Mitochondrial invertase that cleaves sucrose into glucose and fructose and is involved in the regulation of multiple tissue development and floral transition. May generate glucose as a substrate for mitochondria-associated hexokinase, contributing to mitochondrial reactive oxygen species homeostasis. Hydrolysis of terminal non-reducing beta-D-fructofuranoside residues in beta-D-fructofuranosides. Optimum pH is 9.5. Expressed in seedlings, roots and flowers. By hydrogen peroxide (H(2)O(2)). Reduced primary root length and number of lateral roots. Reduced plant growth, delayed flowering, increased expression of antioxidant genes under basal conditions and reduced oxygen consumption in the dark. Belongs to the glycosyl hydrolase 100 family.