XVI International Botanical Congess

PCR fragments homologous to the Arabidopsis genes leafy and apetala1 have been isolated from kiwifruit. Northern hybridization analyses have shown that these genes have bimodal patterns of expression in developing shoot buds and this is consistent with the two-year cycle of bud and flower development seen in kiwifruit. The first peak of expression occurred early in bud development when floral meristems are initiated and the second, approx 9 months later, when flowers differentiate. In situ hybridasation analyses on buds collected early in development have shown that the leafy-homologue is expressed in developing leaf primordia and bud meristems, whereas expression of the apetalal-homologue is localised in meristems only. These results suggest that apetalal-homologue expression is a useful marker for floral commitment in kiwifruit and that it occurs very early in bud development.