Regulation Of IAA On Sugar Metabolism In Cotton Fiber Development Stage

IAA is a hormone that plays an important role in the development of cotton fiber.In fact,the development of cotton fiber is also a process of continuous circulation of sugar metabolism.To study the mechanism of IAA regulating cotton fiber differentiation and development,it is necessary to clarify the relationship between IAA and sugar metabolism in the process of fiber development,and whether IAA regulates fiber differentiation,development and elongation by regulating sugar metabolism.Therefore,the dynamic changes of sugar metabolism related to sugar(sucrose,fructose,glucose)content and enzymes(sucrase,sucrose synthetase,sucrose phosphate synthetase)activity were compared in different treatments and different parts of cotton boll(ovule / seed,fiber,cotton boll shell)by using the iaaM transgenic cotton germplasm IF11,to study the relationship between them and the change of IAA content,and to explore the regulatory effect of IAA on sugar metabolism in cotton fiber development stage.The results are as follows:(1)The dynamic changes of sugar content,enzyme activity related to sugar metabolism and IAA content in different parts of cotton boll during fiber development were determined.The total amount of soluble sugar decreased in seeds and fibers,but in boll shell it decreased at first then increased and later decreased again.Sucrase activity decreased in seed and fiber,but in boll shell it increased at first then stabled and decreased,with the higher activity at 5-30 DPA.The change trend of sucrose synthetase activity was a single peak curve,which first increased and then decreased.The peak value in seed and fiber was 30 DPA,and that in boll shell was 20 DPA.The change trend of sucrose phosphate synthetase activity in seed was up-down-up,in fiber was up-stable-down,in boll shell was up-down-up-down,the higher value in seed and boll shell was 10 DPA,and the higher value in fiber was 20-30 DPA.IAA content in cotton boll shell decreased at first then increased and later decreased again.,0 DPA was the highest value,and reached the second peak at 30 DPA.(2)The results showed that the increase of IAA content at the initial stage of fiber development had a trend of "decreaseing first and increasing later".In the early stage,sucrose was decreased,and in the later stage,the content of sucrose,glucose and fructose increased.(3)IAA can promote the activity of enzymes related to glucose metabolism.The activities of sucrose synthetase and the peak of sucrose synthetase activity at 20 DPA and 40 DPA,the activities of sucrose synthetase after 20 DPA,the activities of sucrose synthetase during 10-40 DPA and after 40 DPA in seeds,the activities of sucrose synthetase at 0 DPA and 30 DPA in boll shell,the activities of sucrose synthetase during 5-40 DPA and 0-5 DPA in cotton boll shell were increased activity of sucrose phosphate synthetase.(4)IAA content was positively correlated with sucrose content and glucose content in fiber,sucrose content in seed,sucrose synthetase activity and sucrose phosphate synthetase activity in fiber,sucrose synthetase activity in seed and sucrose phosphate synthetase activity in cotton boll shell,and sucrose synthetase activity in cotton boll shell.It is most closely related to the activity of sucrose phosphate synthetase in fiber.