Studies On Development Of Oil Body And Correlation Between Oil Body And Oil Content In Rapeseed (Brassica Napus L.)

Embryogenesis, oil body development and seed maturation of rapeseed show close correlation with the oil content of seed. The process of embryo development of the cultivar ZH-088 of Brassica napus (L.) was studied with the convenient method of direct dissection. The result showed that the embryo development of ZH-088 undergoes the globular, heart, torpedo, Y, walking-stick, U and V stages subsequently, until the seed desiccation. The duration of the whole embryogenesis was about 50 days, and similar to the winter rape. However, the embryo development of ZH-088 was slower than that of some reported spring rape cultivars, such as "Marnoo". In addition, the color of the embryo went through light green, dark green, dark brown and tan.Moreover, an efficient method of oil body observation in rapeseed with the aid of fluorescent dye Nile Red and laser scanning Confocal microscopy was set up in this study. The process of oil body development of different rapeseed cultivars observed with this Nile Red-Confocal method. In the cotyledon storage cells, a few oil bodies were distributed in the centre at 19 day after flowering (daf). Almost no increase of the size and number of oil bodies were found from 19 daf until 40 daf. However, the volume and number of oil bodies per cell increased dramatically during 40-45 daf. At 45 daf, all oil bodies turned to globular bodies, and localized in the middle of the cell. At 50 daf, the quantity of oil bodies increased slightly, and the bodies were tightly packed but kept separate from each other. Oil bodies were polygonal upon seed maturation. The process of oil body developments of the low-oil cultivar ZL-366 mimicked that of ZH-088. However, during the period of 40 daf to seed maturation, compared with high-oil cultivar ZH-088, low-oiled ZL-366 had smaller population of uniformly-sized oil bodies in its cotyledon storage cells.To investigate the correlation of oil body development and oil content of rapeseed, oil bodies in the cotyledon storage cells of mature seeds of six Brassica napus (L.) cultivars, Ningyou14, Ningyou18, ZH-088, ZL-366, NjY008 and Westar were analyzed. In mature seeds, oil bodies were distributed at the central region of the cotyledon storage cells, mostly in elliptical or irregular shape. The statistical result showed that seeds of the high-oiled group contain more oil bodies per cell and have larger volume than that of lower-oiled group. These results provide evidence that the quantity and total volume of oil bodies are correlated with oil content of rapeseed.