Shy Girl, a kiwifruit suppressor of feminization, restricts gynoecium development via regulation of cytokinin metabolism and signalling.

Kiwifruit (Actinidia chinensis) is a dioecious, long-living woody perennial vine. Reduced generation time and induction of hermaphroditism can accelerate crop improvement and facilitate alternative farming for better food security in the face of climate change. Previous studies identified that CENTRORADIALIS genes CEN and CEN4 act to repress flowering, whilst the male-specific Shy Girl (SyGl) gene with homology to type-C cytokinin response regulators could repress gynoecium development in model plants.

Two Y-chromosome-encoded genes determine sex in kiwifruit.

Dioecy, the presence of male and female individuals, has evolved independently in multiple flowering plant lineages. Although theoretical models for the evolution of dioecy, such as the 'two-mutations' model, are well established, little is known about the specific genes determining sex and their evolutionary history. Kiwifruit, a major tree crop consumed worldwide, is a dioecious species.