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Various plant species in the Qinghai-Tibet Plateau exposed to harsh conditions, such as low oxygen, drought, extremely low temperatures and salinity, have evolved both molecular and physiological adaptation strategies to deal with these multiple stresses. Sophora moorcroftiana (Benth.) Baker (Fabaceae) is a highly drought-resistant endemic Sophora shrub species in the Qinghai-Tibet Plateau. In our previous study, a drought-induced DREB transcription factor gene was identified and was designated as SmDREB1. SmDREB1-GFP fusion construct was introduced into Arabidopsis protoplast to characterise the function of SmDREB1 in drought resistance. The results showed that SmDREB1 targets the nucleus of Arabidopsis protoplast. Ectopic expression of SmDREB1 in model plant species Arabidopsis was performed. The transgenic lines showed increasing expressions of drought marker genes including AtDHN, AtLEA, AtPIP2 ;2, AtPIP2;3 and AtRD29, increasing activities of antioxidant enzymes and proline contents and increasing light-use efficiency under drought stress as compared with the wild-type plants; SmDREB1 transgenic lines are more resistant to drought than wild-type plants. Therefore, the SmDREB1 is a drought-resistant transcription factor gene of S. moorcroftiana and could be a candidate in genetic engineering to improve drought resistance of plateau plant species.

Sophora moorcroftiana, a Leguminosae shrub species that is restricted to the arid and semi-arid regions of the Qinghai-Tibet Plateau, is an ecologically important foundation species and exhibits substantial drought tolerance in the Plateau. There are no functional genomics resources in public databases for understanding the molecular mechanism underlying the drought tolerance of S. moorcroftiana. Therefore, we performed a large-scale transcriptome sequencing of this species under drought stress using the Illumina sequencing technology. A total of 62,348,602 clean reads were obtained. The assembly of the clean reads resulted in 146,943 transcripts, including 66,026 unigenes. In the assembled sequences, 1534 transcription factors were identified and classified into 23 different common families, and 9040 SSR loci, from di- to hexa-nucleotides, whose repeat number is greater than five, were presented. In addition, we performed a gene expression profiling analysis upon dehydration treatment. The results indicated significant differences in the gene expression profiles among the control, mild stress and severe stress. In total, 4687, 5648 and 5735 genes were identified from the comparison of mild versus control, severe versus control and severe versus mild stress, respectively. Based on the differentially expressed genes, a Gene Ontology annotation analysis indicated many dehydration-relevant categories, including 'response to water 'stimulus' and 'response to water deprivation'. Meanwhile, the Kyoto Encyclopedia of Genes and Genomes pathway analysis uncovered some important pathways, such as 'metabolic pathways' and 'plant hormone signal transduction'. In addition, the expression patterns of 25 putative genes that are involved in drought tolerance resulting from quantitative real-time PCR were consistent with their transcript abundance changes as identified by RNA-seq. The globally sequenced genes covered a considerable proportion of the S. moorcroftiana transcriptome, and the expression results may be useful to further extend the knowledge on the drought tolerance of this plant species that survives under Plateau conditions.