2.7.7.69 malfunction antisense transgenic tomato plants with about 50% decrease in ascorbate (AsA) content are obtained in order to investigate the role of GGP against chilling stress. The suppression of SlGGP could decrease ascorbate levels and enhance plant sensitivity to chilling stress-induced oxidative stresses 725801 2.7.7.69 malfunction ascorbate concentrations are negligible in both null segregant (NS) and 35S-OsGGP brown rice (BR, unpolished grain), but significantly increased in 35S-OsGGP germinated brown rice (GBR) relative to NS. Foliar ascorbate concentrations are significantly increased in 35S-OsGGP plants in the vegetative growth phase relative to NS, but significantly reduced at the reproductive growth phase and are associated with reduced OsGGP transcript levels. The 35S-OsGGP plants do not display altered salt tolerance at the vegetative growth phase despite having elevated ascorbate concentrations 761175 2.7.7.69 malfunction deficiency of GDP-L-galactose phosphorylase reduces tomato fruit yield, the whole fruit biomass accumulation is reduced in mutant lines. The SlGGP1 mutants display decreased concentrations of ascorbate in roots, leaves, flowers, and fruit. The initiation of anthesis is delayed in ggp1 plants but the number of flowers is similar to wild type. The number of fruits is reduced in ggp1 mutants with an increased individual weight. Ethylene production is higher in the mutant lines than wild-type fruit at the breaker and red stages. Effects of source-sink manipulation on fruit yield characteristics, overview 762186 2.7.7.69 malfunction the VTC2 amiRNA lines grow more slowly, have lower chlorophyll content, and are more susceptible to stress than the control strains. Ascorbate concentrations in VTC2 amiRNA lines are reduced to 10% of wild-type level. In the VTC2 amiRNA lines, the mRNA abundances of APX1 and DHAR1, the main chloroplastic forms, are about 40% lower than in the EV2 control -, 762022 2.7.7.69 metabolism Chlamydomonas VTC2 lacks negative feedback regulation by ascorbate in the physiological concentration range. Ascorbate biosynthesis is also highly regulated in Chlamydomonas albeit via mechanisms distinct from those described in land plants. Dependence of Asc biosynthesis on the photosynthetic electron transport chain -, 762022 2.7.7.69 metabolism GDP-L-galactose phosphorylase (GGP) catalyzes the first step committed to ascorbic acid synthesis. The ascorbate biosynthetic pathway critically participates in tomato development and fruit production 762186 2.7.7.69 metabolism GDP-L-galactose phosphorylase is the rate-limiting enzyme of the L-galactose pathway 761175 2.7.7.69 physiological function GDP-L-galactose phosphorylase is required for ascorbic acid synthesis. Participation of GDP-L-galactose phosphorylase and ascorbate in tomato fruit production and quality 762186 2.7.7.69 physiological function GDP-L-galactose phosphorylase plays a pivotal role in ascorbate biosynthesis. In contrast to plants, there is no circadian regulation of ascorbate biosynthesis, photosynthesis is not required per se for ascorbate biosynthesis, and Chlamydomonas VTC2 lacks negative feedback regulation by ascorbate in the physiological concentration range -, 762022 2.7.7.69 physiological function GGP has a critical role in modulating ascorbate concentrations in kiwifruit species under abiotic stresses 739380