Expression analysis of three h-type thioredoxin isoforms in three Iranian grape (Vitis vinifera L.) cultivars, indicating differential expression in different tissues

Thioredoxins (Trxs) are small ubiquitous disulfide reductases that participate in dithiol-disulfide exchange reactions. In contrast to animals and prokaryotes that typically possess one or a few genes encoding Trxs, higher plants contain eight different Trx types: f, m, x, y, z, o, s, and h. Trx h with multiple forms is involved in different processes such as seed germination, cellular protection against oxidative stress, self-incompatibility etc. The expression analysis of the three h-type Trx genes, called VvTrx h1, VvTrx h2 and VvCxxS2 was studied in different tissues of three grape cultivars (Askari, Red Seedless and White Seedless) at various develpmental stages by semiquantitative reverse transcription polymerase chain reaction (RT-PCR). The grape Trx h genes were expressed in berry, leaf, petiole, cluster, stem, root, and seed tissues at different developmental stages. The higher expression of the isoforms was observed in berry tissues as compared to those of the roots. In berry tissues, the expression of VvTrx h1, VvTrx h2 and VvCxxS2 isoforms were analyzed at six growth stages, including 14, 28, 42, 56, 82, and 110 days post anthesis (dpa). The highest level of expression was observed at veraison stage (56 dpa). The expression of grape Trx h genes was also analyzed in leaf, petiole and cluster tissues at three developmental stages including young, mid and old stages with a imprecise pattern of expression in comparison to the berry tissues. In contrast to VvTrx h1 and VvCxxS2 isoforms, VvTrx h2 showed the highest level of expression in different tissues, suggesting a major role for this isoform in grape.