Studies On The Difference Of Extra Chromosomal Transmission Frequency Through Female Gamete Between Distinct Trisomics In Chinese Cabbage

In order to find out the main factor of the discreasing of extra chromosomal transmission frequency through female gamete, the primary trisomics.- Tri.-6, Tri.-7, Tri.-9, Tri.-l0 and Tri.-3,6 as materials, and their gametophyte development, pollination, fertilization and embryo development were systematically studied; the seeding set and the germination rate were investigated. The results were as follows:(1) Extra chromosome of all other trisomics could be transmitted through female gamete except Tri.-l0, just the transmission frequency was different. The transmission frequency of Tri.-3, Tri.-6, Tri.-7, Tri.-9, was 7.69%, 8.69%, 22.20% and 17.74%, respectively.(2)The situation of female gametophyte development and embryo development:The analysis indicated that the rate of embryo sac abortion was different for these trisomics. The abortion rate of Tri.-3, Tri.-6 and Tri.-9 was equal to the diploid, it was 25.31%, 24.81% and 28.94% respectively; and to Tri.-lO and Tri.-3,6, the abortion rate was much higher, it was 83.75% and 68.16%, respectively.During the embryo development, the abortion rate of young embryo was different. The abortion rate of Tri.-3,6 was much higher, and it was 14.16%; the abortion rate of Tri.-3 and Tri.-9 was relatively high, it was 9.40% and 6.83% respectively; Tri.-6 was equal to the diploid to abortion rate of young embyo; To Tri.-lO, because the young embyo was not formed, its abortion rate was 0.(3) The seeding set and the germination rate between different trisomics were different. The seeding set of Tri.-9, much higher, was 44.00%, and thegermination rate, very low, was 10.00%: The seeding set of Tri.-3 and Tri.-6, relatively lower, was 25.00%, and their germination rate was 56.00% and 25.00% respectively; Tri.-l0 did not form seeds; the seeding set and germination rate of Tri.-3,6, much lower, were 2.82% and 16.60%, respectively.(4) The main factors that led to the decreasing of extra chromosomal transmission frequency of these trisomics were different. To Tri.-3, the main factors were low fertilize rate, higher abortion rate of young embryo, and low germination rate; to Tri.-6, the main factors were low fertilize rate and germination rate: to Tri.-9, the main factors were high abortion rate of young embryo and low germination rate; it was the abortion embryo sac that led to the discreasing of transmission frequency of Tri.-l0; to Tri.-3,6, the main factors were high abortion rate of embryo sac, low fertilized rate, high abortion rate of young embryo, and low germination rate.(5)The morphological character of distinct trisomics was different. The plant of Tri.-9 behad false normal; the plant of Tri.-6 and Tri.-7 behad relatively special.