芥菜型油菜与白菜正反杂交的胚胎学研究

Embryologic Research into Reciprocal Crosses Between Brassica juncea and B. pekinesis

利用荧光技术对芥菜型油菜(Brassicajuncea)与白菜(B.pekinesis)种间正反杂交后花粉萌发和花粉管生长过程进行了观察。结果显示:芥菜型油菜与白菜正交授粉后,花粉在柱头上能正常萌发,多数花粉管沿花柱到达胚珠完成受精,且受精方式有珠孔受精、合点受精和中部受精,少量花粉管生长不正常,出现花粉管顶端膨大扭曲,花粉管分支等异常现象;反交授粉后,花粉在柱头上萌发时柱头乳突细胞产生强烈胼胝质反应,影响花粉管生长,只有少量花粉管通过花柱到达胚珠完成受精。用石蜡切片技术观察了正反杂交后杂种的胚胎发育,正交杂种胚胎发育较早,胚和胚乳生长较正常,杂种胚一般均能发育至成熟;反交杂种胚发育至心型期便不能继续发育,胚乳也停滞在游离核阶段并最终败育。综合分析表明,芥菜型油菜与白菜正反杂交都存在一定程度的受精不亲和性。

We used fluorescence observation to examine pollen germination and growth following reciprocal crosses between Brassicajuncea and B. pekinesis. When B. juncea was used as the seed parent, the pollen grains on the stigma could sprout as usual, and most of the pollen tubes could reach the ovule through the style and finish fertilization. With fertilization type, porogamy, chalazogamy and misogamy included, only a few pollen tubes grew poorly and gave rise to the end being swollen and twisted as well as branched pollen tubes. With B. pekinesis used as a seed parent, the growth of the pollen tube was restrained, so only a little tube could go into the ovule and fertilize the eggs because of papilla cells with strong callose effects. The development of a hybrid embryo derived from the reciprocal crosses was observed by means of the paraffin-cut section method. B. juncea and B. pekinesis crossed embryos developed early and in general grew to maturity, and the growth of the embryo and endosperm was relatively normal, whereas in the B. pekinesis and B. juncea hybrid embryo, growth stopped at the heart-shaped stage as did growth of the endosperm at the dissoluble nuclear stage, and finally disappeared in the seed. Thus, B. juncea and B. pekinesis and its crosses are incompatible to some degree.