Sterile Stability Of Four Genetic Male Sterile Lines And Genetic Male Sterile Gene Localization In 1355A

Heterosis is a common phenomenon, and hybrid vigor is vritical to improve cotton fibre productivity and quality. Recessive genetic male sterility is one route to utilize heterosis as for crops without prefect three lines. This paper studied sterility stability of four genetic male sterile lines by field investigation on sterility and pollen vigor test in laboratory. Molecular markers locatization of GMS 1355A genetic male sterile gene ms₂ had been researched, therefore it is expectated that ms₂ can be used to improve breeding efficiency of cotton genetic male sterile lines by molecular marker assistant selecting. The results are as follows:Sterile stability investigation of four genetic male sterile linesThis study investigated sterility stability of four upland cotton GMS two utilization lines GA₃, 1355A, Zhong12A and LangA in summer of 2005, and sterility instability phenomenon was found in these four GMS lines. Relatively the sterility stability of 1355A is the best with instability plants ratio 14.3%. Sterility instability plants ratio of LangA and Zhong12A are 38.9% and 36.7%, respectively. Several instability types of instability plants and the ratio of instability types are different among four genetic male sterile lines.Four F₂ populations of these GMS lines were constructed and sterility stability was investigated again in 2006. The result further indicated that the sterility stability of 1355A is the best with sterility instability ratio 11.9%, and LangA is the worst line with sterility stability ratio 20.3%. The instability ratio obtained in 2006 is lower than that in 2005, but the instability order of four lines had no change. These results hinted that sterility instability phenonmenon really exist in genetic male sterile cotton.Furthermore this study researched sterile flower ratio of four GMS lines at different development stages. It was resulted that the ratio change related with sterility instability. GMS 1355A, a better sterility stability line, has a few changes of sterile flower ratio. Zhong12A & langA are the worse sterility stability lines and showed more changes of sterile flower ratio. Additionally sterile flower ratio has the same trend with sterile degree of sterile flower, and few normal pollen were detected in some of sterile plants.Pollen vigor test indicated that pollens of four GMS two utilization lines and their F₂ populations had strong vigor which showed no obvious changes under room temperature for one day.1355A genetic male sterile gene ms₂ localizationWe constructed F₂ population containing 192 fertility stability individuals of GMS 1355A and two DNA pools (respectively containing 10 sterile individuals and 10 pur-fertile individuals). A total of 1545 SSR primer pairs and 238 SRAP primer combinations were used to detect the polymorphisms between two pools. As a result 40 primers (32 SSR primer pairs, 8 SRAP primer combinations) showed polymorphism between two bulks. Twelve individuals containing 5 pur-gene type fertile plants and 7 sterile plants were scaned using the 40 primers again. The better primers were used to survey F₂ population of 192 individuals.Totally 10 primers (8 SSR primer pairs, 2 SRAP primer combinations) showed polymorphic in F₂ population, and they generated 12 polymorphic loci. Linkage analysis indicated 3 SSR primers pairs (4 loci) were linkaged closely to genetic male sterile gene ms₂. The distance between markers BNL3932₈₀₀, BNL3932₈₇₀ and ms₂ was only 1.56cM and 2.08 cM, respectively. The marker CIR295, BNL236 both were on the other side of ms₂ with genetic distance 3.23cM and 4.76cM, respectively. So the upland cotton genetic male sterile gene ms₂ was localized on Chr14 for the first time.