Arabidopsis PDK1-AGC1.5 kinases are crucial for pollen dormancy by promoting JINGUBANG expression and inhibiting jasmonic acid biosynthesis.

The ability to make a timely decision between being dormant and germinating is critical for pollen to achieve a selection advantage. Genetic pathways controlling developmental and environmental-controlled pollen dormancy remain largely unclear. We report here that four Arabidopsis AGC kinases, PDK1.1/PDK1.2 and AGC1.5/AGC1.7, form a kinase cascade to maintain pollen dormancy. Both agc1.5 agc1.7 and pdk1.1 pdk1.2 show precocious pollen germination; the role of AGC1.5 and 3-phosphoinositide-dependent protein kinase-1 (PDK1) in pollen dormancy depends on their kinase activity. By pharmacological, molecular, and genetic approaches, we demonstrate that AGC1.5 kinases mediate JINGUBANG (JGB)-dependent inhibition of jasmonic acid biosynthesis. Functional loss of the genetic pathway, that is in the pdk1.1 pdk1.2 or agc1.5 agc1.7 double mutants, results in hypersensitivity to high humidity. Results presented uncover a PDK1-AGC1.5-JGB module mediating developmental and environmental-controlled pollen dormancy.