N-treated control to drought-treated situations. These proteins are involved within the regulation of transcription and translation, cell division, cell wall modification, phyto-hormone metabolism and signaling transduction pathways, and metabolic pathways of carbohydrates, amino acids, and fatty acids. A scheme of abscisic acid (ABA)-biosynthesis and ABA responsive signal transduction pathway was reconstructed making use of these drought-induced significant proteins, displaying systemic regulation at protein level to deploy the respective mechanism. Benefits from this study, also to revealing molecular responses to drought tension, offer a big quantity of proteins (candidate genes) that may be employed to enhance switchgrass seedling growth and establishment under soil drought conditions (Data are out there by means of ProteomeXchange with identifier PXD004675). Keywords: physiological properties; isobaric tags for relative and absolute quantitation (iTRAQ); ProteoMiner; functional pathways; abscisic acid (ABA) signaling; “Sandwich” plant growth system1. Introduction Switchgrass (Panicum virgatum), has been selected as a model herbaceous bioenergy species in the USA because of its high biomass yield, robust tolerance to drought and flooding conditions, comparatively low herbicide and fertilizer input specifications, and widespread adaptability to temperate climate [1].Int. J. Mol. Sci. 2016, 17, 1251; doi:ten.Formula of 2-Methoxycyclopentan-1-one 3390/ijmswww.856562-91-9 Purity mdpi.PMID:24101108 com/journal/ijmsInt. J. Mol. Sci. 2016, 17,2 ofRecently, a shortage of fresh water and increasingly extreme drought have turn out to be a important challenge to crop production [4]. Based on information in the National Climate Service Centers for Environmental Prediction [5], soil moisture contents in the topsoil layer have declined over the previous decade (2005015) in many regions with the USA, specifically in central states. Drought tolerance is one of the most striking physiological properties of switchgrass. Mature plants have a quite deep root method and a extremely efficient C4 metabolic pathway [6]. On the other hand, switchgrass plants are slow to establish in the field, typically requiring two to 3 growing seasons to create deep root systems. During the early stages of development when seedlings possess a fairly shallow root distribution (05 cm) inside the best soil, these plants are extremely susceptible to both periodic and long-term drought conditions [7]. A field trial shows that drought considerably affected seedling growth of switchgrass within the first year. Furthermore, biomass yield declined considerably soon after 3 consecutive years of drought [8]. Therefore, developing switchgrass plants with robust drought tolerance throughout the early stages of development is definitely an productive approach to ensure high biomass yields for the duration of subsequent years inside the field. Plant growth is determined by cell division, cell enlargement, and differentiation [9]. Below drought situations, cell elongation and division are each suppressed by the lowered photosynthesis driven by diminished CO2 influx and limitation of carboxylation by abscisic acid (ABA)-dependent stomatal closure [92]. However, stomatal closing has been viewed as a drought tolerance mechanism to avoid excess water loss via transpiration. A set of physiological parameters related to drought tolerance has been identified which includes leaf relative water content material (RWC), electrolyte leakage (EL), photosynthetic price (Pn), stomatal conductance (gs ), transpiration price (Tr), intercellular CO2 concentration (Ci), and water use efficiency (WUE) [13]. Th.