Cloning And Analysis Of Sheath Blight Resistance Related Gene Analogs In Maize

Maize banded leaf and sheath blight(BLSB),caused by Rhizoctonia solani Kühn,is a destructive disease that results in significant yield loss in most maize-growing areas in China.Although this is a regional maize disease mainly occurring in China and Southeastern Asia,it is possible that this disease may spread to other parts of the world in the future.To breed new varieties with efficient,broad-spectrum,stable resistance to the maize BLSB,the understanding of resistance mechanism is of great importance.In this research,resistant sheath blight material "R15,Mol17Ht,Chang 7-2," and the infect material "ye-478" genomic DNA as the templates.According to the amino acid conservative regions of the known resistance gene structure to design primers.Use PCR method to cloned and sequenced the resistance gene homology sequence(RGAs)with resistant materials,the findings were the following:1.Used materials "R15,Mol17Ht,Chang 7-2," and "ye-478" genomic DNA as the templates,according to the conservative regional of R gene to design primers for PCR amplification,we found 24 special amplificated fragments,which were about 500 bp, between two type materials.2.Cloned,sequenced and analysised the difference fragments,the results showed that eight cloned fragments had conservative structure of R gene.Deduced and analysised amino acid sequence of the eight RGAs showed that:This eight RGAs can be divided into three categories.They were LZ-NBS-LRR,Pkinase and TIR-NBS-LRR.3.Submitted the eight difference sequences to Genbank in a Blast comparison,we got that five sequences were known function of the gene,three sequences were newly discovered.Classificated the known gene function,we found:these genes involved in disease resistance or defensive pathways,signal transduction,transcription regulation, secondary metabolites,the primary metabolism,protein metabolism,and other one related to cell structure.4.Submitted the eight difference sequences to MaizeGDB in a Blast comparison,we found that eight sequences major located in the 1,4,6,9 chromosome of maize.Used the methods of bioinformation and comparative genomicsa,the five known sequences mainly located in the maize chromosome 1,4,6,9,and got the linkage molecular markers.And our interest was EST sequence of the Y1 gene was in the maize chromosome 6.01-point,and its neighboring markers were umc1083 and bnlg1538.The marker also linkaged with the maize sheath blight resistance QTL qBLSB6aY,which located by the population of R15 as the resistance parent.5.Comprehensive analysised the functional genes,we can arised the resistance mechanisms after the sheath blight infection on maize,and simulated the regulation model of metabolic pathway and signal transduction in the resistance way.This mechanism model was the foundation of the further resaerch in cloning resistance gene and sheath blight resistance tansgene.