Nuclear DNA endoreduplication during petal development in cabbage: relationship between ploidy levels and cell size.
The development of cabbage petals comprises two distinct phases: a cell division phase and a consecutive phase of cell expansion until the onset of opening. In this study, cytological changes characterizing the two phases of petal development were analysed. First, the mitotic activity and the surface area of epidermal cells during petal development were investigated. The DNA content of isolated nuclei from the different stages of petal tissues was determined by flow cytometric analysis. The results show that cell differentiation, leading to expanded cells, is characterized by endoreduplication. In the proximal part of the petal, after cell division arrest, differentiation frequently involves endoreduplication and cell enlargement. By contrast, normal diploid nuclei remained in the distal part of the lamina in the mature petal. It is suggested that the developmental programmes of the cabbage petal may be a trigger for the initiation of endoreduplication. Correlation between ploidy levels and cell size is also discussed.
Kudo
Nobuhiro
N
Division of Plant Biotechnology, Gunma Horticultural Experiment Station, 493 Nishi-Obokata, Sawa-Azuma, Gunma 379-2224, Japan. kudon@aic.pref.gunma.jp
Kimura
Yasuo
Y
D001937:Brassica / Q000166:cytology / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics*; D048429:Cell Size / Q000235:genetics; D004261:DNA Replication / Q000235:genetics; D018744:DNA, Plant / Q000032:analysis*; D005434:Flow Cytometry; D018507:Gene Expression Regulation, Developmental; D008940:Mitotic Index / Q000379:methods; D019441:Plant Epidermis / Q000166:cytology; D018514:Plant Structures / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D011003:Ploidies
D018744:DNA, Plant