Tocopherols are
antioxidants found in chloroplasts of leaves, and it is a matter of current debate whether or not they can affect signaling and gene expression in plant cells. For insight into the possible effects of altered
tocopherol composition in chloroplasts on gene expression in the nucleus, the expression of
ethylene biosynthesis, perception and signaling genes was investigated in vte1 and vte4 Arabidopsis thaliana mutants, which are impaired in
tocopherol (
vitamin E) biosynthesis. Changes in gene expression were measured in plants exposed to either
salt or
water stress, and in young and mature leaves of vte1 and vte4 mutants, which lack
tocopherol cyclase and γ-
tocopherol methyltransferase, respectively. While transcript levels of
ethylene signaling genes in the vte1 mutant and the wild type were similar in all tested conditions, major changes in gene expression occurred in the vte4 mutant, particularly in mature leaves (compared with young leaves) and under salt stress. Accumulation of γ- instead of α-
tocopherol in this mutant led to elevated transcript levels of
ethylene signaling pathway genes (particularly CTR1, EIN2, EIN3 and ERF1) in mature leaves of control plants. However, with
salt treatment, transcript levels of most of these genes remained constant or dropped in the vte4 mutant, while they were dramatically induced in the wild type and the vte1 mutant. Furthermore, under salt stress, leaf age-induced
jasmonic acid accumulated in both the vte1 mutant and the wild type, but not in the vte4 mutant. It is concluded that
jasmonic acid and
ethylene signaling pathways are down-regulated in mature leaves of
salt-stressed vte4 plants.