Ammopiptanthus mongolicus stress-responsive NAC gene enhances the tolerance of transgenic Arabidopsis thaliana to drought and cold stresses.

Drought and cold are the primary factors limiting plant growth worldwide. The Ammopiptanthus mongolicus NAC11 (AmNAC11) gene encodes a stress-responsive transcription factor. Expression of the AmNAC11 gene was induced by drought, cold and high salinity. The AmNAC11 protein was localized in the nucleus and plays an important role in tolerance to drought, cold and salt stresses. We also found that differential expression of AmNAC11 was induced in the early stages of seed germination and was related to root growth. When the AmNAC11 gene was introduced into Arabidopsis thaliana by an Agrobacterium-mediated method, the transgenic lines expressing AmNAC11 displayed significantly enhanced tolerance to drought and freezing stresses compared to wild-type Arabidopsis thaliana plants. These results indicated that over-expression of the AmNAC11 gene in Arabidopsis could significantly enhance its tolerance to drought and freezing stresses. Our study provides a promising approach to improve the tolerance of crop cultivars to abiotic stresses through genetic engineering.

AmDREB2C, from Ammopiptanthus mongolicus, enhances abiotic stress tolerance and regulates fatty acid composition in transgenic Arabidopsis.

Dehydration-responsive element-binding (DREB) transcription factors (TFs) play a vital role in plant response to abiotic stresses. However, little is known about DREB TFs in plants adapted to harsh environments and in the formation of polyunsaturated fatty acids (PUFAs), a major membrane component closely associated with plant stress tolerance. Here, we characterized AmDREB2C in Ammopiptanthus mongolicus (Maxim. ex kom.) Cheng F., a desert evergreen broadleaf shrub with a high tolerance to harsh environments. AmDREB2C encodes a canonical DREB2-type TF, and the protein was localized in the nucleus. AmDREB2C had the highest expression levels in leaves of naturally growing shrubs in the wild during the winter season of a year of sampling. The expression was also induced by cold, heat and drought stresses in laboratory-cultured seedlings. Moreover, AmDREB2C was most abundantly expressed in young leaves and immature seeds rather than other tissues of the shrubs. Constitutive expression of AmDREB2C in Arabidopsis enhanced freezing, heat and drought tolerances of the transgenic plants, likely through inducing the expression of important stress-responsive genes. The transgene also increased the level of linolenic acid (C18:3), a major PUFA in most plant species, in leaves and seeds of the transgenic plants. Correspondingly, the transcription of FAD3, FAD7 and FAD8, three genes encoding fatty acid desaturases (FADs) responsible for the production of C18:3, showed a differential up-regulation in these two organs. This study provides new insight into the underlying molecular mechanisms of A. mongolicus' ability to endure harsh environments and DREB TF regulation of fatty acid desaturation.