CYP72A enzymes catalyse 13-hydrolyzation of gibberellins

Abstract

Bioactive gibberellins (GAs, diterpenes) are essential hormones in land plants, controlling many aspects of plant growth and developments. In flowering plants, 13-OH (low bioactivity; such as GA1) and 13-H GAs (high bioactivity; such as GA4) frequently coexist. However, the bona fide GA 13-hydroxylase and its physiological functions in Arabidopsis remain unknown. Here, we report that novel cytochrome P450 genes (CYP72A9 and its homologs) encode active GA 13-hydroxylases in Brassicaceae plants. CYP72A9-overexpressing plants exhibited semi-dwarfism, which was caused by significant reduction in GA4 levels. Biochemical assays revealed that recombinant CYP72A9 protein catalyzed the conversion from 13-H GAs to the corresponding 13-OH GAs. CYP72A9 was expressed predominantly in developing seeds in Arabidopsis. Freshly harvested seeds of cyp72a9 mutants germinated more quickly than wild-type, while long-term storage and stratification-treated seeds did not. The evolutionary origin of GA 13-oxidases from the CYP72A subfamily also was investigated and discussed here.

Gibberellin metabolism and signaling and its molecular mechanism in regulating seed germination and dormancy

“…[30] . 最近, He等人 [37] 发现, CYP72A9编码GA 13-氧化酶, 该酶催化13-H [38] . 研究人员已经在 拟南芥中发现了5个GA20ox [39] 和4个GA3ox [40] 基因, 然 而仅在AtGA20ox1(ga5)和AtGA3ox1(ga4)突变体中观 察到半矮化的生长表型 [41] .…”

FIS1 encodes a GA2-oxidase that regulates fruit firmness in tomato

“…GA analysis was performed on a quadrupole linear ion trap hybrid mass spectrometer (QTRAP 6500, AB) equipped with an electrospray ionization (ESI) source coupled with a UPLC (Waters). The UPLC inlet method and ESI source parameters were set as in a previous report 51 . GAs were detected in negative multiple reaction monitoring (MRM) mode.…”

Gibberellin Metabolism in Flowering Plants: An Update and Perspectives

“…More recently, CYP72A9 (encoded by At3g14630) was reported to catalyze the 13-H GAs (GA 12 , GA 9 , GA 4 ) into 13-OH GAs (GA 53 , GA 20 , GA 1 ), which is inconsistent with the traditional view that GA 4 and GA 1 are biosynthesized in parallel by GA20ox and GA3ox in flowering plants, from GA 12 and GA 53 , respectively (Figure 1; He et al, 2019). It was unexpected to discover that CYP72A9 encoded GA 13-hydroxylase, as CYP72A9 FIGURE 1 | Simplified GA metabolic pathway in flowering plants.…”

“…Moreover, CYP72A9 was expressed predominantly in developing seeds in Arabidopsis, and cyp72a9 mutants showed a deficiency of GA 1 but an increase of GA 4 in the siliques. CYP72A9 was further proven to be involved in primary seed dormancy (He et al, 2019). The other three Arabidopsis CYP72A members (A7, A13, and A15) also showed GA 13-hydroxylase activity, but overexpression plants did not show a semi-dwarf phenotype, which merits further investigation of the physiological functions of these genes in planta.…”

“…The other three Arabidopsis CYP72A members (A7, A13, and A15) also showed GA 13-hydroxylase activity, but overexpression plants did not show a semi-dwarf phenotype, which merits further investigation of the physiological functions of these genes in planta. Homologs of CYP72A9 in other Brassicaceae plants, such as CYP72A262 in Brassica rapa and CYP72A484 in Capsella rubella, also have GA 13-hydroxylase activity, although with slightly different substrate preferences (He et al, 2019). It appears that the recruitment of GA deactivation enzymes shows different tissue specificity in different plant species, at least at the family level: CYP714D1 and CYP714B1/B2 are highly expressed in the uppermost internode of rice (Poaceae family), while all GA deactivation genes (CYP72A9, GAMT1/2, and CYP714A1/A2) are predominantly expressed in the developing siliques/seeds of Arabidopsis (Brassicaceae family).…”