The Roles of GRETCHEN HAGEN3 (GH3)-Dependent Auxin Conjugation in the Regulation of Plant Development and Stress Adaptation.

The precise control of free auxin (indole-3-acetic acid, IAA) gradient, which is orchestrated by biosynthesis, conjugation, degradation, hydrolyzation, and transport, is critical for all aspects of plant growth and development. Of these, the GRETCHEN HAGEN 3 (GH3) acyl acid amido synthetase family, pivotal in conjugating IAA with amino acids, has garnered significant interest. Recent advances in understanding GH3-dependent IAA conjugation have positioned GH3 functional elucidation as a hot topic of research. This review aims to consolidate and discuss recent findings on (i) the enzymatic mechanisms driving GH3 activity, (ii) the influence of chemical inhibitor on GH3 function, and (iii) the transcriptional regulation of GH3 and its impact on plant development and stress response. Additionally, we explore the distinct biological functions attributed to IAA-amino acid conjugates.

Sitagliptin attenuates the progression of coronary atherosclerosis in patients with coronary disease and type 2 diabetes.

BACKGROUND AND AIMS: Type 2 diabetes mellitus (T2DM) is a well-recognized independent risk factor for ASCVD, the aim of this study was to investigate the effects of a dipeptidyl peptidase-4 inhibitor, sitagliptin, on prevention of progression of coronary atherosclerosis assessed by three-dimensional quantitative coronary angiography (3D-QCA) in T2DM patients with coronary artery disease (CAD). METHODS: This was a prospective, randomized, double-center, open-label, blinded end point, controlled 18-month study in patients with CAD and T2DM. A total of 149 patients, who had at least 1 atherosclerotic plaque with 20%-80% luminal narrowing in a coronary artery, and had not undergone intervention during a clinically indicated coronary angiography or percutaneous coronary intervention, were randomized to sitagliptin group (n = 74) or control group (n = 75). Atherosclerosis progression was measured by repeat 3D-QCA examination in 88 patients at study completion. The primary outcome was changes in percent atheroma volume (PAV) from baseline to study completion measured by 3D-QCA. Secondary outcomes included change in 3D-QCA-derived total atheroma volume (TAV) and late lumen loss (LLL). RESULTS: The primary outcome of PAV increased of 1.69% (95%CL, -0.8%-4.2%) with sitagliptin and 5.12% (95%CL, 3.49%-6.74%) with the conventional treatment (p = 0.023). The secondary outcome of change in TAV in patients treated with sitagliptin increased of 6.45 mm3 (95%CL,-2.46 to 6.36 mm3) and 9.45 mm3 (95%CL,-4.52 to 10.14 mm3) with conventional treatment (p = 0.023), however, no significant difference between groups was observed (p = 0.175). Patients treated with sitagliptin had similar LLL as compared with conventional antidiabetics (-0.06, 95%CL, -0.22 to 0.03 vs. -0.08, -0.23 to -0.03 mm, p = 0.689). CONCLUSIONS: In patients with type 2 diabetes and coronary artery disease, treatment with sitagliptin resulted in a significantly lower rate of progression of coronary atherosclerosis compared with conventional treatment.

Quantitatively ranking the influencing factors of ammonia volatilization from paddy soils by grey relational entropy.

Ammonia (NH3) volatilization from paddy soils is a main source of atmospheric NH3 and the magnitude is affected by many factors. Because of the complex field condition, it is difficult to identify the relative importance of individual factor on NH3 volatilization process in different locations and at different times. In this study, the grey relational entropy method was used to evaluate the relative impact of four main factors (i.e., nitrogen fertilizer application rate, NH4-N concentration, pH, and temperature of the floodwater) on NH3 volatilization loss from three different field experiments. The results demonstrated that floodwater NH4-N concentration was the most important factor governing NH3 volatilization process. Floodwater pH was the second most important factor, followed by temperature of the floodwater and nitrogen fertilizer application rate. We further validated the grey relational entropy method with NH3 volatilization loss data from other published study and confirmed the order of importance for the four factors. We hope the findings of this study will be helpful for guiding design to reduce paddy soil NH3 emission.

The Chloroplast Protease AMOS1/EGY1 Affects Phosphate Homeostasis under Phosphate Stress.

Plastid intramembrane proteases in Arabidopsis (Arabidopsis thaliana) are involved in jasmonic acid biosynthesis, chloroplast development, and flower morphology. Here, we show that Ammonium-Overly-Sensitive1 (AMOS1), a member of the family of plastid intramembrane proteases, plays an important role in the maintenance of phosphate (P) homeostasis under P stress. Loss of function of AMOS1 revealed a striking resistance to P starvation. amos1 plants displayed retarded root growth and reduced P accumulation in the root compared to wild type (Col-0) under P-replete control conditions, but remained largely unaffected by P starvation, displaying comparable P accumulation and root and shoot growth under P-deficient conditions. Further analysis revealed that, under P-deficient conditions, the cell wall, especially the pectin fraction of amos1, released more P than that of wild type, accompanied by a reduction of the abscisic acid (ABA) level and an increase in ethylene production. By using an ABA-insensitive mutant, abi4, and applying ABA and ACC exogenously, we found that ABA inhibits cell wall P remobilization while ethylene facilitates P remobilization from the cell wall by increasing the pectin concentration, suggesting ABA can counteract the effect of ethylene. Furthermore, the elevated ABA level and the lower ethylene production also correlated well with the mimicked P deficiency in amos1 Thus, our study uncovers the role of AMOS1 in the maintenance of P homeostasis through ABA-antagonized ethylene signaling.

Ecological surveys of the Cryptococcus species complex in China.

BACKGROUND: Despite recent reports on the molecular epidemiology of cryptococcal infections in China, clinical isolates have been mostly reported from human immunodeficiency virus (HIV)-negative patients, and environmental isolates from China have rarely been included. The aim of this study was to investigate the ecological profile of Cryptococcus (C.) neoformans and C. gattii in China. METHODS: A survey was performed in 10 cities from 20°N (North latitude) to 50°N and in a Eucalyptus (E.) camaldulensis forestry farm at the Guixi forestry center, China. RESULTS: Six hundred and twenty samples of pigeon droppings from 10 cities and 819 E. camaldulensis tree samples were collected and inoculated on caffeic acid cornmeal agar (CACA). The brown-colored colonies were recultured to observe their morphology, growth on canavanine-glycine-bromothymol-blue (CGB) medium, phenol oxidase and urease activities, serotype and mating type. There were obvious differences in the positive sample rates of C. neoformans in pigeon droppings collected from the different cities, ranging from 50% in the cities located at latitudes from 30°N - 40°N, 29% at 20°N - 30°N and 13% at 40°N - 50°N. CONCLUSIONS: There were no differences in positive bevy rates (approximately 80%) among the three grouped cities. Mycological tests of 101 isolates purified from pigeon droppings revealed that they were C. neoformans var. grubii. We also observed variable capsular size around the C. neoformans cells in colonies with variable melanin production and the bio-adhesion of the natural C. neoformans cells with other microorganisms. One urease-negative C. neoformans isolate was isolated from pigeon droppings in Jinan city. No C. gattii was isolated in this study.

Effects of nitrate supply site on selenite uptake by rice roots.

Selenite uptake by rice roots is regulated by many factors. The goal of this paper was to study the effects of the nitrate supply site on selenite uptake by rice roots. Using the excised-root experiment system, we found that, due to anion-anion interactions, nitrate can partly block the selenite uptake by rice roots by local action (a corporate supply of nitrate and selenite in the same portion). Using a split-root experiment system (whole-plant level), we found that (1) nitrate can also partly block selenite uptake by rice (roots and shoots) by local action; and that (2) under long-distance action (separate supply of nitrate and selenite in two different portions of the root), nitrate can partly facilitate selenite uptake by rice (roots and shoots), probably by regulating root glutathione content. Thus, our results suggest that nitrate can inhibit or facilitate selenite uptake by rice roots depending on the nitrate supply site.

Root growth inhibition by NH(4)(+) in Arabidopsis is mediated by the root tip and is linked to NH(4)(+) efflux and GMPase activity.

Root growth in higher plants is sensitive to excess ammonium (NH(4)(+)). Our study shows that contact of NH(4)(+) with the primary root tip is both necessary and sufficient to the development of arrested root growth under NH(4)(+) nutrition in Arabidopsis. We show that cell elongation and not cell division is the principal target in the NH(4)(+) inhibition of primary root growth. Mutant and expression analyses using DR5:GUS revealed that the growth inhibition is furthermore independent of auxin and ethylene signalling. NH(4)(+) fluxes along the primary root, measured using the Scanning Ion-selective Electrode Technique, revealed a significant stimulation of NH(4)(+) efflux at the elongation zone following treatment with elevated NH(4)(+), coincident with the inhibition of root elongation. Stimulation of NH(4)(+) efflux and inhibition of cell expansion were significantly more pronounced in the NH(4)(+)-hypersensitive mutant vtc1-1, deficient in the enzyme GDP-mannose pyrophosphorylase (GMPase). We conclude that both restricted transmembrane NH(4)(+) fluxes and proper functioning of GMPase in roots are critical to minimizing the severity of the NH(4)(+) toxicity response in Arabidopsis.

Expression profiling of the 14-3-3 gene family in response to salt stress and potassium and iron deficiencies in young tomato (Solanum lycopersicum) roots: analysis by real-time RT-PCR.

UNLABELLED: BACKGROUND AND AIMS Mineral nutrient deficiencies and salinity constitute major limitations for crop plant growth on agricultural soils. 14-3-3 proteins are phosphoserine-binding proteins that regulate the activities of a wide array of targets via direct protein-protein interactions and may play an important role in responses to mineral nutrients deficiencies and salt stress. In the present study, the expression profiling of the 14-3-3 gene family in response to salt stress and potassium and iron deficiencies in young tomato (Solanum lycopersicum) roots was investigated in order to analyse the 14-3-3 roles of the proteins in these abiotic stresses. METHODS: Sequence identities and phylogenetic tree creation were performed using DNAMAN version 4.0 (Lynnon Biosoft Company). Real-time RT-PCR was used to examine the expression of each 14-3-3 gene in response to salt stress and potassium and iron deficiencies in young tomato roots. KEY RESULTS: The phylogenetic tree shows that the 14-3-3 gene family falls into two major groups in tomato plants. By using real-time RT-PCR, it was found that (a) under normal growth conditions, there were significant differences in the mRNA levels of 14-3-3 gene family members in young tomato roots and (b) 14-3-3 proteins exhibited diverse patterns of gene expression in response to salt stress and potassium and iron deficiencies in tomato roots. CONCLUSIONS: The results suggest that (a) 14-3-3 proteins may be involved in the salt stress and potassium and iron deficiency signalling pathways in young tomato roots, (b) the expression pattern of 14-3-3 gene family members in tomato roots is not strictly related to the position of the corresponding proteins within a phylogenetic tree, (c) gene-specific expression patterns indicate that isoform-specificity may exist in the 14-3-3 gene family of tomato roots, and (d) 14-3-3 proteins (TFT7) might mediate cross-talk between the salt stress and potassium and iron-deficiency signalling pathways in tomato roots.