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Salinity and drought conditions commonly result in osmotic and oxidative stresses, while salinity additionally causes ionic stress. In this study, we identified specific genes regulated by osmotic and ionic stresses in five Arabidopsis ecotypes. Shahdara (SHA) and C24 ecotypes were more tolerant to salt and drought stresses at the seedling growth stage, as evidenced by lower water loss rate, lower electrolyte leakage, and higher survival rate when compared to the other three ecotypes under drought and salinity conditions. Transcriptomic analysis revealed that 3700 and 2242 genes were differentially regulated by salt and osmotic stresses, respectively. Totally 78.1% of upregulated and 62.0% of downregulated genes by osmotic stress were also commonly regulated by salt stress. Gene ontology term enrichment analysis showed that auxin indole‐3‐acetic acid (IAA), abscisic acid, cytokinin, and gibberellic acid pathways were regulated by the osmotic stress, while IAA, jasmonic acid, and ethylene pathways were changed by the ionic stress. The nutrient and water uptake pathways were regulated by both the osmotic and ionic stresses, whereas ion transportation and kinase pathways were modulated by the ionic stress. Additionally, we characterized bHLH61 as a negative regulator in response to salt and drought stresses. This study provided new clues of plant responses to salt and drought stresses. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is an outstanding turfgrass and forage cultivated in temperate regions worldwide. However, poor tolerance to extreme cold, heat, or drought limits wide extension and cultivation. DEHYDRATION‐RESPONSIVE ELEMENT BINDING FACTOR1s (DREB1s) play a vital role in enhancing plant tolerance to abiotic stress, specifically for low‐temperature stress. In this study, a total of 24 LpDREB1 family members were identified from the released genome of perennial ryegrass. Phylogenetic analysis showed that the LpDREB1 genes are divided into 7 groups that have close relationships with rice homologues. Conserved motif analysis revealed that members within the same group have similar conserved motif compositions. All LpDREB1s lack introns, and the promoter sequences of LpDREB1 genes contain multiple cis‐acting elements associated with stress response, phytohormone signal transduction and plant growth and development. The majority of LpDREB1 genes were upregulated by drought, submergence, heat and cold stress treatments, including LpDREB1H2. Further investigation showed that LpDREB1H2 is localized in the nucleus. Overexpression of LpDREB1H2 in Arabidopsis induced the expression of cold‐responsive (COR) genes, increased the levels of osmotic adjusting substances, and enhanced antioxidant enzyme activities, thus improving the cold tolerance of Arabidopsis. This study lays a foundation for further understanding the function of LpDREB1 genes in perennial ryegrass and provides insights for plant stress tolerance breeding. [ABSTRACT FROM AUTHOR]

Bermudagrass is a widely used warm-season turfgrass species with superior stress tolerance. Due to limited genome information, detailed stress response mechanisms of bermudagrass were not extensively characterized. In this study, we compared transcriptomic and proteomic level changes of bermudagrass after treatments with drought, salt and submergence. The results showed that 31.9–61.4% unigenes were commonly changed by drought, salt and submergence. GO terms including electron transport or energy pathways, response to abiotic or biotic stimulus and response to stress were enriched by stress treatments using both RNA seq and i-TRAQ. Pathways including photosynthesis, amino acid metabolism, redox, N-metabolism, and glycolysis were also overrepresented after drought, salt and submergence treatments using both strategies. A great portion of unigenes involved in ABA pathway were activated whereas those related to IAA pathway were repressed. ABA responsive bZIP type TF CdABF2 was induced by drought and salt. Ectopic overexpression of CdABF2 increased ABA sensitivity and improved tolerance to osmotic and salt stress at germination stage in Arabidopsis. These results provided evidence to understand abiotic stress regulatory mechanisms and stress crosstalk in bermudagrass. • About 32–62% unigenes were commonly changed by drought, salt and submergence. • RNA seq and i-TRAQ data were moderately or poorly correlated. • ABA pathway unigenes were activated whereas those in IAA pathway were repressed. • CdABF2 was induced by drought and salt and altered ABA sensitivity during germination. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne) is a cool‐season turf and forage grass. Heat shock transcription factors (HSFs) play an important role in regulating plant abiotic stress. However, HSFs in perennial ryegrass have rarely been characterized. Here, 25 LpHSFs were identified from the perennial ryegrass genome. Phylogenetic analysis showed that the LpHSFs could be classified into 12 subclasses. Gene structure analysis showed that 22 LpHSFs have only one intron. Cis‐acting elements analysis revealed that the promoter of 15 LpHSFs contained hormone‐responsive and abiotic stress‐responsive elements. Expression profile analysis indicated that 24 LpHSFs were differentially expressed under submerge, drought, heat, and cold stresses. In addition, a subclass C2 gene, LpHSFC2b, was significantly induced by abiotic stresses. The LpHSFC2b protein is localized to the nucleus, and heterologous expression of LpHSFC2b in Arabidopsis improves plant thermotolerance. This study provides insights useful for the breeding of stress tolerance in perennial ryegrass. [ABSTRACT FROM AUTHOR]