Genetic Analysis Of Special Corn Inbredlines To S.reilianum And Genetic Diversity Of S.reilianum

Based on the resistance identification of inbred lines of common corn , popcorn , waxy corn and sweet corn to S. reilianum, RAPD markers were used for genetic diversity analysis of resistance of common corn inbred lines ; The inheritance of resistance of popcorn and waxycorn to S. reiliancum were studied with Griffing method 1 in complete diallel cross; The pathogenic differentiation and genetic diversity of S. reilianum from different regions in jilin province were studied with a combine method of differential hosts and RAPD markers.The results as follows:a) Three hundred and sixty-five inbred lines including all of kinds of corn were evaluated for reaction to S. reilianum with artificial inoculation, the results showed that 127 lines(US3195 etc.) were resistant to S. reilinum. Most of special corn lines tested were susceptible or high susceptible, no high resistant or immune lines. The cluster analysis by RAPD markers showed that thirty-three common corn inbred lines could be classified into five distinct groups, the results were not completely consistent with the expected grouping based on available pedigree, but consistent with that of heterosis utilize, no excellent crosses were found in the same group, thirteen resistant inbred lines were found in five groups, respectively. According to program of heterosis utilize, resistant inbred lines could be used to improve non-resistant inbred lines for new resistance lines to S. reilianum.b) The inheritance of resistance to S. reilianum was studied from five popcorn crosses and seven waxycorn crosses, the results showed that the inheritance of resistance of popcorn and waxycorn to S. reilianum was nuclear inheritance, the disease incidence of F₁ was between the resistant and susceptible parents, and approached to the average of parents, and there was not significance in reciprocal cross, and was closely correlated with that of parents. Resistance of F₂ is higher than that of F₁, resistance of BC was up to resistance level of parents, the g.c.a and s.c.a were different among different lines. Additive and dominant gene effects as well as gene interaction could be found in the inheritance of resistance to S. reilianum, and gene effects were variable in different crosses, but gene additive effect was dominant.c) Through a great number of field investigations and inoculation identifications repeatly, eight common corn inbred lines (He344, B73, Ye478, 444, J1853, Mo 17, Huang zao4, P138)which represent different resistant and susceptible level of corn inbred lines to S. reilianum and main consanguinity widely used in China corn breeding were selected as ideal differential hosts for pathogenic differentiation of S. reilianum.d) Nine pathogen collections of 5. reilianum were inoculated on eight differential hosts in field, respectively. The results showed that the nine pathogen collections were divided into three pathogenic types in which they were type A with high pathogenicity, type B with moderate pathogenicity and type C with weak pathogenicity. Type A were originated in most important corn grown areas including Changchun, Jilin, Gong Zhuling and Changling county where corn head smut usually occurs severely, type B were collected from Siping, Tonghua, Songyuan, Yanbian and type C were collected from Baicheng where disease usually occurs very lightly. The results also showed that the pathogens of S. reilianum in Jilin province were only different in pathogencity, no special interactions between cultivars and pathogens.e) Twenty-one isolates from different regions in Jilin province were classified three groups based on RAPD markers. Group A including S03-22,S03-6,S02-4,S02-5 , S03-10,S03-3 from Changchun, Jilin, Gongzhuling; Group B including S03-13, S03-7, S03-19, S03-24, S03-11, S03-16 from Siping, Tonghua and group C including S03-23, S03-8, S03-15, S03-9, S03-19, S03-18, S03-1, S03-20, S03-21 from Baicheng, Yanbian, Songyuan. The similarity of between groups was 33.33 percent, but in the same group the similarity between isolates reached to 100 percent. The results further indicated that diversity of DNA of pathogens was related to their source, no relationship with cultivars.f) The results by differential hosts were closely correlated with that of RAPD analysis, especially in the pathogenic collections with high virulence, this further revealed that pathogenic differentiation of S. reilianum were due to the difference of their DNA.g) Method of differential hosts combined with RAPD analysis to study pathogenic differentiation of S. reilianum was the first time in the world.