PSG076 Promoter Shows Late Pollen-Specific Activity in Wheat ( Triticum aestivum L.)

Pollen, as the male gametophyte of plants, plays a critical role in plant sexual reproduction. Investigating pollen-specific promoters not only helps to understand the regulatory mechanisms of pollen development but also provides tissue-specific promoters for plant genetic engineering. Previously, wheat promoter PSG076 was found to confer pollen-specific activity in tobacco. To determine the tissue-specific activity of PSG076 in wheat, a 1.4-kb promoter fragment was fused with the β-glucuronidase (GUS) reporter gene and stably introduced into wheat via particle bombardment. Histochemical analysis in T 1 progeny plants showed that the activity of PSG076 promoter was detected specifically in mature pollen and pollen tube. No GUS activity was found in other floral and vegetable tissues. Weak GUS staining was also visible in pollen at 45 days post anthesis (DPA). Further analysis showed that GUS activity was found weakly in middle tricellular pollen grains and increased rapidly as pollen matured. These results indicated that PSG076 promoter has strong activity specifically at late pollen development stage and can be utilized in genetic engineering investigations for creating male sterility in wheat and other plant species for hybrid seed production.