2n雄配子的无融合生殖披碱草(Elymus rectisetus)减数分裂行为研究

Studies of the Meiosis of 2n Gamete Apomictic Wheat Grass( Elymus rectisetus)

用能自然产生 2n雄配子的无融合生殖六倍体披碱草为材料 ,研究了无融合生殖披碱草的减数分裂行为。结果表明 :2n雄配子的无融合生殖披碱草减数分裂行为较为异常。在间期细胞内经常有微核存在 ;在前期Ⅰ ,有倒位环、多价染色体等异常现象 ;在中期Ⅰ ,染色体有不等分裂的倾向 ;在后期Ⅰ和末期Ⅰ ,有染色体的单极分裂 ( 63 9% )、染色体走向一极的倾向( 2 1 7% )和多极分裂 ( 3 3% )等现象 ,单极分裂的结果是不减数配子的产生。在减数分裂Ⅱ中 ,有高比例的二分孢子 ( 5 5 7% )和三分孢子 ( 2 3 7% )的形成 ,二分孢子在发育后期也直接导致了 2n配子的产生。因此 ,染色体的单极分裂、二分体和三分体形成这

The formation of polyploid was mainly through the combination of 2n gamete, and the apomixis played an important role in plant evolution and plant breeding. In general, the formation of male gamete and female gamete in apomictic plants are obviously different, ie, the formation of embryo sac was through apomixis (form into 2n female gamete); however, the formation of male gamete was through normal meiosis (form into ln male gamete). The 2n male gamete apomictic wheat grass was more important than ln male gamete apomictic wheat grass, because the 2n male gamete can bring all genes including apomictic gene into other plant. The meiosis of 2n male gamete apomictic wheat grass ( Elymus. rectisetus) was observed through Olympus AH3 microscope; the results showed that the meiosis of 2n gamete apomictic wheat grass was very abnomal. In the interphase, lots of mini-nucleus were found. Inverted cycle, multibivalent and lagging chromosome were also found in the prophase. In metaphase, chromosomes frequently show unequal division tendency; In anaphase I and telophase I, completely unequal division, modified meiosis, the tendency of nucleus fusion and other abnormal phenomena were found. These phenomena directly lead to the production of 2n gamete. In meiosis Ⅱ, the abnormalities mainly lie in the proceeding of microspore, dyad (55.7%), triad (23.7%) and tetrad (21.6%) were found. The abnormal of those proceeding also lead to the production of 2n gamete.