Cell wall-associated invertase that cleaves sucrose into glucose and fructose and is required for assimilated carbon partitioning during early grain-filling. May be involved in sucrose unloaded in the ovular and stylar vascular tissues for the stimulation of starch synthesis in the developing endosperm during grain-filling (PubMed:18820698). Sugar homeostasis mediated by CIN2/GIF1 plays an important role in constitutive and induced physical and chemical defense against pathogens (PubMed:24118770). Hydrolysis of terminal non-reducing beta-D-fructofuranoside residues in beta-D-fructofuranosides. Associated with the cell wall. Expressed in leaves and flowers. Weakly expressed in seeds (PubMed:15759120). Expressed in growing roots, node and the rapidly elongating zone of the internode (PubMed:18820698). Expressed throughout flowering, with higher expression from 1 to 6 days after flowering (PubMed:15759120). During early grain-filling, expressed in the ovular vascular and lateral stylar vascular traces (PubMed:18820698). By sucrose in caryopsis from 1 to 2 and from 9 to 10 days after flowering. Slow grain-filling resulting in reduced weight of grains containinf loosely packed starch granules and reduced levels of amylose and amylopectin. CIN2/GIF1 is a potential domestication-selected gene that controls grain filling and yield, and could be used for further crop improvement. Belongs to the glycosyl hydrolase 32 family.