Fig. 6. Model shows how auxin affects the gynoecium morphogenesis in papaya.

a 1. Optimal level of auxin is critical for functional gynoecium development 2. Auxin transport inhibitor (NPA) treatment to male flower resulted in polar auxin flow weakening that might drop the auxin concentration to critical level for functional gynoecium development and result in sex reversal from male flower to perfect hermaphrodite flower 3. NPA application to female flower resulted in critically low auxin concentration with the development of stalk-like gynoecium structure (non-functional) completely different from rudimentary gynoecium 4 & 5. A smaller increase in auxin concentration under auxin analogs application resulted in no changes in both male and female flowers. b Hermaphrodite flowers are easily influenced by environment (temperature) comparing to both male and female 1. In summer, increased temperature may result in increased auxin level with the development of rudimentary gynoecium 2. While, in autumn, decrease in temperature may cause the development of functional gynoecium due to drop in auxin level to the critical level for functional gynoecium development