Isolation and characterisation of a UDP-glucose pyrophosphorylase gene associated with fruit ripening in autumn olive (Elaeagnus umbellata Thunb.)

Abstract

SummaryAutumn olive (Elaeagnus umbellata Thunb.) fruit are a rich source of many health-related nutrients. Sweetness is one of the key indicators of quality in this edible fruit. A full-length cDNA for UDP-glucose pyrophosphorylase, an enzyme involved in sugar metabolism, designated EutUGP, was cloned from autumn olive fruit. The open reading frame of EutUGP was 1,431 bp in length, and was interrupted by 18 introns. It encoded a putative polypeptide of 476 amino acids which shared high homology (85 – 87%) with other plant UGPs. The EutUGP gene was highly expressed in fruit and in young stems, but had low levels of expression in roots and leaves. Transcription of EutUGP was up-regulated and reached its maximum in Stage C (dark-yellow) fruit, then decreased slightly in Stage D (full-ripe) fruit. The highest level of accumulation of the EutUGP protein occurred at the full-ripe Stage D. The 953 bp promoter region of the EutUGP gene was isolated using PCR-based DNA-walking. Characterisation of the EutUGP gene and its promoter will contribute to our understanding of its function during ripening in autumn olive fruit.