Invertases are key
enzymes for
carbon metabolism, cleaving
sucrose into energy-rich and signaling metabolites,
glucose and
fructose. Invertases play pivotal roles in development and stress response, determining yield and quality of seed production. In this context, the repertoire of
invertase gene families is critically scarce in legumes. Here, we performed a systematic search for
invertase families in 16 Fabaceae genomes. For instance, we identified 19
invertase genes in the model plant Medicago and 17 accessions in the agronomic crop Pisum sativum. Our comprehensive phylogenetic analysis sets a milestone for the scientific community as we propose a new nomenclature to correctly name plant invertases. Thus, neutral invertases were classified into four clades of cytosolic
invertase (CINV).
Acid invertases were classified into two cell wall
invertase clades (CWINV) and two vacuolar
invertase clades (VINV). Then, we explored transcriptional regulation of the pea
invertase family, focusing on seed development and
water stress.
Invertase expression decreased sharply from embryogenesis to seed-filling stages, consistent with higher
sucrose and lower
monosaccharide contents. The vacuolar
invertase PsVINV1.1 clearly marked the transition between both developmental stages. We hypothesize that the predominantly expressed cell wall
invertase, PsCWINV1.2, may drive
sucrose unloading towards developing seeds. The same candidates, PsVINV1.1 and PsCWINV1.2, were also regulated by water deficit during embryonic stage. We suggest that PsVINV1.1 along with vacuolar
sugar transporters maintain cellular osmotic pressure and PsCWINV1.2 control
hexose provision, thereby ensuring embryo survival in drought conditions. Altogether, our findings provide novel insights into the regulation of plant
carbon metabolism in a challenging environment.