Gamma-aminobutyric acid (GABA) is a ubiquitous four-carbon, non-protein amino acid. GABA has been widely studied in animal central nervous systems, where it acts as an inhibitory neurotransmitter. In plants, it is metabolized through the GABA shunt pathway, a bypass of the tricarboxylic acid (TCA) cycle. Additionally, it can be synthesized through the polyamine metabolic pathway. GABA acts as a signal in Agrobacterium tumefaciens-mediated plant gene transformation and in plant development, especially in pollen tube elongation (to enter the ovule), root growth, fruit ripening, and seed germination. It is accumulated during plant responses to environmental stresses and pathogen and insect attacks. A high concentration of GABA elevates plant stress tolerance by improving photosynthesis, inhibiting reactive oxygen species (ROS) generation, activating antioxidant enzymes, and regulating stomatal opening in drought stress. The transporters of GABA in plants are reviewed in this work. We summarize the recent research on GABA function and transporters with the goal of providing a review of GABA in plants.

Objective—To assess the effects of various doses of lipopolysaccharide (LPS) administered IV on plasma microminerals, magnesium, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 concentrations and serum cortisol concentrations in lactating goats. Animals—6 lactating goats. Procedures—Goats were allotted to 3 LPS-treatment groups: control (0 μg/kg), low LPS (10 μg/kg), and high LPS (50 μg/kg). Rectal temperatures and behaviors of goats were recorded immediately before a 10-minute IV infusion of LPS and at 0.5, 1, 2, 4, 6, 8, and 24 hours after infusion. Blood samples were obtained before IV infusion and at 0.5, 1, 2, 4, 6, 8, and 24 hours after infusion. Plasma zinc, copper, iron, and magnesium concentrations were determined by atomic absorption spectrometry; plasma TNF-α and IL-6 concentrations were measured by use of an ELISA; and serum cortisol concentrations were determined by use of a radioimmunoassay. Results—A monophasic fever developed in low-LPS and high-LPS groups. In the low-LPS and high-LPS group, plasma zinc concentrations decreased at 6 hours after infusion; compared with control groups. Plasma iron concentrations were lower at 24 hours after infusion in low-LPS and high-LPS groups than in the control group. Plasma TNF-α and IL-6 concentrations were higher in low-LPS and high-LPS groups than in the control group at 1, 2, and 4 hours after infusion. In low-LPS and high-LPS groups, serum cortisol concentrations increased from 0.5 hours onward and peaked at 1 (high-LPS group) and 2 (low-LPS group) hours after infusion. Conclusions and Clinical Relevance—Following IV infusion of LPS, the immune system is activated, which might affect micromineral homeostatic regulation and, subsequently, the metabolic health of lactating goats.

Variation in atmospheric carbon dioxide (CO₂) concentration can dictate plant growth and development and shape plant evolution. For paired populations of 31 Arabidopsis accessions, respectively, grown under 100 or 380 ppm CO₂, we compared phenotypic traits related to vegetative growth and flowering time. Four accessions showed the least variation in measured growth traits between 100 ppm CO₂ and 380 ppm CO₂ conditions, though all accessions exhibited a dwarf stature with reduced biomass under low CO₂. Our comparison of accessions also incorporated the altitude (indicated in meters) above sea level at which they were originally collected. Notably, An-1 (50 m), Est (50 m), Ws-0 (150 m), and Ler-0 (600 m) showed the least differences (lower decrease or increase) between treatments in flowering time, rosette leaf number, specific leaf weight, stomatal density, and less negative δ¹³C values. When variations for all traits and seedset were considered together, Ws-0 exhibited the least change between treatments. Our results showed that physiological and phenotypic responses to low CO₂ varied among these accessions and did not correlate linearly with altitude, thus suggesting that slower growth or smaller stature under ambient CO₂ may potentially belie a fitness advantage for sustainable growth under low CO₂ availability.

Salt cress (Eutrema salsugineum, aka Thellungiella salsuginea) is an extremophile and a close relative of Arabidopsis thaliana. To understand the mechanism of selection of complex traits under natural variation, we analyzed the physiological and proteomic differences between Shandong (SD) and Xinjiang (XJ) ecotypes. The SD ecotype has dark green leaves, short and flat leaves, and more conspicuous taproots, and the XJ ecotype had greater biomass and showed clear signs of senescence or leaf shedding with age. After 2-DE separation and ESI-MS/MS identification, between 25 and 28 differentially expressed protein spots were identified in shoots and roots, respectively. The proteins identified in shoots are mainly involved in cellular metabolic processes, stress responses, responses to abiotic stimuli, and aging responses, while those identified in roots are mainly involved in small-molecule metabolic processes, oxidation-reduction processes, and responses to abiotic stimuli. Our data revealed the evolutionary differences at the protein level between these two ecotypes. Namely, in the evolution of salt tolerance, the SD ecotype highly expressed some stress-related proteins to structurally adapt to the high salt environment in the Yellow River Delta, whereas the XJ ecotype utilizes the specialized energy metabolism to support this evolution of the short-lived xerophytes in the Xinjiang region.