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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]

The homeodomain leucine zipper (HD-Zip) transcription factors are involved in plant responses to abiotic stresses. In this study, we have identified a total of 52 HD-Zip genes from the released genome of perennial ryegrass (Lolium perenne), a cool-season turfgrass and forage species, which is relatively sensitive to heat and drought stresses. These HD-Zip genes are classified into classes I-IV, of which, 49 are evenly distributed on all seven chromosomes of perennial ryegrass whereas other 3 are on scaffolds. Cis -elements analysis showed that phytohormone, light signaling, and stress responsive elements are abundant in the promoter region of the HD-Zip genes. Expression analysis indicated that LpHOX24 and its paralog LpHOX22 were significantly induced by heat stress treatment. Ectopic overexpressing (OE) of LpHOX22 and LpHOX24 in Arabidopsis compromised plant osmotic stress tolerance as evidenced by declined survival rate with elevated electrolyte leakage (EL) and malondialdehyde (MDA) accumulation. Expression levels of several osmotic responsive genes were downregulated in OE lines. Additionally, heat stress tolerance was impaired in LpHOX22 and LpHOX24 overexpression transformants, along with increased EL and MDA content. Further analysis revealed that overexpression of LpHOX22 and LpHOX24 repressed the expressions of AtHSFAs and AtDREB2A when compared to wild type after heat stress treatment. In summary, LpHOX22 and LpHOX24 potentially functioned as negative regulators in perennial ryegrass in response to osmotic and heat stresses. • Fifty-two HD-Zip genes were identified from the perennial ryegrass genome. • LpHOX22 and LpHOX24 were significantly induced by heat stress. • LpHOX22 and LpHOX24 transgenes impaired osmotic and heat stress tolerances. • LpHOX22 and LpHOX24 repressed expression of stress responsive genes. [ABSTRACT FROM AUTHOR]