Identification and characterization of invertase family genes reveal their roles in vacuolar sucrose metabolism during Pyrus bretschneideri Rehd. fruit development.

23 invertase (PbrInvs) genes, including eight vacuolar invertases (PbrvacInvs), five cell wall invertases (PbrcwInvs) and 10 alkaline/neutral invertases (PbrA/N-Invs), were identified from P. bretschneideri Rehd. genome, with diverse chromosome locations, cis-acting elements, gene structures and motifs. Their expression profiles were tissue-specific, and postharvest light or temperature treatment would alter their expression profiles. During 'Dangshansuli' pear development, in association with visual/inner quality change was the alternations of invertase activity and the expression profiles of PbrInvs. In combination with results of subcellular sugar distribution as well as correlation analysis among sugar content, invertase activity and PbrInv mRNA abundance, PbrvacInv1 might be involved in sucrose decomposition during pear development. PbrvacInv1-GFP fusion protein mainly accumulated on the tonoplast (vacuolar membrane); meanwhile, transient overexpression of PbrvacInv1 in pear fruit would upregulate vacInv activity, causing higher fructose and lower sucrose when compared with that of the control. Furthermore, invertase inhibitor 5 (PbrInvInh5) could interact with PbrvacInv1.