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A comparative study of DNA synthesis in cotyledon protoplast cultures of Brassica napus, B. campestris and B. oleracea using an immunocytochemical technique
Author(s) -
Zhao KongNan
Publication year - 1995
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.1995.930111.x
Subject(s) - cotyledon , brassica , biology , protoplast , brassica oleracea , cultivar , nuclear dna , staining , botany , microbiology and biotechnology , horticulture , biochemistry , genetics , gene , mitochondrial dna
The present study was designed (1) to observe the characterization of 5‐bromo‐2′‐dexoyuridine (BrdU) incorporation into cultured Brassica cotyledon protoplasts and (2) to investigate the genetic differences in the levels of nuclear DNA synthesis (expressed by the percentage of nuclei labelled with BrdU) in cotyledon protoplast cultures from 12 cultivars of three Brassica species ( Brassica napus, B. campestris and B. oleracea ) at an early stage using immunocytochemistry. Nuclei labelled with BrdU were different from those showing only staining with 4′‐6′‐diamidino‐2‐phenylindole (DAPI) under fluorescence and light microscopy. Two to 5% of nuclei were labelled with BrdU after 1 h of culture, indicating that nuclear DNA synthesis occurred at a very early stage of culture. The percentage of nuclei labelled with BrdU increased with time over the length of the culture period. The mean percentage of nuclei labelled with BrdU in the 12 cultivars was about 25% at 24 h after culture initiation. The curve of the increase in percentage of nuclei labelled with BrdU exhibited an S‐shape from 1 to 24 h. However, cultivar differences in percentages of nuclei labelled with BrdU were very significant over the time course of 1‐24 h from initial culture, with cultivars Eureka ( B. napus ), Global ( B. napus ), Narc 82 ( B. napus ), Bunyip ( B. campestris ) and Sugar Loaf ( B. oleracea ) having a consistently higher percentage of nuclei labelled with BrdU than the other cultivars. Species differences were also significant, with cultivars of B. napus showing much higher percentages than the tested cultivars of B. campestris and B. oleracea . The results indicate that the differences in nuclear DNA synthesis in Brassica cotyledon protoplast cultures were most likely at both intra‐ and interspecies levels.