Molecular Improvement Of Resistance To Clubroot Disease In Brassica Napus

Rapeseed is one of the most important oil crop in the world.Since the 40 years of reforming and opening up of China’s rapeseed industry structure policy implementation and to achieve four fold from low production to high yield and quality at the current time,raised the breeding goals towards,high oil content,high yield and high efficiency.However,clubroot is one of the most important soil borne disease worldwide and cause severe loss to rapeseed yield.The extensive farming of oil seed rape crop and trend toward agricultural mechanization,the clubroot disease spread the main Brassica growing areas in China,and cause outbreak that seriously affected the rapeseed industry.At present,breeding of resistance varieties to clubroot disease is considered to be the most economic and effective way to control and prevent disease.Therefore,the study was designed based on two resistance lines Bing409R(containing CRb gene)and Huashuang5R(containng Pb Ba8.1 gene)by backcrossing,selfing,molecular marker selection(MAS),field resistance identification test,and near infrared spectroscopy(NIR),and other techniques were used to develop a superior parents of Brassica napus.Two cytoplasmic male sterility types(Oug cms and Pol cms)and three recessive male sterility types(9012A)were used for the improvement of clubroot disease resistance.The following results were obtained in this study:1.A number of resistance and moderately resistance lines to clubroot disease were obtained from number of different backcross generation.Using MAS the resistance gene CRb was crossed with the B.napus HY1,HY2,W3 and Zhongshuang11 and backcross with their respective parents and a new homozygous disease resistance line was obtained in BCF5 generation.At the same time it was crossed with 8000 A,W1 and W2 separately and obtained a homozygous resistance line was obtained at BC3F2 generation.The line containing resistance gene Pb Ba8.1 were crossed and backcross with the W3,Zhongshuang 11,Bing409,Zheyou50,HS and LMT4 and a moderate resistance lines were obtained in the BC2F1 generation.2.Genetic improvement of resistance in cytoplasmic male sterile lines:Using two cytoplasmic male sterility types of cultivars,Polima and HY1,HY2,Bing409 and W3 genetic background,were used to introduced a disease resistance genes from from resistance source containing CRb gene of the same genetic background into a cytoplasmic sterile line,and successfully developed homozygous and disease resistance cytoplasmic male sterility lines that were capable to stable inheritance.3.Genetic improvement of resistance in the three recessive genic male sterile lines:The resistance genes(CRb)was introduced into the three recessive genetic male sterile lines with genetic background.The cultivars were HY1,HY2,13-5-1742,Zhongshuang11,Bing409,W2 and W3.No sterile plants were screened in BC4F2 generation.The above results aim to provide material support for the molecular breeding of rapeseed against clubroot disease and promote the sustainable development of the rapeseed industry.