Fine Mapping Of The Dominant Glandless Gene Gl₂^e In Cotton

Cotton is a fiber, oil and feed crop. Cultivated cotton, as well as some wild species, contains gossypol,a polyphenolic compound that is major factor of the cotton plant’s self-defense system against insect pestsand possibly some diseases, but it is toxic for human and non-ruminant animals consumption. Consequently,attempts have been made to remove the substance through breeding in order to utilize the cottonseedeffectively, It has become the research emphasis to breed pigment glandless cotton all of the world. As farthe researchers have developed glandless cotton cultivars, but the cultivars were controlled by recessivegene, which lost so many excellent characters because of natural crossing in the cultivated cotton.Appearance of dominant glandless gene Gle2in cotton provides an important gene resource in glandlesscotton breeding undoubtedly. But so far there is no report about the isolation and cloning of the Gle2gene.In this study，we used SSR molecular markers combined with cotton genome sequence data to locatethe Gle2gene by fine mapping. Results are as follows:We constructed2302F2by making cross between CRI12and Glandless CRI12as parents. Parents arethe Near-isogenic line（NILs）. It has been made to investigate on the F2population in different developmentperiod and different positions, the F2population has600plants with dark-colored glands,1110plants withlow-glands, and592plants with no gland. Chi-square analysis showed that the segregation ratio was1:2:1（x2=0.708<x20.05,2=5.99）, which further confirmed that glandless character was controlled by anincomplete dominant gene, Gl₂^e. This result was consistent with observations previously reported.SSR maker NAU2251is closely linked with dominant glandless Gle2genes, Based on the the G.arboreum （A genome） sequence data（data not published）, the SSR maker NAU2251is anchored on thescaffold of the G. arboreum （A genome） sequence. The new SSR markers were developed from the scaffoldsequence, and the glandless Gle2gene was located within an interval of340Kb using the new markerscombined with the phenotypic traits analysis within the200plants of the F2population.In further experiments, the target gene, Gl₂^egene are locked in the7.5kb region of scaffold using SSRanalysis combined with all of the plants of F2population. And fluorescence quantitative PCR has been doneto test the difference between the dark-colored glands and glandless plants, The result showed that there are expression difference between the gland and glandless plants. But further investigation is needed to validatethe target gene.