| Castanea henryi is a unique woody tree species in China.There is a long history of C.henryi cultivation in Jianou City,Fujian Province where formed a batch of native variety with sound phenotype through continuous natural selection and artificial selection.The occurrence of Chestnut blight seriously affects the yield and quality of C.henryi while breeding new varieties with high resistance is prior to prevent and cure Chestnut blight.Taking 17varieties of C.henryi native varieties planted in Jianou City as material,this paper established a method to detect the resistance of the chestnut blight,analyzed the variation of resistance and important economic traits of the native varieties,carried out artificial crossing,studied the variation of the resistance and important economic traits for the offsprings,and established a genetic mapping population.The results are of great significance for understanding the genetic mechanism of resistance to the disease.It lays a foundation for breeding resistant varieties in combination of the methods of traditional and molecular breeding.The main findings are as follows:1.The pathogenic bacteria was isolated from the infected tissues of C.henryi native varieties from Shuiyuan Township of Jianou City.According to the morphological observation and the DNA sequencing,it can be determined that the pathogenic bacteria is Cryphonectria parasitica.By testing the resistance of"Chushuhong"and"Youzhen",it was determined that the 21d after inoculation was suitable for evaluating the resistance of Chestnut blight.2.Variation analysis was made on the resistance and important economic traits of the native varieties.The incidence index of Chestnut blight in the 17 native varieties were 23.55?59.00.Among them,"Xiaojianzui"owned the highest resistance,and"Chushuhong"was most susceptible.The disease resistance types of the tested native varieties were divided into 4 categories.For 24 phenotypic traits,the coefficient of variation were between 7.78%?49.65%,and the mean coefficient of variation was 21.79%.Among them,the coefficient of variation of soluble protein was the lowest while the coefficient of variation of nuts weight was the highest.There were significant differences?P?0.05?in the number of leaf veins among native varieties.Meanwhile,there were highly significant differences?P?0.01?in the incidence of Chestnut blight and 17 other traits.With standardized ranking of 24 phenotypic traits,"Chushuhong","Wuzhen"and"Huangzhen"ranked at the top three.Through cluster analysis,17 native varieties are divided into 4 categories.3.Five native varieties were used for diallel crossing to obtain15 combinations.There were some variations among the traits of the fruit.The coefficient of variation is between 9.25%?35.87%for each trait,with the mean of 18.19%.The coefficient of variation of nuts shape index is the lowest,and nut weight is the highest.4.We analyzed the resistance and seedling traits of the filial generation.The chestnut blight index ranged from 20 to 45 in 27families with an average of 30.77;JO4×JO1 and JO6×JO12 had the highest disease resistance,and their infection index was 20,while the most susceptible family was the JO12×JO6,with infection index of45.The coefficient of variation of each trait was between15.18?29.41%,and the average coefficient of variation was 21.08%.There were significant differences?P?0.01?in infection rate,seedling height,leaf length,leaf aspect ratio,petiole length and leaf area of the families.We aslo selected the excellent families and individuals.5.Variation analysis of resistance and seedling traits of four large F1families was carried out,showing that JO6×JO12 had higher coefficient of variation in infectious disease rate?19.43%?and mean coefficient of variation?25.54%?of traits in seedling stage.Combining with the molecular marker genetic distance of the parents,the JO6×JO12 family was determined as the mapping population to construct the genetic linkage map of the C.henryi. |
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