Transcriptional and physiological data reveal the dehydration memory behavior in switchgrass (Panicum virgatum L.)

Abstract Background Switchgrass (Panicum virgatum L.) is a model biofuel plant because of its high biomass, cellulose-richness, easy degradation to ethanol, and the availability of extensive genomic information. However, a little is currently known about the molecular responses of switchgrass plants to dehydration stress, especially multiple dehydration stresses. Results Studies on the transcriptional profiles of 35-day-old tissue culture plants revealed 741 dehydration memory genes. Gene Ontology and pathway analysis showed that these genes were enriched in phenylpropanoid biosynthesis, starch and sucrose metabolism, and plant hormone signal transduction. Further analysis of specific pathways combined with physiological data suggested that switchgrass improved its dehydration resistance by changing various aspects of its responses to secondary dehydration stress (D2), including the regulation of abscisic acid (ABA) and jasmonic acid (JA) biosynthesis and signal transduction, the biosynthesis of osmolytes (l-proline, stachyose and trehalose), energy metabolism (i.e., metabolic process relating to photosynthetic systems, glycolysis, and the TCA cycle), and lignin biosynthesis. The transcriptional data and chemical substance assays showed that ABA was significantly accumulated during both primary (D1) and secondary (D2) dehydration stresses, whereas JA accumulated during D1 but became significantly less abundant during D2. This suggests the existence of a complicated signaling network of plant hormones in response to repeated dehydration stresses. A homology analysis focusing on switchgrass, maize, and Arabidopsis revealed the conservation and species-specific distribution of dehydration memory genes. Conclusions The molecular responses of switchgrass plants to successive dehydration stresses have been systematically characterized, revealing a previously unknown transcriptional memory behavior. These results provide new insights into the mechanisms of dehydration stress responses in plants. The genes and pathways identified in this study will be useful for the genetic improvement of switchgrass and other crops

Bioassay-Guided Isolation of Broad-Spectrum Fungicidal Active Compound from Artemisia ordosica

To avoid the widespread resistance of commercial fungicides, new broad-spectrum botanical fungicides need to be developed. In previous bioactive screening assays, extracts of Artemisia ordosica Krasch. (A. ordosica) had highly antifungal activities, but the responsible phytochemicals were unidentified. In this study, active compounds of A. ordosica extracts were identified using a bioassay-guided method, and antifungal assays were performed in vitro and in vivo. The bioactive compounds were dissolved in petroleum ether, and the best antifungal fraction contained four compounds: trans-dehydromatricaria ester (TDDE), 7, 4-demetylnringenin, capillarin, and stearic acid. Among them, TDDE exhibited the highest antifungal activity against six pathogenic fungi and five bacteria. It exhibited significant fungicidal activity against Thanatephorus cucumeris and Botrytis cinerea with EC50 values of 0.464 μg/mL and 1.4 μg/mL, respectively. The living tissue bioassay results showed that the relative protection effects (RPE) of TDDE on tomato leaves, tomato fruit, and strawberry leaves infected with B. cinerea reached 76.78%, 86.2%, and 80.89%, respectively. In pot experiments, the RPE on tomato and strawberry plants infected with B. cinerea reached 84.11% and 96.37%, respectively. Morphological and physiological examination showed that TDDE had significant inhibitory effects on mycelial growth, including increased top offshoot, contorted hyphal tips, and extravasated cytochylema. Meanwhile, bactericidal activities of TDDE were significantly higher than kanamycin and streptomycin in five bacteria, and the plant tissue experiments further demonstrated that it had an 88.31% RPE on walnut leaves infected with Xanthomonas campestris pv. jugiandis, 72.18% RPE on potato infected with Erwinia carotovora subsp. carotovora, and 82.50% RPE on kiwifruit branches infected with Pseudomonas syringae pv. actinidiae. The active compounds isolated from A. ordosica in this study show great potential value for developing broad-spectrum fungicides, and also provide an important way to identify and isolate new bioactive products from medicinal plants

Additional file 2: of Long non-coding RNAs of switchgrass (Panicum virgatum L.) in multiple dehydration stresses

Table S1. List of memory lncRNAs. Table S2. Primers used in qRT-PCR. Table S3. Expression summary of different samples and treatments. Table S4. List of differentially expressed lncRNAs. Table S5. LncRNAs annotated by antisense and upstream or downstream. Table S6. Differentially expressed lncRNAs and the annotated genes. Table S7. Differentially expressed lncRNAs annotated with differentially expressed genes. Table S8. GO term _ response to stress. Table S9. Top 20 pathway enriched in annotation genes. Table S10. LncRNAs and genes involved in ABA biosynthesis and signal transduction. Table S11. LncRNAs and genes involved in ETH biosynthesis and signal transduction. Table S12. LncRNAs and genes involved in starch and sucrose metabolism. Table S13. Dehydration response and transcriptional memory genes or lncRNAs in switchgrass, maize and Arabidopsis. (ZIP 3778 kb

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Additional file 3: Table: S2. Primers used in qRT-PCR

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Additional file 1: Figure S1. Overview of the RNA-Seq results and repeatability of different biological replicates. The first eight figures show the proportion of clean reads in the sequenced samples; the next three figures show the repeated expression of genes in two biological replicates; the last four figures showed the correlations between differentially expressed genes in two biological replicates. C, control; D1-2, the first and second dehydration stresses; R1, the first recovery period

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Additional file 12: Table S11. Common DMGs in switchgrass and maize

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Additional file 8: Table S7. Differentially expressed genes involved in the biosynthesis of L-proline, stachyose and trehalose

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Additional file 10: Table S9. Differentially expressed genes involved in glycolysis and TCA cycle

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Additional file 9: Table S8. Differentially expressed genes involved in photosynthesis

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Additional file 6: Table S5. Differentially expressed genes involved in JA biosynthesis and signal transduction