Effect Of IaaM On The Contents Of Endogenous Hormones,Gossypol, And Root Exudates In The Transgenic Cotton Plant

Transgenic technology has been used widely in cotton breeding, but there were only a few reports on the researches about impact of exogenous gene on transgenic receptors. IF-11is a transgenic cotton material with iaaM gene which can up-regulated the expression of IAA, which can led to the increasing of the fiber numbers on the seed epidermis resulting increasing of lint percentage and fiber fineness at the same time. In order to investigate the effects of exogenous gene on the receptor, the changes of IF-11’s physiological traits except for auxin, such as endogenous hormones, contents of (-)/(+)-gossypol, the composition of root exudate, and the effect of germination and allelopathy were carried out in this experiment, used the non iaaM gene check, the genetic background cultivar, JM-14, and the upland cotton standard line TM-1as the checks. The main results were as follows:(1) The hormone contents of IAA, GA. ZR, and ABA in IF-11, as well as the other materials were analyzed by Elisa. Except for higher contents of IAA, there were also significant differences in GA. ABA and ZR among these different parts of four materials, which may result from the change of IAA contents in different parts of the transgenic plants due to the foreign gene of iaaM.(2) The (-)/(+)-gossypol contents in the different parts of cotton plants among the four materials were determined by the method of pre-column derivatization-HPLC. As the results shown that, among the main organs of the four materials, the total gossypol content in seeds was the highest one as0.344～1.282%; the following by the plant leaves, to be0.221～0.539%. the lowest gossypol content was the stem, only0.031～0.063%. The total gossypol content in the seed and leaves of the IF-11were0.344%and0.221%, respectively, which were significantly lower than that of other materials. There were no significant difference in root and stem among the four experimental materials. The results illustrated that the gossypol metabolism in IF-11was dramatically affected by exogenous gene or higher IAA level of the transgenic plant.(3) There were a large difference among the content of (-)-gossypol and (+)- gossypol in the different parts of the four materials. The (-)-gossypol and (+)-gossypol contents in cottonseeds were0.195~0.589%and0.149～0.693%, respectively; that in the cotton leaves were0.127～0.214%and0.094～0.325%, respectively; that in the stem were0.014～0.029%and0.017～0.034%, respectively in stem; and0.055～0.077%and0.063～0.090%were in the root, respectively. The (-)-gossypol content was higher than that of (+)-gossypol in the seeds and leaves of IF-11, but reversed results were found in other materials. The (-)-gossypol content was lower than that of (+)-gossypol in the stem of the four materials, except for TM-1in which (-)-gossypol cotton was higher than that of (+)-gossypol..(4) The components of the root extrudates of the four experimental materials were analyzed by the method of the gas chromatography and mass spectrometry. As the results showed that there were more materials belong to the hydrophilics group, and less materials belong to saccharides in the root exudates of IF-11, which may inhibit the growth of microorganism around their roots. The result of mycelia growth experiment showed that bacteriostases of root exudates from IF11was better than others, while no difference when compared with IF11(null) which was separated from IF-11. Therefore, it could not concluded from the present results that the root exudate was the main factor which led to the disease resistance of the transgenic plants.(5) The germination experiments showed that the germination percentage and germination vigor were significantly lower than that of IF-11(null). It may result from the exogenous gene or higher IAA and other physiological and biochemical effect. It could be partially improved by several methods such as germination after delinted and presoaking for a few hours etc. The results of allelopathy of cottonseeds shown that extract liquid from IF-11could dramatically promote the germination of ZMS-49, and the effect of allelopathy by IF-11was better than that of IF-11(null) and other materials.