Meiotic Behavior of Male and Hermaphrodite Genotypes of Papaya (Carica papaya L.)

抄録

The aim of this study was to analyze the meiotic behavior and to estimate the meiotic index and the pollen grain viability of three papaya genotypes, male (Cariflora) and hermaphrodite (Golden and UENF/CALIMAN01). In considering of the fact that the genotypes have different flower sizes, initially, meiotic stages were defined in relation to bud size, and, after that, meiosis was observed in the three genotypes. To observe meiosis, flower buds of different sizes were collected and the length of each bud was measured using graph paper. Once the measurements had been taken, two slides were prepared for each flower bud by squashing the anthers in 1% acetic carmine solution. Slides were observed under an optical microscope and for each bud, size was determined as indicating one of three stages, depending on meiotic phase: pre-meiotic, meiotic stage, or post-meiotic stage. In this way, meiosis was observed for the three genotypes, with particular attention given to possible irregularities in cell division in relation to prophase I. It was observed that there is a relation between flower bud size and meiosis. In general, meiosis was normal, but all genotypes showed some meiotic irregularity, with laggard chromosome being the most common. The Cariflora (male) genotype had a higher frequency of irregularities compared to the hermaphrodite genotypes. The meiotic indices estimated for the Golden, UENF/CALIMAN01, and Cariflora genotypes were 92.6%, 91% and 76.9%, respectively; however, the pollen grain viability, on average, was higher than 90%. In conclusion, the meiotic behavior of male and hermaphrodite genotypes was similar, and all three genotypes had some degree of meiotic abnormality.