Identification of potential molecular markers for flower sex determination in Vernicia fordii

Vernicia fordii is cultivated as an important woody oil tree, with a long history in China. It is a monoecious and diclinous species. Altering the sex ratio to increase the number of female flowers would lead to better yields. The mechanism of flower development is, however, not yet clear. In this study, the proteins that are differentially expressed between male and female flowers were isolated using a combination of two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionisation time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF MS). A proteomic analysis led to the identification of 14 proteins, of which two were expressed specifically in male flowers and 10 in female flowers. Among the 10 female-specific proteins, aspartic proteinase, ascorbate peroxidase, and cyclophilin were thought to be involved in stamen abortion and gynoecium formation during the development of female flowers. Further results suggested that these proteins might be the sex-related proteins that are the potential molecular markers for flower sex determination in V. fordii.