Sex Expression in Diospyros: Phenological Control of Flower Bud Development in D. kaki and D. lotus

摘要

Blooming time of persimmon (Diospyros kaki: 2n=6x=90) and its synchronicity are often associated with bud endodormancy. The objective of our study is to understand the molecular mechanism of dormancy and flowering in persimmon. To this end; we attempted to use date plum (D. lotus: 2n=2x=30) as a model of persimmon because molecular and genetic studies in persimmon are often hindered by high ploidy level of persimmon. Here, seasonal flower bud development was observed, using D. kaki 'Hiratanenashi' and 'Zenjimaru', which bear only female flowers and both female and male flowers, respectively, as well as male and female trees of D. lotus 'Kunsenshi'. Buds were collected monthly and the internal flower development was observed using scanning electron microscope. Visible flower meristem initiation was commenced by the middle and the end of June in I), lotus and D. kaki, respectively. Following the flower meristem initiation, calyx differentiation progressed during autumn and winter season in D. lotus and D. kaki. However, a prominent progress in petal and stamen/pistil formation was not observed until after endodormancy break both in D. lotus and D. kaki. These results demonstrated that phenological control of flower bud development was similar between these species, suggesting that D. lotus can be used as a model plant for studying dormancy and floral development in persimmon.