Disruption of the rice 4-DEOXYOROBANCHOL HYDROXYLASE unravels specific functions of canonical strigolactones

Chen, G.-T. E.; Wang, J. Y.; Votta, C.; Braguy, J.; Jamil, M.; Kirschner, G.; Fiorilli, V.; Berqdar, L.; Balakrishna, A.; Blilou, I.; Lanfranco, L.; Al-Babili, S.

doi:10.1101/2023.04.03.535333

bioRxiv · 10.1101/2023.04.03.535333

Disruption of the rice 4-DEOXYOROBANCHOL HYDROXYLASE unravels specific functions of canonical strigolactones

Chen, G.-T. E.·Wang, J. Y.·Votta, C.·Braguy, J.·Jamil, M.·Kirschner, G.·Fiorilli, V.·Berqdar, L.·Balakrishna, A.·Blilou, I.·Lanfranco, L.·Al-Babili, S.

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Abstract

Strigolactones (SLs) regulate many developmental processes, including shoot-branching/tillering, and mediate rhizospheric interactions. SLs are structurally diverse, divided into a canonical and a non-canonical sub-family. To better understand the biological function of particular SLs, we generated CRISPR/Cas9 mutants disrupted in OsMAX1-1400 or OsMAX1-1900, which encode cytochrome P450 enzymes (CYP711A clade) contributing to SL diversity. The disruption of OsMAX1-1900 did neither affect the SL pattern nor plant architecture, indicating a functional redundancy. In contrast, disruption of OsMAX1-1400 activity, a 4-deoxyorobanchol hydroxylase, led to a complete lack of orobanchol and an accumulation of its precursor 4-deoxyorobanchol (4DO), both of which are a canonical SLs common in different plant species, accompanied by higher levels of the non-canonical methyl 4-oxo-carlactonoate (4-oxo-MeCLA). Os1400 mutants showed also shorter plant height, panicle and panicle base length, but did not exhibit a tillering phenotype. Hormone quantification and transcriptome analysis revealed elevated auxin levels and changes in the expression of auxin-related, as well as of SL biosynthetic genes. Interestingly, the Os900/1400 double mutant lacking both orobanchol and 4DO did not show the observed Os1400 architectural phenotypes, indicating that they are a result of 4DO accumulation. A comparison of the mycorrhization and Striga seed germinating activity of Os900, Os900/1400, and Os1400 loss-of-function mutants demonstrates that the germination activity positively correlates with 4DO content while disrupting OsMAX1-1400 negatively impact mycorrhizal symbiosis. Taken together, our paper deciphers the biological function of canonical SLs in rice and depicts their particular contributions to establishing architecture and rhizospheric communications.

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Chen, G.-T. E., Wang, J. Y., Votta, C., Braguy, J., Jamil, M., Kirschner, G., Fiorilli, V., Berqdar, L., Balakrishna, A., Blilou, I., Lanfranco, L., Al-Babili, S.. 2023-04-04. Disruption of the rice 4-DEOXYOROBANCHOL HYDROXYLASE unravels specific functions of canonical strigolactones. https://doi.org/10.1101/2023.04.03.535333

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