八倍体小偃麦与普通小麦及其杂种F1的小孢子发生和花粉发育的细胞学观察

CYTOLOGICAL OBSERVATIONS OF MICROSPOROGENESIS AND POLLEN DEVELOPMENT IN TRITICUM SECT.TRITITRIGIA, T. AESTIVUM AND THEIR HYBRIDS

两亲本'小偃7430'和'烟农15'小孢子发生正常。在花粉发育过程中,小孢子第一次有丝分裂时两者都有败育情况发生,但败育率前者高于后者。二核及三核期花粉发育正常,两亲本结实率也基本正常。(小偃7430×鲁麦1号)F_1和(小偃7430×烟农15)F_1花粉母细胞减数分裂过程非常紊乱,中期Ⅰ出现较高频率的单价体及多价体,后期Ⅰ出现落后染色体,四分体期出现较高频率的微核,但在小孢子第一次有丝分裂时,其败育率与'小偃7430'类似,均在10%左右。二核及三核期花粉发育基本正常,但植株结实率却显著低于两个亲本,分别为28.24%和33.82%。花粉败育不是导致杂种F_1结实率降低的主要因素。

Cytological observation of microsporogenesis and pollen development of two parents,Xiaoyan 7430 and Yannong 15, and their hybrids were carried out by using squash method in this study. The results show: that microsporogenesis of the two parents, Xiaoyan 7430 and Yannong 15, is normal but their microspores usually aborted at first meiosis in pollen development. The frequency of abortion is higher in the former than the latter. However, the pollen development of which passed through the first meiosis is normal at the 2- or 3-nucleated stage. The rate of setting of both parents is basically normal. The meiosis of pollen mother cell (PMC) of two hybrids of Xiaoyan 7430×Lumai No.1 and Xiaoyan 7430× Yannong 15 is quite chaotic. Despite of the high frequency of univalents and multivalents at meiotic MI of PMC, and of micronucleoli in tetrad as well of the laggards at meiotic AI observed, the frequency of abortion of microspore are both at about 10%, similar to that of Xiaoyan 7430, at first meiosis of microspore in the stage of pollen development. Even though the pollen developments are basically normal in the 2-or 3-nucleated stage, but the percentage of setting of two hybrids is 28.24% and 33.82% respectively, apparently lower than that of their parents. The above-mentioned results indicate that although meiosis of PMC of F1 is chaotic, yet normal microspore could be formed and stages of pollen development can still be carried on. The lower seed setting of F1 is not mainly due to abortion of pollen.