HVA1, a LEA gene from barley confers dehydration tolerance in transgenic rice (Oryza sativa L.) via cell membrane protection

Drought is by far the leading environmental stress-limiting crop yields world-wide. Genetic engineering techniques hold great promise for developing crop cultivars with drought tolerance. Transgenic rice plants have been developed by engineering a wide variety of genes and were shown to be drought tolerant. Understanding the mechanism of stress tolerance in these transgenic plants under agronomically realistic stress conditions would further hasten breeding for drought resistance in rice. In this study, transgenic rice lines expressing the barley HVAJ gene were tested under prolonged drought stress cycle to understand the mechanism of dehydration tolerance. Transgenic plants maintained higher leaf relative water content (RWC) and showed lesser reduction in plant growth under drought stress as compared to non-transgenic (NT) plants. Maintenance of higher plant water status delayed wilting by more than 2 weeks in transgenic plants as compared to NT plants. Transgenic lines had relatively better cell membrane protection than NT line 28 days after stress. Both transgenic and NT lines had similar but low levels of osmotic adjustment (OA) under drought stress. The results indicated that the production of HVA1 proteins might have helped in better performance of transgenic rice plants by protecting cell membrane from injury under drought stress. (C) 2003 Elsevier Ireland Ltd. All rights reserved.