Abstract:

【Objective】 The relationship between the ploidy level of microspore-derived plants and chloroplast number in stomatal guard cells was studied in cabbage, broccoli and Chinese kale. 【Method】 Distribution statistics analysis and t-test were used to perform statistical analysis on chloroplast number of different ploidy levels in those stomatal guard cells mentioned above, and morphology identifying and chromosome counting were used to test accuracy of counting chloroplast number in stomatal guard cells. 【Result】 The chloroplast average number in stomatal guard cells was very similar among the different leaf positions on the same plant and among the different locations in the same leaf, while the chloroplast number varied significantly among the different ploidy stoma in the same variety. All the distributions of the chloroplast number in different ploidy stoma were normal distribution fitted. A correlation has been established between ploidy and chloroplast number in the stomatal guard cells. In every single stoma of microspore-derived plants, the chloroplast number for a haploid should not be more than 10, that for diploids should be 11 to 15, and polyploids should be more than 15. The accuracy of this method for identification of different ploidy plants was 93.93%. Further more, the accuracy of this method was reliable and did not vary with the plants growth conditions. 【Conclusion】 Therefore, the chromosome ploidy of plants derived from microspore culture in cabbage, broccoli and Chinese kale can be identified by simply counting the chloroplast number in stomatal guard cells.

Key words: Brassica oleracea var. capitata, Brassica oleracea var. italica, Brassica alboglabra Bailey, stomatal guard cells, chloroplast number, identification of ploidy