Effect of NaCl on Overcoming Self-Incompatibility in Non-Heading Chinese Cabbage (Brassica campestris ssp chinensis Makino) Studied by Fluorescent Microscopy

It had been shown that self-incompatibility could be overcome by NaCl in the self-incompatible Chinese cabbage. In this study, fluorescence microscopy was used to study the stigma and the pollen growth on the stigma after NaCl treatment of non-heading Chinese cabbage flowers. Without NaCl treatment, most pollen grains failed to attach to the stigma and did not germinate in self-incompatible plants, and serious callous reaction of stigma surface prevented pollen tubes from penetrating and gave rise to distorting pollen tubes even if some pollen germinated. While spraying NaCl solution on the stigma surface before self-pollination at anthesis, more pollen grains attached to the stigma and more pollen grains germinated, pollen tubes entered and further penetrated into the stigma. The effectiveness of NaCl was further identified in the field by determining seed setting rate. Results showed that NaCl is very effective in overcoming self-incompatibility in non-heading Chinese cabbage and fluorescence microscopy is an efficient and convenient method to identify self-incompatibility.