The Sensitivity Identification And Polymorphism Analysis Of Cotton Induced By Space Mutation

To study the sensitivity of different varieties of cotton induced by space mutation and the stability of sensitive varieties ,ten cotton varieties ,including 5 spring cottons and 5 shorted-season cottons, were carried by the Shijian-8 satellite for space mutation treatment. The plant height, fruit branch number, boll number, mutation rate were investigated with the field investigation, the seed cotton, lint, boll weight, lint percentage were collected by doing statistics, and fiber quality were detected. Through the comprehensive analysis of different types of cotton materials after space mutation, this article preliminary studied on the mechanism of cotton space mutation. The main results were as follows:(1) Screening mutants. The SP₁, SP₂, and SP₃ offspring of Cotton Varieties after space mutation were used to screen mutants. The result is: 1) the changes which were not genetically transmissible to offspring were mostly from the seedling stage, for example monocotyledon, three cotyledons and so on .2) the changes which are genetically transmissible to offspring include Zhong 502181 which had a yellow spot in the center of the cotyledon, and Zhong 50191 from which the dwarf and shortened life period individual plant had been screened.(2) Different varieties of cotton showed various degrees of sensitivity to space mutation. Zhong A3025, Zhong A3023 changed obviously on the morphological traits and yield traits, while Zhong502181, and Zhong 04002 on the yield traits and fiber quality traits. However, Zhong30041 changed on the fiber quality traits obviously after space mutation.The results of simple correlation, path analysis on lint percentage and other ten traits of upland cotton showed that the correlation of length (upper half mean), elongation and the strength with lint percentage than the other were more stable. There were four phenomenons: 1) the correlation was conspicuous and stable, such as upper half mean; 2) the CK was conspicuous but the offspring were not, such as uniformity index; 3) the correlation of SP₂ and SP₃ were conspicuous and stable but CK and SP₁ were not, such as seed cotton; 4) the correlation of SP₁ and SP₂ were conspicuous and stable but CK and SP3 were not, such as plant height. The canonical correlation analyses of morphological traits, yield traits and fiber quality traits also had changed after space mutation treatment.The results of simple correlation, path analysis on lint percentage and other ten traits of Sea Island cotton showed that the correlation of lint and stretching rate with lint percentage were very significant; the direct path coefficient of seed cotton and lint with lint percentage were the largest. From the canonical correlation analyses, the Correlation coefficient of morphological traits and yield traits after space mutation were not stable as well as morphological traits fiber quality traits. Just like the CK, the plant height in the SP₁ and SP₂ of morphological traits was the most important; the correlation coefficient of the yield traits and fiber quality traits was very complex.(3) Analyze the DNA Molecular Polymorphism of the varieties of cotton after space mutation, we found that gene variable sites showed more, less and long amplified fragments. There were three phenomenons: 1) high polymorphism and stable; 2) high polymorphism in SP₁ but not in SP₂; 3) high polymorphism in offspring except in SP₁(4) The correlation of the variation traits and SSR sites. Combining the data analysis with marker analysis, there were some correlation between them: 1) the variation of the agronomic traits guided the marker analysis. To get the corresponding polymorphism, the marker analysis were pointed made for the materials which had obvious variation with CK on the field traits ;2)the high polymorphism results guided the materials with high agronomic traits variation. Through the molecular markers detection, materials with high polymorphism were analysised on the traits data, and found corresponding variated traits.