Festuca arundinacea is one of the most drought-tolerant species within the Lolium-Festuca complex and was used as a model for research aimed at identifying the chloroplast components involved in the proteomic response for drought stress in forage grasses. Individual F. arundinacea genotypes with contrasting levels of drought tolerance, the high-drought-tolerant (HDT) and the low-drought-tolerant (LDT) genotypes, were selected for comparative physiological and proteomic work. Measurements of water uptake, chlorophyll fluorescence, relative water content, electrolyte leakage, and gas exchange during drought and rewatering periods were followed by investigations on accumulation levels of chloroplast proteins before drought conditions, on d 3 and 11 of drought treatment, and after 10 d of subsequent watering, using two-dimensional gel electrophoresis. The proteins that were accumulated differentially between the selected plants were then identified by mass spectrometry. The LDT genotype revealed lower levels of water uptake and relative water content as drought progressed, and this was accompanied by lower levels of transpiration and net photosynthesis, and a higher level of electrolyte leakage observed in this genotype. Eighty-two protein accumulation profiles were compared between the HDT and LDT genotypes and ten proteins were shown to be differentially accumulated between them. The functions of the selected proteins in plant cells and their probable influence on the process of recovery after drought treatment in F. arundinacea are discussed.

Festuca arundinacea is a drought tolerant species. Lolium multiflorum has better forage quality but lower tolerance to abiotic stresses. Their hybrids offer an opportunity to perform research on the molecular basis of tolerance to drought. The aim of this work was to recognise the mechanisms of response to short-term drought (11 days) in a glasshouse in two L. multiflorum/F. arundinacea introgression forms with distinct levels of tolerance to long-term drought (14 weeks) in the field. Measurements of physiological parameters, analyses of protein accumulation profiles using two-dimensional gel electrophoresis, and mass spectrometry identification of proteins, which were accumulated differentially between the selected genotypes during short-term drought, were performed. Genotype 7/6, with lower yield potential during 14 weeks of drought, and lower ability to re-grow after watering, had a higher capacity for photosynthesis during 11 days of drought. Genotype 4/10, more tolerant to long-term drought, was able to repair damaged cell membranes after watering and was also characterised by lower transpiration during short-term drought. A total of 455 proteins were analysed, and the 17 that were differentially accumulated between the two genotypes were identified. The results of physiological and proteomic research led to a hypothesis that the higher photosynthetic capacity of genotype 7/6 could be due to a more efficient Calvin cycle, supported by higher accumulation of crucial proteins involving chloroplast aldolase.

Impact of photosynthetic and antioxidant capacities on drought tolerance of two closely related forage grasses, Festuca arundinacea and Festuca glaucescens, was deciphered. Within each species, two genotypes distinct in drought tolerance were subjected to a short-term drought, followed by a subsequent re-watering. The studies were focused on: (i) analysis of plant physiological performance, including: water uptake, abscisic acid (ABA) content, membrane integrity, gas exchange, and relative water content in leaf tissue; (ii) analysis of plant photosynthetic capacity (chlorophyll fluorescence; gene expression, protein accumulation, and activity of selected enzymes of the Calvin cycle); and (iii) analysis of plant antioxidant capacity (reactive oxygen species (ROS) generation; gene expression, protein accumulation and activity of selected enzymes). Though, F. arundinacea and F. glaucescens revealed different strategies in water uptake, and partially also in ABA signaling, their physiological reactions to drought and further re-watering, were similar. On the other hand, performance of the Calvin cycle and antioxidant system differed between the analyzed species under drought and re-watering periods. A stable efficiency of the Calvin cycle in F. arundinacea was crucial to maintain a balanced network of ROS/redox signaling, and consequently drought tolerance. The antioxidant capacity influenced mostly tolerance to stress in F. glaucescens.