturing suspension cells of Duli and ?Yuluxiang? were obtained.The culture medium of Duli is NN69 + 6-BA 5 mg/L+ NAA 0.4 mg/L,and the culture medium of ?Yuluxiang? is MS + 2,4-D 0.5 mg/L +6-BA 0.5 mg/L.The interaction system of “Vp secondary metabolites-pear suspension cells” was established.And the best culture medium for Vp secondary metabolites is soluble starch(SS).The resistance of suspension cells of Duli and ?Yuluxiang? can be distinguished effectively after 10 days stationary cultivation.2.The gene expression patterns of one-year-old branches of Duli and ?Yuluxiang?in response to Vp signal are studied by transcriptome analysis.The results showed that ethylene(ET)and brassinolide(BR)related genes were up-regulated,and calcium dependent protein kinase(CDPK)and respiratory burst oxidase homologues(Rboh)related genes only in susceptible cultivar ?Zaosu? were expressed.Therefore,the expression patterns of DEGs associated with CDPK,Rboh,BR and ET were negatively correlated with the resistance to Vp,while the members of RLKs subfamily(such as LRR-Ⅺ)may play a positive regulation role in the response of pear to Vp.3.The gene expression patterns in response to Vp secondary metabolites(conidia suspension)in suspension cells of Duli and ?Yuluxiang? were is further analyzed.The results found that BR,ET,CDPK and Rboh related genes in ?Yuluxiang? cells were up-regulated,while the differentially expressed genes(DEGs)were down-regulated in Duli cells.Additionally,the expression of several members of RLK subfamily(LRR,Lys M and WAK)was significantly inhibited in ?Yuluxiang? cells,but not in Duli cells.These results indicated that CDPK,Rboh,BR,ET and LRR-Ⅺ play negative regulation roles in response to Vp.However,members of RLKs subfamily(LRR)play a positive regulation role in response to Vp.4.The members of LRR-Ⅺ subfamily were identified in genome-wide,189 and93 members in the genome of Duli and Baili have been found,respectively.They were divided into 8 subgroups.Cis-elements in the promoter region of Chr4.g40794.m2 and Chr3.g20593.m1 members of LRR-Ⅺ in Duli are related to defense and stress response.Further functional verification showed that LRR-Ⅺ-18 positively regulate the resistance to Vp.