Acid vacuolar invertase 1 (PbrAc-Inv1) and invertase inhibitor 5 (PbrII5) were involved in sucrose hydrolysis during postharvest pear storage

Abstract

In pear, sucrose was mainly distributed in vacuole; and the alternation of sucrose abundance was associated the change of vacuolar invertase (VI) activity during fruit storage. However, the molecular mechanism beneath such phenomenon has not been clarified until recently. For this, a combination of metabolite, enzyme activity, transcriptome, quantitative real-time PCR (qRT-PCR), bioinformation, subcellular localization, and transient overexpression assay was conducted in this study to identify the acid invertase 1 (PbrAc-Inv1) and invertase inhibitor 5 (PbrII5) involved in sucrose degradation during 'Housui' pear storage. Both PbrAc-Inv1 and PbrII5 were located in vacuolar membrane. PbrAc-Inv1 could accelerate sucrose degradation; on the other hand, PbrII5 could bind with PbrAc-Inv1 to form a inactive complex, downregulate the VI activity, and suppressed sucrose decomposition. Based on Bio-layer interferometry (BLI) result after domain substitution, the domain on the left of catalytic 'WEC-P/V-D' box in PbrAc-Inv1 might played a key role in its interaction with PbrII5.

Keywords: Pear fruit; Postharvest storage; Sucrose hydrolysis; Vacuolar invertase; Vacuolar invertase inhibitor.