Details

Autor(en) / Beteiligte

• Zhou, Yuchan
• O'Hare, Tim J.
• Jobin-Decor, Marcelle
• Underhill, Steven J. R.
• Wills, Ron B. H.
• Graham, Michael W.

Titel

Transcriptional regulation of a pineapple polyphenol oxidase gene and its relationship to blackheart

Ist Teil von

• Plant biotechnology journal, 2003-11, Vol.1 (6), p.463-478

Ort / Verlag

Oxford, UK: Blackwell Science Ltd

Erscheinungsjahr

2003

Quelle

Elektronische Zeitschriftenbibliothek - Frei zugängliche E-Journals

Beschreibungen/Notizen

• Summary Two genes encoding polyphenol oxidase (PPO) were isolated from pineapple (Ananas comosus[L.] Merr. cv. Smooth Cayenne). Sequence analyses showed that both contained a single intron and encoded typical chloroplast‐localized PPO proteins, the sequences of which corresponded to two pineapple PPO cDNAs, PINPPO1 and PINPPO2, recently described by Stewart et al. (2001). Southern blot analyses suggested that pineapple contained only two PPO genes. Analysis of expression of PINPPO1 promoter GUS fusion constructs showed this promoter had a low basal activity and was cold‐ and wound‐inducible, consistent with known mRNA expression profiles. Striking homologies to gibberellin response complexes (GARC) were observed in sequences of both the PINPPO1 and PINPPO2 promoters. Transient assays in mature pineapple fruit and stable expression in transgenic tobacco showed that PINPPO1 promoter‐GUS fusions were indeed gibberellin (GA) responsive. A role for the element within the putative GARCs in mediating GA‐responsiveness of the PINPPO1 promoter was confirmed by mutational analysis. PINPPO2 was also shown to be GA‐responsive by RT‐PCR analysis. Mutant PINPPO1 promoter–GUS fusion constructs, which were no longer GA‐inducible, showed a delayed response to cold induction in pineapple fruit in transient assays, suggesting a role for GA in blackheart development. This was supported by observations that exogenous GA3 treatment induced blackheart in the absence of chilling. Sequences showing homology to GARCs are also present in some PPO promoters in tomato, suggesting that GA regulates PPO expression in diverse species.