不同生育期转Bt基因棉根系分泌物中氨基酸、有机酸等组分特征

摘要

The component characteristics including organic acids, amino acids and Bt proteins of root exudates at different growth stages (seedling, seedling stage and bud stage)from transgenic Bt cotton and conventional cotton were studied. The results showed that the pH of transgenic Bt cotton and common cotton root exudates decreases gradually in the growth period, from the alkaline in seedling stage(>8.0)to the subacidity of the bud stage(<6.8); The water-soluble carbon,water-soluble nitrogen, Bt proteins, organic acids, amino acids and total soluble sugar were increased significantly with the extension of growth period. At the same growth stages, there were no difference in main components of the two cotton root exudates, but the most root exudates component of conventional cotton(such as the water-soluble carbon, water-soluble nitrogen, total solu-ble sugars, amino acids, organic acids, etc.)were higher than those in Bt cotton, especially in the bud stage. As the main organic acid in the root exudates, formic acid in transgenic Bt cotton root exudates accounted for 55%, 75% and 93% at the young seedling, seedling and bud stages, respectively, and that in conventional cotton root exudates accounted for 65%, 39% and 96%, respectively. Therefore, the content of the formic acids was the main difference in the organic acids between the conventional and transgenic Bt cottons. As one of main amino acids in root exudates, threonine in the transgenic Bt cot-ton and conventional cotton at the bud stage accounted for 42% and 36%, respectively. Compared to the transgenic Bt cot-ton, the conventional cotton root exudates could provide more carbon and nitrogen resources for plant growth.%通过水培抗虫棉及其亲本棉,研究不同生育期(幼苗期、苗期和花蕾期)棉花根系分泌的有机酸、氨基酸及Bt蛋白等分泌组成特征.结果表明,转Bt基因棉和常规棉根系分泌物的pH随生育期逐渐降低,由幼苗期的碱性(>8.0)转变为花蕾期的弱酸性(<6.8);根系分泌物中水溶性碳、水溶性氮、Bt蛋白、有机酸、氨基酸及可溶性总糖随着生育期的延长显著上升.相同生育时期,两种棉花根系分泌物主要组成成分无差异,但是大多数组分(如水溶性碳、水溶性氮、可溶性总糖、氨基酸、有机酸等)的含量表现为常规棉>转Bt基因棉,且花蕾期差异最显著.甲酸为根系分泌物中有机酸的主要成分,在幼苗期、苗期和花蕾期,转Bt基因棉根分泌物中甲酸分别占有机酸含量的55%、75%、93%;常规棉根系分泌物中甲酸分别占有机酸含量的65%、39%、96%,因此,转Bt基因棉和常规棉甲酸含量差异是引起有机酸差异的主要原因.苏氨酸是根系分泌物中氨基酸的主要成分,在花蕾期,转Bt基因棉和常规棉根系分泌物中苏氨酸含量分别占总氨基酸的42%和36%.与转Bt基因棉相比,常规棉根系分泌物中含有更为丰富的碳、氮源物质.