Chromosome Transfer among Pollen Mother Cells of Garden Crotons (Codiaeum variegatum Blume)

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Codiaeum variegatum shows wide spectrum variability in chromosome numbers among cultivars and plant cells. Chromosome instability in somatic cells has been attributed to endoreduplication, irregular chromosome segregation, spindle multipolarity and unusual nucleus shape. Cytological studies of microsporogenesis in garden crotons revealed that chromosome transfer between microsporocytes in early meiosis might also be included in the row of abnormalities responsible for variations in chromosome number. Six in 12 plants analyzed presented cytomixis among microsporocytes in frequencies ranging from 0.30 to 10.45%. Transference of few chromosomes to the whole genome was found among 2 cells. Prior to cytomixis, chromatin underwent structural alteration. Plants were male-sterile because cytokinesis did not occur after telophase II and tetrad formation was replaced by four-nucleate coenocytic microspore that underwent degeneration prior to callose dissolution.