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Prolonged drought presents a serious challenge to the agricultural sector. The main concern of this work was to assess the phenotypical, physiological, and molecular responses of five teosinte (Zea mexicana Schrad L.) genotypes (Ba, Gm1, Gm2, Gm3 and Gm4). In a two-season (2020 and 2021) field experiment, fifteen-day-old teosinte plants were subjected to well-watered (15-day watering frequency) as a control, moderate drought (25-day watering frequency), and extreme drought (35-day watering frequency) treatments. Drought negatively affected growth, yield, chlorophyll, and POD activity of all genotypes, but promoted soluble sugars and proteins, osmoregulatory molecules (glycinebetaine, amino acids, and proline), non-enzymatic antioxidants (phenols, flavonoids, and alkaloids), and SOD activity. Furthermore, long-term water stress upregulated MOCOS, Rad17, NCED1, CAT1, and P5CS genes expression, with Gm3 and Gm4 being the most drought-tolerant genotypes. These findings could be employed in breeding programs to develop tolerant genotypes to address the challenges posed by climate changes like drought.

Prolonged drought presents a serious challenge to the agricultural sector. The main concern of this work was to assess the phenotypical, physiological, and molecular responses of five teosinte (Zea mexicana Schrad L.) genotypes (Ba, Gm1, Gm2, Gm3 and Gm4). In a two-season (2020 and 2021) field experiment, fifteen-day-old teosinte plants were subjected to well-watered (15-day watering frequency) as a control, moderate drought (25-day watering frequency), and extreme drought (35-day watering frequency) treatments. Drought negatively affected growth, yield, chlorophyll, and POD activity of all genotypes, but promoted soluble sugars and proteins, osmoregulatory molecules (glycinebetaine, amino acids, and proline), non-enzymatic antioxidants (phenols, flavonoids, and alkaloids), and SOD activity. Furthermore, long-term water stress upregulated MOCOS, Rad17, NCED1, CAT1, and P5CS genes expression, with Gm3 and Gm4 being the most drought-tolerant genotypes. These findings could be employed in breeding programs to develop tolerant genotypes to address the challenges posed by climate changes like drought. [ABSTRACT FROM AUTHOR]

Due to the importance of phosphorus (P) in agriculture, crop inoculation with phosphate-solubilizing bacteria is a relevant subject of study. Paenibacillus sonchi genomovar Riograndensis SBR5 is a promising candidate for crop inoculation, as it can fix nitrogen and excrete ammonium at a remarkably high rate. However, its trait of phosphate solubilization (PS) has not yet been studied in detail. Here, differential gene expression and functional analyses were performed to characterize PS in this bacterium. SBR5 was cultivated with two distinct P sources: NaH2PO4 as soluble phosphate source (SPi) and hydroxyapatite as insoluble phosphate source (IPi). Total RNA of SBR5 cultivated in those two conditions was isolated and sequenced, and bacterial growth and product formation were monitored. In the IPi medium, the expression of 68 genes was upregulated, whereas 100 genes were downregulated. Among those, genes involved in carbon metabolism, including those coding for subunits of 2-oxoglutarate dehydrogenase, were identified. Quantitation of organic acids showed that the production of tricarboxylic acid cycle-derived organic acids was reduced in IPi condition, whereas acetate and gluconate were overproduced. Increased concentrations of proline, trehalose, and glycine betaine revealed active osmoprotection during growth in IPi. The cultivation with hydroxyapatite also caused the reduction in the motility of SBR5 cells as a response to Pi depletion at the beginning of its growth. SBR5 was able to solubilize hydroxyapatite, which suggests that this organism is a promising phosphate-solubilizing bacterium. Our findings are the initial step in the elucidation of the PS process in P. sonchi SBR5 and will be a valuable groundwork for further studies of this organism as a plant growth-promoting rhizobacterium. [ABSTRACT FROM AUTHOR]

Hypertonicity in renal medulla is critical for the kidney to produce concentrated urine. Renal medullary cells have to survive high medullary osmolarity during antidiuresis. Previous study reported that farnesoid X receptor (FXR), a nuclear receptor transcription factor activated by endogenous bile acids, increases urine concentrating ability by up-regulating aquaporin 2 expression in medullary collecting duct cells (MCDs). However, whether FXR is also involved in the maintenance of cell survival of MCDs under dehydration condition and hypertonic stress remains largely unknown. In the present study, we demonstrate that 24-hours water restriction selectively up-regulated renal medullary expression of FXR with little MCD apoptosis in wild-type mice. In contrast, water deprivation caused a massive apoptosis of MCDs in both global FXR gene-deficient mice and collecting duct-specific FXR knockout mice. In vitro studies showed that hypertonicity significantly increased FXR and tonicity response enhancer binding protein (TonEBP) expression in mIMCD3 cell line and primary cultured MCDs. Activation and overexpression of FXR markedly increased cell viability and decreased cell apoptosis under hyperosmotic conditions. In addition, FXR can increase gene expression and nuclear translocation of TonEBP. We conclude that FXR protects MCDs from hypertonicity-induced cell injury very likely via increasing TonEBP expression and nuclear translocation. This study provides insights into the molecular mechanism by which FXR enhances urine concentration via maintaining cell viability of MCDs under hyperosmotic condition. [ABSTRACT FROM AUTHOR]

Pseudomonas sp. strain ATCC19151 is a natural isolate from sewage with the ability to degrade detergents. Genes encoding potential choline sulfatase ( betC), substrate-binding ABC transporter protein ( betD), sulfate transporter ( betE), and divergent putative transcriptional regulator ( betR) were cloned and characterized from strain ATCC19151. In silico analysis revealed that (1) the BetC protein belongs to alkPPc superfamily and shares CXPXR sequence with the cysteine sulfatases of group I, (2) BetR belongs to the LysR family of transcriptional regulators, (3) BetD is part of the PBPb superfamily of periplasmic and membrane-associated proteins, and (4) BetE is a permease and contains STAS domain. Insertional mutagenesis and genetic complementation show that betC gene encodes a functional choline sulfatase. Analysis of the betC (P) and betR (P) promoters revealed that they are inducible. BetR activates betC and betR transcription in the presence of choline sulfate, whilst in the absence of choline sulfate, BetR represses its own transcription. It was further established that BetR directly binds to betC- betR intergenic region in vitro, with higher affinity in the presence of choline sulfate as cofactor. Transcription of betC and betR was not induced in the presence of high concentration of NaCl. [ABSTRACT FROM AUTHOR]

Maize employs complex mechanisms of gene regulation in response to drought stress. Micro-RNAs (miRNAs) have emerged as a novel regulatory mechanism of gene expression. Drought induces upregulation and downregulation of numerous genes. However, little is known about the role of miRNAs in maize drought response. In this research, miRNA microarray hybridization showed that 34 miRNAs from 13 plant miRNA families had significantly altered expression after drought treatment. Most of the miRNA-mediated target genes contained a cis-acting element that responded to phytohormone (ABA) stimuli during drought stress. Drought stress-upregulated miR474 could downregulate target gene PDH, which is a negative regulator of proline accumulation, to improve osmoprotection responses to drought stress. On the other hand, drought-downregulated miRNAs (such as miR168, miR528, and miR167) might result in accumulation of their target mRNAs (MAPK, POD, and PLD) to initiate the regulation of ABA-induced stomatal movement and antioxidant defense. [ABSTRACT FROM AUTHOR]

Abstract: TonEBP/NFAT5 transcription factor is a master regulator of genes involved in osmoprotection. Cyclooxygenase 2 (COX2) has been reported to be a cytoprotective molecule in the inner renal medulla, where cells are physiologically exposed to the highest osmolality of the body. Our aim was to study whether COX2 expression requires TonEBP/NFAT5. Incubation of MDCK cells in hypertonic NaCl medium (500mOsm/kg H2O) caused fully translocation of TonEBP/NFAT5 from cytoplasm to nucleoplasm and significantly increased COX2 mRNA, protein and activity levels. TonEBP/NFAT5-siRNA prevented hypertonic induction of COX2 mRNA and protein, leading to a depressed-prostaglandin synthesis and to a decreased cell survival. By using COX2-siRNA and COX2 specific inhibitor NS398, we found that cell survival does not depend on endogenous COX2-induced prostaglandin synthesis, but that cytoprotection strongly correlates with COX2 protein levels. These results demonstrate a new function for TonEBP/NFAT5, i.e., to mediate hypertonic-induced COX2 expression, and suggest that osmoprotection strongly depends on COX2 protein levels. [Copyright &y& Elsevier]

In brain osmoprotective genes known to be involved in cellular osmoadaptation to hypertonicity, as well as the related transcription factor tonicity-responsive enhancer binding protein (TonEBP) are only expressed in some cell subsets. In the search for other genes possibly involved in osmoadaptation of brain cells we have analyzed, through microarray, the transcriptional profile of forebrain from rats subjected to 45 min, 90 min, and 6 h systemic hypertonicity. Microarray data were validated by quantitative real-time PCR. Around 23 000 genes gave a reliable hybridization signal. The number of genes showing a higher expression increased from around 15 (45 min) up to nearly 200 (6 h). Among about 30 immediate early genes (IEGs) encoding transcription factors, only Atf3, Verge, and Klf4 showed a rapid increased expression. TonEBP-mRNA tissue level and TonEBP-mRNA labeling in neurons remained unchanged whereas TonEBP labeling was rapidly increased in neurons. Sodium-dependent neutral amino acid transporter-2 (SNAT2) encoded by gene Slc38a2 showed a delayed increased expression. The rapid tonicity-induced activation of Atf3, Verge, and Klf4 may regulate genes involved in osmoadaptation. Nfat5 encoding TonEBP is not an IEG and the early tonicity-induced expression of TonEBP in neurons may result from translational activation. Increased expression of sodium-dependent neutral amino-acid transporter 2 may lead to the cellular accumulation of amino acids for adaptation to hypertonicity. [ABSTRACT FROM AUTHOR]