Hermaphroditism in Kiwifruit (Actinidia deliciosa): A Review

Abstract

Actinidia, the kiwifruit is approximately 20 to 26 million years old. It is known widely for its dioecious nature; hermaphroditism has also been found to exist in its male inconstant type. Floral development in this plant species progresses through seven unique stages, following the conventional (A) BCE floral model. Male parts of the flower develop early during the third stage, whereas, the degeneration of these parts (pollens) in female plants occurs during later stages owing to programmed cell death. After exploring the sex-linked segment of the kiwifruit genome, the researchers have determined that the Y-encoded sex-determinant genes Shy Girl (SyGl) and Friendly Boy (FrBy) act independently as the suppressors of feminization and promoters of male factors, respectively. Non-expression of SyGl in males results in the formation of hermaphrodites; yet, masculine behaviour has been reported to develop in this fruit crop with plunking of FrBy gene into the female plants. These findings have created new avenues for generating horticulturally important self-pollinating hermaphrodite vines, eliminating the need to waste orchard space on non-fruiting male varieties.