Studies On Chemical Methods And Correlative Mechanisms Of Overcoming The Self-incompatibility Of Brassica Oleracea L.

Heterosis is significantly notable in Brassica oleracea L. Cruciferae, which has been applied widely in breeding. At present, most of the crossbreeds of B. oleracea L. are obtained from hybridization between self-incompatable lines. In the course of hybridization breeding of B. oleracea L., one of the important problems is the propagation of the SI lines. The bud pollination needs a lot of labors and time, so the cost is high.In the process of reproducing self-incompatible lines, for the sake of reducing the self-incompatibility (SI) of B. oleracea and keeping it easily in the period of pollination, in this study, a lot of chemical medicaments is selected, the buds or the flowers of SI lines are treated with these medicaments. Then pollinate with the same plant at the different hours of the day after the treatment, the legumens are harvested separately after the maturation, the legumen rate and the SI index are stated. Through comparing with the result of the bud pollination, the validity of medicaments to overcome the SI is determined. In the same time, we also traverse the overcoming mechanism with two efficient medicaments. The results of our studies are following:The field trial results shows: All of the SI plants treated with these medicaments are more efficient than the untreated SI plants. It proves that it is available to overcome the SI of Brassica oleracea significantly with chemical medicaments. But we analyse the treated behaves on the three self-incompatible lines, we can classify the treatments three kinds. The best kind overcoming SI is the 5%NaCl solution, its average NO.of seeds per flower is 5.56 higher than the other treatments, and is similar to bud pollination. The second kind is 5%KH2PO4 and 0.1%plant lectin, the NO.of seeds per flower ( 2.61 and2.19 separately)is higher than that of flower pollination but lower than that of bud pollination. The thrid kind is 0.1 %KT, 0.1%Ser and 75%alcohol solution, the NO.of seeds per flower (under 2) of SI plants treated with them is higher than that of flower pollination, but the effect is not ideal, so we do not make further studies.In addition, we treat the SI plant stigmas with NaCl+ boric acid solution in three consideration(3%NaCL+0.2% boric acid, 5%NaCL+0.3% boric acid, 8%NaCL+1% boric acid solution) separately. The result shows, in this trial, the best consideration is 5%NaCL+0.3% boric acid. The average NO.of seeds per flower reaches 6.0, the highest is 7.68. At the same time, the effect is related to the hours after treating. The text result showed that it is good to pollinate the SI lines with treating after half an hour. On the base of the field text, we make it thorough studies for its overcoming mechanism. By many ways of studies, we conclude that its overcoming mechanism is following: The overcoming mechanism of NaCL+ boric acid solution is that it denature the SI plant stigma protein and change its polarity, so the stigma protein can not identify the SI pollen or SC pollenes. therefore the SI pollen can sprout on the stigma. On the one hand, By means of fluorescent microscopy, the self-incompatibility of B. oleracea is stained with aniline blue and observed in 7h after pollinating. The study find that the main barrier to self-pollinate was that pollen grains can not germinate and pollen tubes failed to penetrate stigma whose surface produced serious callose reaction, giving rise to the distortion of pollen tubes, swelling of their tops and failure to growth. In the same time, the effect on stigma papilla cells with 5%NaCL solution treatment is studied, the amount of callose in surface cells of the stigma and the incompatibility tend to reduce. Most of the pollen grains are able to germinate and the pollen tubes could elongate.At the same time, with the aid of scanning electron microscope, we observed that the pollen grains failing to germinate in 12 hours after pollination would shrink and become small, finally up to shrivel. Other pollen grains germinate from its bourgeon channel, the rest bourgeon channels become shrink.