Location Of Wrinkled Leaf Mutant Gene Wr₃

Cotton is the world’s most important fiber crop, and it is a necessary natural raw materials for China’s textile industry.Wrinkled leaf mutant is easy to be distinguished, and the phenotype of this mutant is stability, so it has an important role in the construction of mutant libraries and the classical genetics gene mapping.There were many reports about wrinkled leaf mutant found in cotton abroad and domestic. But the localizations of the wrinkled leaf mutant gene were analyzed with classical genetics, and there had no mutant gene located on a chromosome because of the rare numbers of morphological markers at present.In this study, a new wrinkled leaf mutant discovered by our project in Upland Cotton groups independently was used as the experimental material. The early genetic analyses found that the phenotype of our mutant was different from the analogous mutant reported by the predecessor. The mode of inheritance was fully comply with Mendel’s regulavity of segregation, and it was a qualitative trait controlled by a pair of recessive gene. We got F2 segregation populations from intraspecific crosses with wrinkled leaf mutant L037 and Hai7124. We identified the polymorohic bcis with SSR primers by screened in parents, then using these locis analyze the F2 segregation populations and part molecular linkage map was constructed. The wrj gene was located finally from the perspective of molecular genetics. The results were listed as the following:1. Study of the phenotype and segregation law of F2 mapping populationsIn the study, the normal leaf Island Cotton "Hai 7124 " was female, the wrinkled leaf mutant L037 was male. We got F1 and F2 from the intraspecific crosses. The phenotypic traits about the 150 bodies were counted during the early flowering in which wrinkled leaf traits were expressed clearly. The results showed that the number of wrinkled leaf plants(43) to normal leaf ones(107) in F2 population was consistent with 3tol separation ratio (χ2=0.334<χ20.05,1=3.84). This results verified that the wrinkled leaf mutation was a qualitative trait controlled by a pair of recessive gene with the F2 segregation populations crossed with upland cotton and island cotton.2. Construction of genetic linkage groupIn total,240 pairs of SSR primers were used to screen the polymorphism between L037and Hai7124. Total 123 polymorphic loci were produced, accounting for 51.04% of the total loci.134 polymorphic loci were used to construct the molecular linkage groups by Joinmap 4.0. A map with 95 loci and 23 groups was obtained. The map covered 631.3 cM with an average intermarker distance of 6.79 cM, accounting for about 17.17% of the whole tetraploid cotton genome. The length of each linked group was between 1.1cM to 108.2 cM. And the average length was 27.44cM with 4.04 loci per group. All linkage groups were assigned to 22 chromosomes of tetraploid cotton except A10 (Chr10)、All (Chr11)、 D10 (Chr20)、D13 (Chrl8).3. Location of wrinkled leaf mutant gene wr3234 pairs of core primer covered 26 pairs of chromosomes in cotton were used to screene differential marker by the method of BSA, and 12 polymorphic primers were obtained. After the detection of each plant’s genotype about F2 population, BNL3279 were found to link to target gene wr3 with the distance of 28.7 cM. According to the known genetic map, BNL3279 belonged to chromosome 21. Then we screened all other primers on chromosome 21, and found that 16 pairs of primers could link with the target gene wr3. The gene wr3 was located between primers NAU3740 and CGR5428 with the distance of 4.8cM and 10.4cM respectively. So, we inferred that wrinkled leaf mutant gene wr3 were located on chromosome 21 (D11)4. Chi-square test of the SSR lociWe obtained the data of 150 SSR loci during the whole experiment. Chi-square test on all the data showed that 18 loci significantly distorted from the expected segregation ratio (P<0.05), accounting for 12.00% of the total loci. There was no influence to the location of wrinkled leaf mutant gene wr3.