甘蓝型油菜细胞质雄性不育系NCa花药发育的细胞学观察

Anatomical Observations of Anther Development of NCa, a Cytoplasmic Male Sterile Line in Rapeseed( Brassica napus L.)

NCa不育系是从甘蓝型油菜与埃塞俄比亚芥的远缘杂交后代中选育出来的。利用光学显微镜和透射电镜对NCa不育系的花药发育过程进行了显微结构和超微结构观察。结果表明,NCa雄性败育发生于单核花粉晚期。其主要特点是:花粉母细胞可以通过减数分裂,四分体可以释放出小孢子,释放出的单核小孢子可以继续发育并在早期形成花粉壁,但是晚期单核花粉细胞质和细胞核相继降解,仅剩下含大液泡或内空的花粉壁;在四分体时期以前绒毡层与正常花药组织的无异,但随后细胞质开始逐渐小液泡化并最终解体。与已经研究过的其它油菜细胞质不育系相比,该不育系的败育时期相对较晚;其花药败育特点明显不同于已研究过的所有油菜胞质不育类型。

A cytoplasmic male sterile (CMS) line, named NCa, was obtained from the backcrossing descendents of hybridization between two amphidiploid species of Brassica napus L. (AACC, 2n =38) and B. carinata (BBCC, 2n =34), respectively. The anatomical observations on the anther development of NCa by light microscope and transmission electron microscope showed that the abortion of the anther development occurred at the later mono-nucleus microspore (MNM) stage. The microspore mother cell of NCa could pass through meiosis and form tetrads and then tetrads could release microspores as the same as the fertile line. The released microspores with one nucleus could continuously develop and form pollen wall soonly. The protoplast and nucleus of MNM degraded in succession and just left the empty pollen wall at last or with large vacuoles. The tapetum development was similar to that of the fertile anther up to tetrad stage but after that the protoplast of tapetal cell was rich in small vacuoles and degenerated gradually. Anther development of NCa sterile line was obviously different from all of the other kinds of CMS lines examined before, because its abortion stage revealed here was later than any of the examined CMS types and it formed pollen wall soon after microspores released and remained that until pollen degradation.