MYB2 Is Important for Tapetal PCD and Pollen Development by Directly Activating Protease Expression in Arabidopsis

Tapetal programmed cell death (PCD) is a complex biological process that plays an important role in pollen formation and reproduction. Here, we identified the MYB2 transcription factor expressed in the tapetum from stage 5 to stage 11 that was essential for tapetal PCD and pollen development in Arabidopsis thaliana. Downregulation of MYB2 retarded tapetal degeneration, produced defective pollen, and decreased pollen vitality. EMSA and transcriptional activation analysis revealed that MYB2 acted as an upstream activator and directly regulated expression of the proteases CEP1 and βVPE. The expression of these proteases was lower in the buds of the myb2 mutant. Overexpression of either/both CEP1 or/and βVPE proteases partially recover pollen vitality in the myb2 background. Taken together, our results revealed that MYB2 regulates tapetal PCD and pollen development by directly activating expression of the proteases CEP1 and βVPE. Thus, a transcription factor/proteases regulatory and activated cascade was established for tapetal PCD during another development in Arabidopsis thaliana. Highlight: MYB2 is involved in tapetal PCD and pollen development by directly regulating expression of the protease CEP1 and βVPE and establishes a transcription factor/proteases regulatory and activated cascade.