A rice exocyst subunit gene SEC3A is required for anther dehiscence

Anther dehiscence controls optimal interaction between pollen and stigma, thereby determining the successful sexual reproduction. The regulators or mechanisms of this process remain elusive. Here, two CRISPR/Cas9 mutants of a rice exocyst subunit gene SEC3A, sec3a-1 and sec3a-2, showed anther indehiscence at anthesis and male sterility at maturity. Pollen viability and germination in the mutants were partly defective, whereas their female gametes undergone a normal development. Hybrid or self-pollinated seeds could be produced by artificial pollination, suggesting potential use of a weak sec3a mutant as a female line during hybrid breeding. SEC3A is widely expressed in various tissues, including anther walls. Further results showed an excessive IAA accumulation and no endothecium lignification in sec3a-1/2 anthers. Our findings suggest that SEC3A appears to regulate anther dehiscence by modulating auxin signaling, providing insights into regulation of anther dehiscence and function of exocyst in plants.