Reproductive characteristics for self-compatibility and seedlessness in 'Nishiuchi Konatsu', a bud mutation of Hyuganatsu (Citrus tamurana hort. ex Tanaka)

Abstract

The reproductive characteristics of 'Nishiuchi Konatsu', a bud mutation of Hyuganatsu that is self-incompatible, were examined. A pollination experiment resulted in Hyuganatsu × 'Nishiuchi Konatsu' and 'Nishiuchi Konatsu' self-pollination produced their fruit, whereas 'Nishiuchi Konatsu' × Hyuganatsu cannot produce fruit as a result of early dropping of premature fruits within the first 10 weeks after pollination. Considering the self-incompatible nature of Hyuganatsu, this result implies a mutation of the pollen-expressed gene(s) associated with the self-incompatibility occurring in 'Nishiuchi Konatsu'. When 'Nishiuchi Konatsu' pollen was used for several citrus accessions (Hyuganatsu, 'Nishiuchi Konatsu', Hassaku, and 'Sweet Spring'), it was observed that the number of normal seeds decreased and that of aborted seeds increased. Interestingly, the extent of seed abortion differed among seed parents. Hyuganatsu and 'Nishiuchi Konatsu' lost most of their normal seeds. In contrast, Hassaku lost relatively lesser seeds, and 'Sweet Spring' lost only a few seeds. Moreover, Hassaku fruits obtained by pollination with 'Nishiuchi Konatsu' pollen showed various proportions of normal and aborted seeds even among indivi racteristics were superior in Hyuganatsu-pollinated fruits compared with 'Nishiuchi Konatsu'-pollinated ones in 'Sweet Spring'. In conclusion, it was demonstrated that 'Nishiuchi Konatsu' has two agriculturally important traits: self-compatibility and seed abortion. It can be useful for elucidating the mechanisms and as the genetic resources that introduce these traits.