The Study On The Mechanism Of Abnormal Plantlet In Agrobacterium-mediated Transformation In Cotton (Gossypium Hisutum L.)

The agrobacterium-mediated transformation is a main useful method in cotton transformation, in which induce the abnormal plantlet would be more than 90% during the regeneration of plantlet, which becomes the bottleneck of cotton transformation and restricts the efficiency of the cotton transformation.Fiber-improvement transgenic cotton plants were obtained by Agrobacteriwn-mediated transformation and were identified by PCR amplification. The main technical parameters were improved, the genotypes of cotton acceptors were widened, and a high efficient system of transformation of four varieties was established. The results showed the surviving rates of the regeneration transgenic plants of different varieties exceeded 90% by grafting.The chromosome aberrance of cotton embryoid was observed. All of the four varieties cotton occurred Chromosome aberrance, and cells with 27~52 chromosomes were the majority in the aberrant cells. Different varieties had different rates of aberrance; the varieties with poor capacity of somatic embryogenesis had a higher rate of aberrance chromosome.Callus, embryogenetic callus, embryoid, abnormal plantlet and normal plantlet of different varieties were obtained from a same media in the induction stage. The normal and abnormal embryoid were distinguished by the rate of normal plantlets induced and the regeneration modes of the cottons varieties were compared to two ways, one with the highest rate of normal inducement was the normal way of regeneration plantlet from callus, embryogenetic callus, global embryoid, heart-shape embryoid, torpedo-shape embryoid, cotyledon embryoid to normal plantlet, etc, the other with the lowest rate of normal inducement was the abnormal way from callus, embryoid callus, global embryoid-like, heart-shape embryoid-like, fish torpedo-shape embryoid-like, cotyledon embryoid-like, abnormal plantlet to normal plantlet, etc. The procedure of seed development and the seed germination as the controls were compared to two ways to measure the changes of the endogenous hormones contents during the induction stage of cotton abnormal plantlets. The results showed that the stage of olivine embryogenic callus and the global embryoid were the key stages during induction stage of the plantlet.The contents of Endo-hormones in abnormal induction plants were higher than that in the normal induction plants after the stage of global-embryoid; abnormal induction plantlets maybe resulted from the lower contents of IAA and ABA in the stage of global-embryoid and a little slowingdown of CKs, thereafter, delaying of the peak ratio of IAA/ABA possibly caused the induction of abnormal plants as a factor. To induce the normal plant and embryoid, reducing the content of lAA/CKs after heart-shape embryoid was suggested.