Abstract:

【Objective】Cell wall invertase (CWI) and vacuolar invertase (VI) act as the essential regulators in photosynthate distribution, maintenance of sink strength and stress responses. A large body of evidence prompted that the tight control of CWI and VI substantially subjects to the post-translational mechanisms mediated by small proteinaceous inhibitors (C/VIFs, inhibitor of β-fructosidases). However, the survey of the molecular information and gene transcript abundance, as well as biochemical characteristics of C/VIFs is largely unknown in a woody model plant, black cottonwood (Populus trichocarpa). 【Method】In this work, the bioinformatics and qRT-PCR were performed to analyze the phylogenetic tree and gene tissue-specific expression profiling. The transient and stable transformation systems and enzyme assays were conducted to evaluate the subcellular target and inhibitory function of PtC/VIF1. 【Result】A total of 39 genes encoding C/VIF were identified. PtC/VIF1 showing root-specific expression was characterized and its extracellular localization was verified. Evaluation of the recombinant enzyme suggested that PtC/VIF1 showed patterns of the typical apoplastic invertase inhibitor. 【Conclusion】It is the first report on the functional isolation of the C/VIF in poplar. These results pointed out that PtC/VIF1 may play potential roles in defense- and stress-related responses.

Key words: poplar, β-fructosidases invertase inhibitor;, post-translational regulation mechanism, cell wall invertase and vacuolar invertase, sucrose, apoplast, biotic stress