Yellow nutsedge WRI4-like gene improves drought tolerance in Arabidopsis thaliana by promoting cuticular wax biosynthesis.

BACKGROUND: Cuticular wax plays important role in protecting plants from drought stress. In Arabidopsis WRI4 improves drought tolerance by regulating the biosynthesis of fatty acids and cuticular wax. Cyperus esculentus (yellow nutsedge) is a tough weed found in tropical and temperate zones as well as in cooler regions. In the current study, we report the molecular cloning of a WRI4-like gene from Cyperus esculentus and its functional characterization in Arabidopsis. RESULTS: Using RACE PCR, full-length WRI-like gene was amplified from yellow nutsedge. Phylogenetic analyses and amino acid comparison suggested it to be a WRI4-like gene. According to the tissue-specific expression data, the highest expression of WRI4-like gene was found in leaves, followed by roots and tuber. Transgenic Arabidopsis plants expressing nutsedge WRI4-like gene manifested improved drought stress tolerance. Transgenic lines showed significantly reduced stomatal conductance, transpiration rate, chlorophyll leaching, water loss and improved water use efficiency (WUE). In the absence of drought stress, expression of key genes for fatty acid biosynthesis was not significantly different between transgenic lines and WT while that of cuticular wax biosynthesis genes was significantly higher in transgenic lines than WT. The PEG-simulated drought stress significantly increased expression of key genes for fatty acid as well as wax biosynthesis in transgenic Arabidopsis lines but not in WT plants. Consistent with the gene expression data, cuticular wax load and deposition was significantly higher in stem and leaves of transgenic lines compared with WT under control as well as drought stress conditions. CONCLUSIONS: WRI4-like gene from Cyperus esculentus improves drought tolerance in Arabidopsis probably by promoting cuticular wax biosynthesis and deposition. This in turn lowers chlorophyll leaching, stomatal conductance, transpiration rate, water loss and improves water use efficiency under drought stress conditions. Therefore, CeWRI4-like gene could be a good candidate for improving drought tolerance in crops.

Transcriptomic analysis of Eruca vesicaria subs. sativa lines with contrasting tolerance to polyethylene glycol-simulated drought stress.

BACKGROUND: Eruca vesicaria subsp. sativa is one of the Cruciferae species most tolerant to drought stress. In our previous study some extremely drought-tolerant/sensitive Eruca lines were obtained. However little is known about the mechanism for drought tolerance in Eruca. METHODS: In this study two E. vesicaria subs. sativa lines with contrasting drought tolerance were treated with liquid MS/PEG solution. Total RNA was isolated from 7-day old whole seedlings and then applied to Illumina sequencing platform for high-throughput transcriptional sequencing. RESULTS: KEGG pathway analysis indicated that differentially expressed genes (DEGs) involved in alpha-Linolenic acid metabolism, Tyrosine metabolism, Phenylalanine, Tyrosine and tryptophan biosynthesis, Galactose metabolism, Isoquinoline alkaloid biosynthesis, Tropane, Piperidine and pyridine alkaloid biosynthesis, Mineral absorption, were all up-regulated specifically in drought-tolerant (DT) Eruca line under drought stress, while DEGs involved in ribosome, ribosome biogenesis, Pyrimidine metabolism, RNA degradation, Glyoxylate and dicarboxylate metabolism, Aminoacyl-tRNA biosynthesis, Citrate cycle, Methane metabolism, Carbon fixation in photosynthetic organisms, were all down-regulated. 51 DEGs were found to be most significantly up-regulated (log2 ratio ≥ 8) specifically in the DT line under PEG treatment, including those for ethylene-responsive transcription factors, WRKY and bHLH transcription factors, calmodulin-binding transcription activator, cysteine-rich receptor-like protein kinase, mitogen-activated protein kinase kinase, WD repeat-containing protein, OPDA reductase, allene oxide cyclase, aquaporin, O-acyltransferase WSD1, C-5 sterol desaturase, sugar transporter ERD6-like 12, trehalose-phosphate phosphatase and galactinol synthase 4. Eight of these 51 DEGs wre enriched in 8 COG and 17 KEGG pathways. CONCLUSIONS: DEGs that were found to be most significantly up-regulated specifically in the DT line under PEG treatment, up-regulation of DEGs involved in Arginine and proline metabolism, alpha-linolenic acid metabolism and down-regulation of carbon fixation and protein synthesis might be critical for the drought tolerance in Eruca. These results will be valuable for revealing mechanism of drought tolerance in Eruca and also for genetic engineering to improve drought tolerance in crops.

Synthesis of pterodontic acid derivatives and the study of their anti-influenza A virus (H1N1) activity.

Laggera pterodonta (DC.) Benth, a folk herb widely distributes in southwest China, especially in Yunnan Province, demonstrates anti-pathogenic microorganisms, anti-inflammatory, inhibition of Helicobacter pylori activities in vitro et al. Interestingly, previous studies have shown that pterodontic acid (1), a eudesmane-type sesquiterpene isolated from L. pterodonta (DC.), displays excellent selective antiviral activity to H1N1 subtype of influenza A virus. At the same time, our group also discovered that the antiviral activity of 1 was relatively close to that activity of post-marketed ribavirin. Therefore, we consider that the synthesis of pterodontic acid (1) derivatives and evaluation of their anti-influenza A virus (H1N1) activities is of potential clinical significance. In this manuscript, a series of pterodontic acid derivatives were prepared and demonstrated significantly improved anti-influenza A virus (H1N1) activities, providing more opportunities for the treatment of respiratory viral diseases.