OsPKS2 is required for rice male fertility by participating in pollen wall formation
OsPKS2, the rice orthologous gene of Arabidopsis PKSB/LAP5, encodes a polyketide synthase that is involved in pollen wall formation in rice.
In flowering plants, the pollen wall protects male gametes from various environmental stresses and pathogen attacks, as well as promotes pollen germination. The biosynthesis of sporopollenin in tapetal cell is critical for pollen wall formation. Recently, progress has been made in understanding sporopollenin metabolism during pollen wall development in Arabidopsis. However, little is known about the molecular mechanism that underlies the sporopollenin synthesis in pollen wall formation in rice (Oryza sativa). In this study, we identified that a point mutation in OsPKS2, a plant-specific type III polyketide synthase gene, caused male sterility in rice by affecting the normal progress of pollen wall formation. Two other allelic mutants of OsPKS2 were generated using the CRISPR/Cas9 system and are also completely male sterile. This result thus further confirmed that OsPKS2 controls rice male fertility. We also showed that OsPKS2 is an orthologous gene of Arabidopsis PKSB/LAP5 and has a tapetum-specific expression pattern. In addition, its product localizes in the endoplasmic reticulum. Results suggested that OsPKS2 is critical for pollen wall formation, and plays a conserved but differentiated role in sporopollenin biosynthesis from Arabidopsis.
KeywordsOsPKS2 PKSB/LAP5 Rice Pollen Exine Sporopollenin
This work was supported by the National Natural Science Foundation of China (91435102 and 31570004), the Sichuan provincial founding for Distinguished Young Scholars (2015JQ0048), the Open Research Fund of State Key Laboratory of Hybrid Rice (Hunan Hybrid Rice Research Center, 2016KF10), and the Sichuan Science and Technology Support Project (2016NZ0103).
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Conflict of interest
The authors declare that they have no conflict of interest.
- Daku RM et al. (2016) Ppascl, the physcomitrella patens anther-specific chalcone synthase-like enzyme implicated in sporopollenin biosynthesis, is needed for integrity of the moss spore wall and spore viability. PloS one 11:e0146817. https://doi.org/10.1371/journal.pone.0146817 CrossRefPubMedPubMedCentralGoogle Scholar
- Wallace S et al (2015) Conservation of male sterility 2 function during spore and pollen wall development supports an evolutionarily early recruitment of a core component in the sporopollenin biosynthetic pathway. New Phytol 205:390–401. https://doi.org/10.1111/nph.13012 CrossRefPubMedGoogle Scholar
- Zhang D, Li H (2014) Exine export in pollen. In: Geisler M (ed) Plant abc transporters. Springer, Cham, pp 49–62. https://doi.org/10.1007/978-3-319-06511-3_4Google Scholar