The Arabidopsis D27like1 is a novel Isomerase that Contributes to SL Biosynthesis and Negatively Impacts ABA Level

Yang, Y.; Abuauf, H.; Song, S.; Wang, J. Y.; Alagoz, Y.; Moreno Beltran, J. C.; Mi, J.; Ablazov, A.; Jamil, M.; Ali, S.; Zheng, X.; Balakrishna, A.; Blilou, I.; Al-Babili, S.

doi:10.1101/2022.06.07.495147

bioRxiv · 10.1101/2022.06.07.495147

The Arabidopsis D27like1 is a novel Isomerase that Contributes to SL Biosynthesis and Negatively Impacts ABA Level

Yang, Y.·Abuauf, H.·Song, S.·Wang, J. Y.·Alagoz, Y.·Moreno Beltran, J. C.·Mi, J.·Ablazov, A.·Jamil, M.·Ali, S.·Zheng, X.·Balakrishna, A.·Blilou, I.·Al-Babili, S.

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Abstract

The enzyme DWARF27 (D27) catalyzes the reversible isomerization of all-trans- into 9-cis-{beta}-carotene, initiating strigolactone (SL) biosynthesis. Genomes of higher plants encode two D27-homologs, D27-like1 and -like2, with unknown functions. Here, we investigated the enzymatic activity and biological function of the Arabidopsis D27-like1. In vitro enzymatic assays and Expression in Synechocystis sp. PCC6803 revealed a yet not reported 13-cis/15-cis/9-cis- and a 9-cis/all-trans-{beta}-carotene isomerization. Although disruption of AtD27-like1 did not cause SL deficiency phenotypes, overexpression of AtD27-like1 in the Atd27 mutant restored the more-branching phenotype, indicating a contribution of AtD27-like1 to SL biosynthesis. Accordingly, generated Atd27 Atd27like1 double mutants showed more pronounced branching phenotype, compared to Atd27. The contribution of AtD27-like1 to SL biosynthesis is likely due to its formation of 9-cis-{beta}-carotene that was present at higher levels in AtD27-like1 overexpressing lines. In contrast, AtD27-like1 expression correlated negatively with the content of 9-cis-violaxanthin, a precursor of abscisic acid (ABA), in shoots. Consistently, ABA levels were higher in shoots and also in dry seeds of the Atd27like1 and Atd27 Atd27like1 mutants. Transgenic lines expressing {beta}-glucuronidase (GUS) driven by the AtD27LIKE1 promoter and transcript analysis performed with hormone-treated Arabidopsis seedlings unraveled that AtD27LIKE1 is expressed in different tissues and regulated ABA and auxin. Taken together, our work revealed a cis/cis-{beta}-carotene isomerase activity that affects the content of both cis-carotenoid derived plant hormones ABA and SLs.

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Yang, Y., Abuauf, H., Song, S., Wang, J. Y., Alagoz, Y., Moreno Beltran, J. C., Mi, J., Ablazov, A., Jamil, M., Ali, S., Zheng, X., Balakrishna, A., Blilou, I., Al-Babili, S.. 2022-06-07. The Arabidopsis D27like1 is a novel Isomerase that Contributes to SL Biosynthesis and Negatively Impacts ABA Level. https://doi.org/10.1101/2022.06.07.495147

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