Relations Of Genetic Distance And Heterosis In Sweet Maize By SSR Marker

Exploring the feasibility of using molecular methods predicting heterosis,auxiliarily improve sweet corn inbred lines and equipping hybrid combinations to reduce blindness breeding.In this paper,the tested materials are 13 sweet corn inbred lines with big phenotypic difference and compunding 42 types of hybridized combinations according to the NC incompleted diallel cross design.We use the inbred lines and ?the test data of final generation of F1 to do the advantage analysis of the 14 characters.Using SSR molecular marker to do the genetic distance analysis of 13 selected materials,and divide the sweet corn inbred lines into heterosis groups,analyze and research the relationship between genetic distance marked by SSR and heterosis.Following are the results :(1)The analysis of variance and heterosis: we do the variance analysis with 14 characters of 42 hybrid combinations,and got a significant difference among various combinations.It shows that real genetic differences exist in different traits;The F1 generation of various characters are superior to the average of the parental inbred lines;Heterosis analysis result shows that both average heterosis and heterobeltiosis have big amplitude of variation.On the whole,both average heterosis and heterobeltiosis have more positive advantages than the negative;Following are the comninations of superiority in this test: A1×B5?A2×B1?A4×B2?A4×B3?A5×B2?A5×B3?A7×B4.(2)The analysis between genetic distance of SSR marker and cluster : the genetic distance of SSR markers in inbred lines is btween 0.1111-0.9118,average distance is 0.7133.The biggist genetic distance is 0.9118 which is between A6 and B6 and the smallest distance is only 0.1111 which is between A7 and B6.We analyze the cluster by using UPGMA,and take the genetic distance 0.72 as a standard,these 13 sweet corn inbred lines can be divided into four categories.The first category is divided into two subsets including five sweet maize inbred lines,1 subsets including A1,B4,B5,2 subsets including B1,B2;second class is divided into two subsets including three sweet maize inbred lines.1 subsets including A2,B3,2 subsets including A5;third class is A4 and A6 two sweet corn inbred lines;fourth class is divided into two subsets including three sweet maize inbred lines.1 subsets including A3,A7,2 subsets including B6;(3)The relationship btween genetic distance and heterosis : the genetic distance and the various characters of heterosis index does not exist significant correlation in these 42 hybrid combinations;the correlation coefficients of top five genetic distance in parental inbred lines to plant height,stem diameter,ear length heterosis are 0.9246,0.9507,0.9178.We come to the conclusion based on the test method and test material: The close genetic relationship of sweet corn's plant height,stem diameter and ear length can be predicted by genetic distance.That is,only in sweet corn inbred lines close genetic relationship,the greater genetic distance,the greater the plant height,stem diameter and ear length character of heterosis index.