Comparative expression analysis of five WRKY genes from Tibetan hulless barley under various abiotic stresses between drought-resistant and sensitive genotype

Tibetan hulless barley (Hordeum vulgare subsp. vulgare) is exposed to harsh environmental factors, such as drought, salinity, and cold. To explore useful transcription factor genes that could improve stress resistance of Tibetan hulless barley varieties, five WRKY genes were isolated from drought tolerance Tibetan hulless barley genotype TR1, namely, HvvWRKY2, HvvWRKY5, HvvWRKY10, HvvWRKY19, and HvvWRKY46. The HvvWRKY46 belongs to Group I of the WRKY superfamily, whereas the remaining four belong to Group II. All of them were localized to the nucleus of onion epidermal cells. The respective expression of the five WRKY genes was compared under drought, salt, and cold stress in resistant genotype TR1 and sensitive genotype TS1. Among the five, HvvWRKY2, HvvWRKY5, HvvWRKY19, and HvvWRKY46 were induced by drought or PEG6000 stress in TR1 but not in TS1, suggesting that these four WRKY genes are involved in drought resistance. HvvWRKY2 was induced by salt stress in TR1 but not in TS1, indicating that HvvWRKY2 may be involved in salt resistance. What's more, HvvWRKY2 were notably up-regulated in TR1 under cold stress, whereas it was only induced at low level in TS1, indicating that HvvWRKY2 may also participate in cold tolerance.