Abstract:

The AP2/ERF family of transcription factors is involved in the regulation of plant responses to biotic and abiotic stresses. Previously, we cloned LuWRI1a, a WRINKLED1 homologous gene from flax. Protein sequence analysis showed that LuWRI1a contained two AP2 DNA-binding domains and belonged to the AP2/ERF transcription factor family. The cis-acting elements of LuWRI1a were analyzed that pLuWRI1a was found to contain multiple abiotic stress elements in response to light, drought, low temperature and hormones. In this study, the flax cultivar Longya 10 and LuWRI1a overexpression transgenic pure lines were used as the experimental materials, and salt stress and drought stress treatments were simulated with 200 mmol L^-1NaCl nutrient solution and 25% PEG nutrient solution. The results showed that the relative plant height, primary root length, lateral root number, and leaf number of transgenic plants were elevated after salt and drought stress treatments. The activities of three antioxidant enzymes were significantly higher than the control, while MDA content was lower. The relative expression levels of the abiotic stress-responsive genes, LuAREB, LuDREB, LuLEA, and LuNCED, were up-regulated. By exploring the biological function of LuWRI1a under adversity stress, it was found that LuWRI1a enhanced flax tolerance by resisting the inhibition of flax growth by salt stress and drought stress, enhancing the scavenging ability of reactive oxygen species, reducing the oxidative damage of membrane lipids, and activating the expression of adversity stress response genes. In summary, LuWRI1a may be a multifunctional gene, which was not only involved in fatty acid synthesis and metabolism pathway, but also may be involved in plant abiotic stress signaling pathway. This study provides a new genetic resource for the improvement of stress-tolerant varieties of flax.

Key words: flax, LuWRI1a, salt stress, drought stress, functional analysis