Rice Blast Improvement Of Changnongjing 1 By Using Molecular Marker-assisted Selection

Rice disease is considered to be a disease caused by rice blast that occurs all over the world.Breeding resistant rice varieties is the most economical,effective and environmentally friendly control measure.In recent years,a number of rice blast resistance genes have been identified and cloned,and breeders have begun to introduce these blast resistance genes into existing rice varieties by molecular breeding methods,and many new rice varieties with resistance to disease have been developed.In this study,the resistance gene Pi2 in C101A51 was introduced into rice variety Changnongjing 1 by using continuous backcross technology and DNA marker-assisted selection technology.The improved line Changnongjing 1 was planted in the field to identify blast resistance,select the main agronomic measures,evaluate the yield and quality traits comprehensively,and screen out a new improved line for disease resistance and high yield.The main results of our study are as follows:1.The molecular marker PI31 was screened out to have different genotypes between recipient parents and donor parents,and the selected markers could be used to identify the resistance genotypes of Changnongjing 1,C101A51 and their progeny.2.Cross Changnongjing 1 with C101A51 as the female parent,identify the true hybrid with PI31,and backcross the true hybrid with Changnongjing 1.The BC₁F₁generation population was planted,and the single plant carrying Pi2 was identified by PI31.The BC₂F₁ generation population was obtained by further backcrossing with Changnongjing 1 based on the selection of agronomic traits.The excellent lines carrying Pi2 were identified by PI31 and self-crossing was cultivated to obtain BC₂F₂.PI31 was used for genotype identification,yield performance and stability identification of lines.A stable and excellent line with agronomic traits was selected,which is the improved line of Changnongjing 1,and the improved line of Changnongjing 1 was further studied.3.Identification of natural induced rice blast resistance of the improved Line Changnongjing 1 at the rice blast identification point of Wangjia Village,Lei Zu Town,Yuan’an County,Yichang city,Hubei Province.The identification results showed that the improved line Changnongjing 1 was susceptible to blast,while Changnongjing 1was highly susceptible to blast.The resistance of the improved line to blast was significantly better than that of Changnongjing 1.4.The main agronomic traits of the improved strains of Changnongjing 1 were investigated.The results showed that the growth period of changnongjing 1 improved line was significantly shortened,and several yield-related traits of the improved line were significantly different from those of Changnongjing 1.5.The quality traits of the improved strains of Changnongjing 1 obtained were investigated.The results showed that there were significant differences in some quality traits between the improved line changnongjing 1 and changnongjing 1.The chalkiness degree of the improved strains was higher and the quality decreased.