Abstract: Oilseed rape plants disperse their seeds by pod-shattering known as Pod dehiscence, which causes yield loss. To investigate the effect of structure differentiation on pod shattering, we studied the developmental process and structural characteristics of fruit “dehiscence zone” of two varieties with different pod shattering behavior Zhongshuang 9 and Zhongshuang 11, by semi-thin section fluorescence microscopy with. Our observations revealed that: (1) rape pod gradually differentiated to form “dehiscence zone” in fruit development, which was composed of dehiscence zone (or separation layer), lignified valve edge, lignified endocarp b and replum cells; (2) The dehiscence zone of Zhongshuang 9 was found at 15DAF (day after flowering), and meanwhile the walls of valve edge cells, endocarp b cells and replum cells were thickened, and that of Zhongshuang 11 did not show these features until 25DAF. The dehiscence zone was fully formed in Zhongshuang 9 at 25DAF, while in Zhongshuang 11 at 30DAF.The separation of dehiscence zone cells was observed at 30DAF in Zhongshuang 9, while this occurred in 35DAF for Zhongshuang 11. In addition, more cell separation sites occurring between lignified replum cells enhanced pod shattering in Zhongshuang 9. These results provide a theoretical guidance for molecular regulation of pod shattering and oilseed rape breeding for pod shattering-resistance.

Key words: Brassica napus pod, Dehiscence zone, Differentiation, Fruit shatter