Studies Of Pollen Abortion Mechanism Of Two New Brassica Napus Male Sterility Lines

Male sterility was utilized widely in crossbreeding. And now it is one of the most important methods in this field. To provide the study of the abortion mechanism, microsporogenesis of the Brassica napus cytoplasmic male sterility (CMS) "Long You 9" and Genic male sterility (GMS) X (Unnamed, all were this variety if there was no indication) were studied under light microscopy and electronic microscopy in present works. The changes of cytoarchitecture were investigated, and some evidences for the abortion occurring was revealed as following:1) The CMS "long you 9"was taller than its maintaining line. The corolla couldn't open;the petal was thin and covered by the calyx. Or the corolla could open, but the petal was long, narrow and upstanding. The anther was hollow, thin, and sharp in its top end. In the aspect of the sterility, the anther of CMS "long you 9"showed male sterility partly in May, which temperature was comparatively low. And that the abortion was entire in June, which temperature was comparatively high. It showed that the abortion of "long you 9"was relative to temperature in a large degree. The GMS X was same with the normal Brassica napus in appearance, but the petal was a bit of smaller than the normal line at the end of the florescence. The anther of the GMS X was synchronized with the normal line in early stage (before 2mm), then shrunk gradually.2 ) The half-thick slices showed that the characteristics of abortion of the CMS "long you 9" were not distinct. When the mean temperature was low, it could be seen in the CMS "long you 9"that the locule couldn't differentiate, the sporogenous cell was collapsed, or the tapetum and microspore were abnormal. The microsporogenesis of GMS X before the stage of the pollen mother cell (PMC) was normal, and the abortion occurred in the stage of meiosis II of the PMC. The main characteristics were that much vacuole emerged in the PMC, the callose accumulated asymmetrically, and the cytoplasm condensed.3) Difference was showed in ultrastructure between the GMS X and thenormal line, too. ?Large amounts of multivesicular bodies (MVB) and autophagosomes appeared in the cytoplasm, then the MVB diffused to the whole cell, and the abortion was occurred successively.?Most of the PMC nucleuses were covered by unit membrane, which is up to four layers. These membranes were considered to be come from the Endoplasmic reticulum(ER).They held back the exchanges of matter, energy and information between the cytoplasm and nucleus terribly and did a very important action in abortion.?Some differences were observed in the Plasmodesma (PD)/ Cytoplasmic channel (CC), too. More substances passed through the PD/CC in normal Brassica napus than in the GMS X;This evidence revealed that there were more difficulties in material exchanging between the PMC of the GMS X. And it argued that the PD/CC played an important role in microsporogenesis.