Changes in Ascorbate Content and the Expression Pattern of Ascorbate Metabolism Genes in Garlic Allium sativum L. Leaves in Response to Cold Stress

In two winter garlic (Allium sativum L.) cultivars, the expression of genes encoding key enzymes of the L-galactose pathway of ascorbate (AsA) biosynthesis (VTC2, GPP, GalDH, GalLDH) and genes encoding AsA recycling from oxidized forms (MDHAR1, MDHAR4, MDHAR5) was determined in the dynamics (0, 2, 4, 6, and 24 h) of short-term (24 h) cold (2 degrees C) stress. It was found that in the leaves of both cultivars (Sarmat and Dubkovsky), the level of VTC2 transcripts steadily increased during stress. The cultivars were also similar in the GalLDH and MDHAR1 expression response to stress, but differed in the reaction of the GPP, GalDH, MDHAR4, and MDHAR5. In the leaves of both cultivars, the content of AsA, carotenoids (total) and chlorophylls (a and b) was determined in the dynamics of cold stress. It was shown that the amount of all analyzed metabolites is initially higher in the cv. Sarmat than in the cv. Dubkovsky, with changes in the stress dynamics in a cultivar-specific manner. A positive correlation was shown between the amount of AsA and the level of expression of the GalDH gene for both cultivars.