3种生殖方式蒲公英花粉活力和柱头形态及可授性对比

利用离体萌发法、电镜扫描和联苯胺-过氧化氢法对有性生殖的东北蒲公英、专性无融合生殖的丹东蒲公英和兼性无融合生殖的蒙古蒲公英花粉活力、柱头表面形态及可授性进行观察和测定。结果显示:(1)3种蒲公英柱头均为干柱头,单细胞乳突,属于原始进化类型,都存在雌雄异熟和雌雄异位花部特征;东北蒲公英乳突饱满、紧密,蒙古蒲公英次之,丹东蒲公英干瘪、稀少。(2)东北蒲公英和丹东蒲公英柱头呈Y状时期花粉萌发率最高,分别为67.3%和19.8%,蒙古蒲公英柱头呈棒状时期萌发率最高,为23.3%。(3)3种蒲公英随着开花进行,柱头可授性增加,并且柱头在大Y状时期3种蒲公英为最佳授粉期,可授性柱头占样本柱头的比率分别是98.7%(东北蒲公英)、84.0%(蒙古蒲公英)、21.3%(丹东蒲公英)。研究表明,有性生殖蒲公英与无融合生殖蒲公英在花粉萌发力、柱头可授性和乳突上产生明显差别,为蒲公英在长期进化中性器官能量再分配提供证据。

Comparation of Pollen Viability and Stigmatic Surface Morphology and Receptivity in Three Reproductive Strategies of Taraxacum

We investigated pollen viability and stigmatic surface morphology and receptivity in sexual reproduction of Taraxacum ohwianum Kitag.,obligate apomicts of T.antungense Kitag.,facultative apomicts of T.mongolicum Hand.-Mazz.using germination in vitro and techniques of scanning electron microscopy and benzidine-hydrogen peroxide test.The result showed that:(1)Three kinds of dandelion stigma were dry stigma,single-celled papilla and belong to the primitive taxa.The phenomena of dichogamy and herkogamy appeared in dandelion.The papilla of T.ohwianum Kitag.was full grown and tight,T.antungense Kitag.was more wizened and T.mongolicum Hand.-Mazz.was the most wizened and rarefaction.(2)When stigma was in the Y-type ,the pollen germination capacity rate of T.ohwianum Kitag.and T.antungense Kitag.was the highest,at 67.3% and 19.8% respetiviely.The highest rate of pollen germination capacity of T.mongolicum Hand.-Mazz.was 23.3% when stigma was in stick-type.(3)The stigmatic receptivity of three kinds of dandelions was rising with flowering.When stigma was in the Y-type,it was the best pollination period on the kinds of dandelion and the rate of stigmatic receptivity in samples were 98.7%(T.ohwianum Kitag.),84.0%(T.antungense Kitag.),21.3%(T.mongolicum Hand.-Mazz.),respectively.There was transparent difference of sexual reproduction of dandelion and apomicts of dandelion in pollen germination capacity,papilla and stigmatic receptivity,which was an evidence of the redistribution of energy in sex organ of dandelion in long term evolution.