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Quinoa (Chenopodium quinoaWilld.) with a history of 5000 years as food is extremely rich in nutrients and bioactive compounds, including γ-aminobutyric acid (GABA), a natural four-carbon non-protein amino acid with great benefits to human health. In quinoa, GABA generally increases with the germination time, but the underlying molecular mechanism is unclear. Here, we found that the GABA content in quinoa varied significantly among 25 varieties using an automatic amino acid analyzer. Next, six varieties (three low-GABA and three high-GABA varieties) were used for further analyses. The content of GABA in six varieties all showed an increasing trend after germination. In addition, Pearson’s correlation analysis showed that the changes in GABA content were closely related to the transcript level or enzyme activity of three key enzymes including glutamate decarboxylase (GAD), GABA transaminase (GABA-T), and succinate-semialdehyde dehydrogenase (SSADH) in the GABA shunt, especially GAD. Based on RNA-sequencing analysis, eight GADgenes, two GABA-Tgenes, one SSADHgene, nine polyamine oxidase (PAO) genes, five diamine oxidase (DAO) genes, four 4-aminobutyraldehyde dehydrogenase (BADH) genes, and three thermospermine synthase ACAULIS5 (ACL5) genes were identified. Among these, CqGAD8 and CqGABA-T2 may make a greater contribution to GABA accumulation during quinoa germination.

Aluminum (Al) toxicity poses a significant constraint on field crop yields in acid soils. Zinc finger protein 36 (ZFP36) is well-documented for its pivotal role in enhancing tolerance to both drought and oxidative stress in rice. This study unveils a novel function of ZFP36 modulated by abscisic acid (ABA)-dependent mechanisms, specifically aimed at alleviating Al toxicity in rice. Under Al stress, the expression of ZFP36significantly increased through an ABA-dependent pathway. Knocking down ZFP36heightened Al sensitivity, while overexpressing ZFP36conferred increased resistance to Al stress. Additionally, our investigations revealed a physical interaction between ZFP36 and pyruvate dehydrogenase kinase 1 in rice (OsPDK1). Biochemical assays further elucidated that OsPDK1 phosphorylates ZFP36 at the amino acid site 73–161. Subsequent experiments demonstrated that ZFP36 positively regulates the expression of ascorbate peroxidases (OsAPX1) and OsALS1 by binding to specific elements in their upstream segments in rice. Through genetic and phenotypic analyses, we unveiled that OsPDK1 influences ABA-triggered antioxidant defense to alleviate Al toxicity by interacting with ZFP36. In summary, our study underscores that pyruvate dehydrogenase kinase 1 (OsPDK1) phosphorylates ZFP36 to modulate the activities of antioxidant enzymes via an ABA-dependent pathway, influencing tolerance of rice to soil Al toxicity.

In this study, kiwifruit-bitter gourdjuice was added to reconstituted milk at 5%, 10% and 15% (v/v) to prepare fermented milk (KBFM5, KBFM10and KBFM15). Fermented milk without kiwifruit-bitter gourd juice was used as control fermented milk (CFM). Compared with CFM, the viable counts of Streptococcus thermophiles (St)in KBFM5, KBFM10and KBFM15were increased by 4.5%, 6.5% and 5.9%, Lactobacillus bulgaricus (Lb)were increased by 2.9%, 7.1% and 4.3%, and Bifidobacterium adolescentis (Ba)were increased by 9.0%, 11.5% and 10.7%, respectively. The value of initial titratable acidity (TA) of CFM was 82.4°T, the TA values of KBFM5, KBFM10and KBFM15were increased by 3.5%, 6.4% and 5.7%, respectively. Compared with CFM (water-holding capacity (WHC) was 79.69%; syneresis value was 324.3 g/kg), WHC of KBFM5, KBFM10and KBFM15were increased by 2.2%, 14.8% and 7.1%, and the syneresis values were reduced by 9.7%, 11.3% and 10.7%, respectively. The firmness value of CFM, KBFM5, KBFM10and KBFM15was 22.71, 26.84, 27.90, 23.56 g, the cohesiveness value was 126.92, 139.82, 153.56, 132.82 g/s, the consistency value was 13.38, 16.36, 18.38, 14.58 g, and the index of viscosity was 4.93, 7.56, 9.29, 6.16 g/s, respectively. KBFM10has highest sensory scores (37.96-maximum 40) which was selected for investigation of volatile compounds and hypoglycemia activity. Thirty-six kinds of volatile compounds were identified in KBFM10and thirty kinds in CFM, which were mainly aldehydes, alcohols, acids, ketones, and esters. During 28 day refrigerated storage, the values of α-glucosidase inhibition of CFM was 21.6%, 30.27%, 26.61%, 24.59%, 22.82%. The values α-glucosidase inhibition of KBFM10was respectively increased by 28.61%, 34.13%, 38.67%, 36.07%, 37.77%. This study demonstrated that kiwifruit-bitter gourd juice can be added as an active ingredient in milk preparations to provide novel functional dairy products.

Polysaccharides from Trichosanthespeel (TPP) were obtained by ultrasound-assisted extraction. TPP-1 was separated from the TPP by Sephadex G-100 column chromatography. Phosphorylation of TPP-1 was carried out and phosphorylated TPP-1 was named as PTTP-1. The results of infrared spectra, 13C nuclear magnetic resonance spectra and 31P nuclear magnetic resonance spectra showed that the main structure of PTPP-1 was similar to that of TPP-1 and -H2PO3groups which were conjugated to C-6 of →4)-α-D-Manp-(1→, C-4 of →6)-α-D-Galp-(1→, C-2 and C-3 of →1)-α-L-Araf, C-2 of →1)-α-L-Araf-(3→, and C-6 and C-3 of →1)-α-D-Glcp. In vivoantiaging activity results proved that TTP-1 and PTTP-1 could both significantly improve the body weight, spleen index, and thymus index of the D-galactose-induced aging mice, increase the levels of superoxide dismutase, catalase, glutathione peroxidase, and reduce malondialdehyde contents in the liver, brain, and serum of aging mice. These results indicated that both TPP-1 and PTTP-1 presented significant antiaging activity. Moreover, PTTP-1 showed stronger antiaging effects in aging mice, indicating that phosphorylation improved antiaging effect.

When plants are exposed to hypoxic conditions, the level of γ-aminobutyric acid (GABA) in plant tissues increases by several orders of magnitude. The physiological rationale behind this elevation remains largely unanswered. By combining genetic and electrophysiological approach, in this work we show that hypoxia-induced increase in GABA content is essential for restoration of membrane potential and preventing ROS-induced disturbance to cytosolic K+homeostasis and Ca2+signaling. We show that reduced O2availability affects H+-ATPase pumping activity, leading to membrane depolarization and K+loss via outward-rectifying GORK channels. Hypoxia stress also results in H2O2accumulation in the cell that activates ROS-inducible Ca2+uptake channels and triggers self-amplifying “ROS-Ca hub,” further exacerbating K+loss via non-selective cation channels that results in the loss of the cell's viability. Hypoxia-induced elevation in the GABA level may restore membrane potential by pH-dependent regulation of H+-ATPase and/or by generating more energy through the activation of the GABA shunt pathway and TCA cycle. Elevated GABA can also provide better control of the ROS-Ca2+hub by transcriptional control of RBOH genes thus preventing over-excessive H2O2accumulation. Finally, GABA can operate as a ligand directly controlling the open probability and conductance of K+efflux GORK channels, thus enabling plants adaptation to hypoxic conditions.