Insights into transcriptional regulation of ?-D-N-acetylhexosaminidase, an N-glycan-processing enzyme involved in ripening-associated fruit softening.

ABSTRACT: Tomato (Solanum lycopersicum) fruit ripening-specific N-glycan processing enzyme, ?-D-N-acetylhexosaminidase (?-Hex), plays an important role in the ripening-associated fruit-softening process. However, the regulation of fruit ripening-specific expression of ?-Hex is not well understood. We have identified and functionally characterized the fruit ripening-specific promoter of ?-Hex and provided insights into its transcriptional regulation during fruit ripening. Our results demonstrate that RIPENING INHIBITOR (RIN), a global fruit ripening regulator, and ABSCISIC ACID STRESS RIPENING 1 (SlASR1), a poorly characterized ripening-related protein, are the transcriptional regulators of ?-Hex. Both RIN and SlASR1 directly bound to the ?-Hex promoter fragments containing CArG and C???(C/G)A cis-acting elements, the binding sites for RIN and SlASR1, respectively. Moreover, ?-Hex expression/promoter activity in tomato fruits was downregulated once expression of either RIN or SlASR1 was suppressed; indicating that RIN and SlASR1 positively regulate the transcription of ?-Hex during fruit ripening. Interestingly, RIN could also bind to the SlASR1 promoter, which contains several CArG cis-acting elements, and SlASR1 expression was suppressed in rin mutant fruits, indicating that RIN also acts as a positive regulator of SlASR1 expression during fruit ripening. Taken together, these results suggest that RIN, both directly and indirectly, through SlASR1, regulates the transcription of ?-Hex during fruit ripening. The fruit ripening-specific promoter of ?-Hex could be a useful tool in regulating gene expression during fruit ripening.

SUBMITTER: Irfan M 

PROVIDER: S-EPMC4203122 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature