Required for acclimation to reactive oxygen species (ROS) responses downstream of beta-cyclocitral (beta-cc) or mediated by dihydroactinidiolide, including singlet oxygen 1O(2) detoxification reactions, especially upon light-mediated photooxidative stress, and leading to programmed cell death (PubMed:24151292, PubMed:27813110). Prevents leaf senescence (PubMed:24151292). Involved in cold acclimation (PubMed:27813110). Moves from homogeneous distribution in the cytosol to discrete spots (e.g. stress granules (SGs) and processing bodies (PBs)) in response to singlet oxygen 1O(2) exposure (PubMed:24151292). Accumulates in nucleus after beta-cyclocitral (beta-cc) treatment (PubMed:27813110). Mainly expressed in the epidermis. By high light (PubMed:24151292). Triggered by the carotenoid metabolite beta-cyclocitral (beta-cc) (PubMed:27813110). Normal plants under standard growth conditions, but severe symptoms of photooxidative damage under excess light due to a deficient induction of singlet oxygen 1O(2) detoxification reactions, thus leading to pale leaf phenotype, early senescence and lack of anthocyanin accumulation (PubMed:24151292, PubMed:27813110). Increased susceptibility to low temperatures and high photon flux density (PFD) conditions. Increased lipid peroxidation in response to beta-cyclocitral (beta-cc) associated with reduced induction of reactive oxygen species (ROS) responsive genes (e.g. AAA, LTI30, ZAT12 and WRKY40). Altered induction of gene (e.g. AAA, OXI1, CAT2, APX1 and RD20) expression in response to the lactone dihydroactinidiolide (PubMed:27813110). Accumulation of singlet oxygen 1O(2) in chloroplasts in response to light stress. Early senescence of the older leaves. Plants lacking both MBS1 and MBS2 exhibit premature leaf senescence (PubMed:24151292).