Close arrangement of CARK3 and PMEIL affects ABA-mediated pollen sterility in Arabidopsis thaliana.

Abscisic acid (ABA) signaling is a vital plant signaling pathway for plant responses to stress conditions. ABA treatment can alter global gene expression patterns and cause significant phenotypic changes. We investigated the responses to ABA treatment during flowering in Arabidopsis thaliana. Dipping the flowers of CARK3 T-DNA mutants in ABA solution, led to less reduction of pollen fertility than in the wild type plants (Col-0). We demonstrated that PMEIL, a gene located downstream of CARK3, directly affects pollen fertility. Due to the close arrangement of CARK3 and PMEIL, CARK3 expression represses transcription of PMEIL in an ABA-dependent manner through transcriptional interference. Our study uncovers a molecular mechanism underlying ABA-mediated pollen sterility and provides an example of how transcriptional interference caused by close arrangement of genes may mediate stress responses during plant reproduction.