Zm PBF and Zm GAMYB transcription factors independently transactivate the promoter of the maize ( Zea mays ) β‐carotene hydroxylase 2 gene
2018; Wiley; Volume: 222; Issue: 2 Linguagem: Inglês
10.1111/nph.15614
ISSN1469-8137
AutoresXin Jin, Chao Bai, Ludovic Bassié, C. Nogareda, I. Romagosa, Richard M. Twyman, Paul Christou, Changfu Zhu,
Tópico(s)Plant biochemistry and biosynthesis
ResumoSummary The maize ( Zea mays ) enzyme β‐carotene hydroxylase 2 (Zm BCH 2) controls key steps in the conversion of β‐carotene to zeaxanthin in the endosperm. The Zm BCH 2 gene has an endosperm‐preferred and developmentally regulated expression profile, but the detailed regulatory mechanism is unknown. To gain insight into the regulation of Zm BCH 2 , we isolated 2036 bp of the 5′‐flanking region containing the 263 bp 5′‐untranslated region (5′‐ UTR ) including the first intron. We linked this to the β‐glucuronidase reporter gene gusA . We found that high‐level expression of gusA in rice seeds requires the 5′‐ UTR for enhanced activation. Truncated variants of the Zm BCH 2 promoter retained their seed‐preferred expression profile as long as a prolamin box and AACA motif were present. We identified candidate genes encoding the corresponding transcription factors (Zm PBF and Zm GAMYB ) and confirmed that their spatiotemporal expression profiles are similar to Zm BCH 2 . Both Zm PBF and Zm GAMYB can transactivate Zm BCH 2 expression in maize endosperm. To eliminate potential confounding effects in maize, we characterized the regulation of the minimal promoter region of Zm BCH 2 in transgenic rice. This revealed that Zm PBF and Zm GAMYB independently transactivate the Zm BCH 2 promoter. The mechanism that underpins our data provides an exciting new strategy for the control of target gene expression in engineered plants.
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