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Chilling stress is one of the main abiotic factors affecting rice growth and yield. In rice, chlorophyllide a oxygenase encoded by OsCAO1 is responsible for converting chlorophyllide a to chlorophyllide b, playing a crucial role in photosynthesis and thus rice growth. However, little is known about the function of OsCAO1 in chilling stress responses. The presence of the cis-acting element involved in low-temperature responsiveness (LTR) in the OsCAO1 promoter implied that OsCAO1 probably is a cold-responsive gene. The gene expression level of OsCAO1 was usually inhibited by low temperatures during the day and promoted by low temperatures at night. The OsCAO1 knockout mutants generated by the CRISPR-Cas9 technology in rice (Oryza sativa L.) exhibited significantly weakened chilling tolerance at the seedling stage. OsCAO1 dysfunction led to the accumulation of reactive oxygen species and malondialdehyde, an increase in relative electrolyte leakage, and a reduction in antioxidant gene expression under chilling stress. In addition, the functional deficiency of OsCAO1 resulted in more severe damage to chloroplast morphology, such as abnormal grana thylakoid stacking, caused by low temperatures. Moreover, the rice yield was reduced in OsCAO1 knockout mutants. Therefore, the elevated expression of OsCAO1 probably has the potential to increase both rice yield and chilling tolerance simultaneously, providing a strategy to cultivate chilling-tolerant rice varieties with high yields. [ABSTRACT FROM AUTHOR]

High temperature is a significant environmental stress that limits plant growth and agricultural productivity. GDSL lipase is a hydrolytic enzyme with a conserved GDSL sequence at the N-terminus, which has various biological functions, such as participating in plant growth, development, lipid metabolism, and stress resistance. However, little is known about the function of the GDSL lipase gene in the heat tolerance of rice. Here, we characterized a lipase family protein coding gene HTA1, which was significantly induced by high temperature in rice. Rice seedlings in which the mutant hta1 was knocked out showed enhanced heat tolerance, whereas the overexpressing HTA1 showed more sensitivity to heat stress. Under heat stress, hta1 could reduce plant membrane damage and reactive oxygen species (ROS) levels and elevate the activity of antioxidant enzymes. Moreover, real-time quantitative PCR (RT-qPCR) analysis showed that mutant hta1 significantly activated gene expression in antioxidant enzymes, heat response, and defense. In conclusion, our results suggest that HTA1 negatively regulates heat stress tolerance by modulating the ROS accumulation and the expression of heat-responsive and defense-related genes in rice seedlings. This research will provide a valuable resource for utilizing HTA1 to improve crop heat tolerance. [ABSTRACT FROM AUTHOR]

Seed storability has a significant impact on seed vitality and is a crucial genetic factor in maintaining seed value during storage. In this study, RNA sequencing was used to analyze the seed transcriptomes of two rice thermo-sensitive genic male sterile (TGMS) lines, S1146S (storage-tolerant) and SD26S (storage-susceptible), with 0 and 7 days of artificial accelerated aging treatment. In total, 2658 and 1523 differentially expressed genes (DEGs) were identified in S1146S and SD26S, respectively. Among these DEGs, 729 (G1) exhibited similar regulation patterns in both lines, while 1924 DEGs (G2) were specific to S1146S, 789 DEGs (G3) were specific to SD26S, and 5 DEGs (G4) were specific to contrary differential expression levels. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that "translation", "ribosome", "oxidative phosphorylation", "ATP-dependent activity", "intracellular protein transport", and "regulation of DNA-templated transcription" were significantly enriched during seed aging. Several genes, like Os01g0971400, Os01g0937200, Os03g0276500, Os05g0328632, and Os07g0214300, associated with seed storability were identified in G4. Core genes Os03g0100100 (OsPMEI12), Os03g0320900 (V2), Os02g0494000, Os02g0152800, and Os03g0710500 (OsBiP2) were identified in protein–protein interaction (PPI) networks. Seed vitality genes, MKKK62 (Os01g0699600), OsFbx352 (Os10g0127900), FSE6 (Os05g0540000), and RAmy3E (Os08g0473600), related to seed storability were identified. Overall, these results provide novel perspectives for studying the molecular response and related genes of different-storability rice TGMS lines under artificial aging conditions. They also provide new ideas for studying the storability of hybrid rice. [ABSTRACT FROM AUTHOR]

Type 2 diabetes (T2D) is a commonly diagnosed condition that has been extensively studied. The composition and activity of gut microbes, as well as the metabolites they produce (such as short-chain fatty acids, lipopolysaccharides, trimethylamine N-oxide, and bile acids) can significantly impact diabetes development. Treatment options, including medication, can enhance the gut microbiome and its metabolites, and even reverse intestinal epithelial dysfunction. Both animal and human studies have demonstrated the role of microbiota metabolites in influencing diabetes, as well as their complex chemical interactions with signaling molecules. This article focuses on the importance of microbiota metabolites in type 2 diabetes and provides an overview of various pharmacological and dietary components that can serve as therapeutic tools for reducing the risk of developing diabetes. A deeper understanding of the link between gut microbial metabolites and T2D will enhance our knowledge of the disease and may offer new treatment approaches. Although many animal studies have investigated the palliative and attenuating effects of gut microbial metabolites on T2D, few have established a complete cure. Therefore, conducting more systematic studies in the future is necessary. [ABSTRACT FROM AUTHOR]

Cold stress significantly constrains the growth, development, productivity, and distribution of rice, particularly the indica cultivar, known for its susceptibility to cold, limiting its cultivation to specific regions. This study investigated the genes associated with cold responsiveness in the roots of two indica cultivars, SQSL (cold-tolerant) and XZX45 (cold-susceptible), through transcriptome dynamics analysis during the seedling stage. The analysis identified 8144 and 6427 differentially expressed genes (DEGs) in XZX45 and SQSL, respectively. Among these DEGs, 4672 (G2) were shared by both cultivars, while 3472 DEGs (G1) were specific to XZX45, and 1755 DEGs (G3) were specific to SQSL. Additionally, 572 differentially expressed transcription factors (TFs) from 48 TF families, including WRKY, NAC, bHLH, ERF, bZIP, MYB, C2H2, and GRAS, were identified. Gene Ontology (GO) enrichment analysis revealed significant enrichment of DEGs in the G3 group, particularly in the "response to cold" category, highlighting the crucial role of these specific genes in response to cold stress in SQSL. Furthermore, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated pronounced enrichment of DEGs in the G3 group in metabolic pathways such as "Pyruvate metabolism", "Glycolysis/Gluconeogenesis", and "Starch and sucrose metabolism", contributing to cold tolerance mechanisms in SQSL. Overall, this study provides comprehensive insights into the molecular mechanisms underlying cold responses in the indica cultivar, informing future genetic improvement strategies to enhance cold tolerance in susceptible indica rice cultivars. [ABSTRACT FROM AUTHOR]

Heat stress (HS) has become one of the major abiotic stresses that severely constrain rice growth. Abscisic acid (ABA) plays an important role in plant development and stress response. However, the effect of different concentrations of exogenous ABA on HS tolerance in rice still needs to be further elucidated. Here, we found that high concentrations of exogenous ABA increased HS damage in seedlings, whereas 10−12 M ABA treatment increased fresh and dry weight under HS relative to mock seedlings. Our further data showed that, in response to HS, 10−5 M, ABA-treated seedlings exhibited a lower chlorophyll content, as well as transcript levels of chlorophyll biosynthesis and antioxidant genes, and increased the accumulation of reactive oxygen species (ROS). In addition, the transcript abundance of some heat-, defense-, and ABA-related genes was downregulated on 10−5 M ABA-treated seedlings under HS. In conclusion, high concentrations of exogenous ABA reduced the HS tolerance of rice seedlings, and this negative effect could be achieved by regulating the accumulation of ROS, chlorophyll biosynthesis, and the transcription levels of key genes in seedlings under HS. [ABSTRACT FROM AUTHOR]

Heat stress caused by rapidly changing climate warming has become a serious threat to crop growth worldwide. Exogenous cytokinin (CK) kinetin (KT) has been shown to have positive effects in improving salt and drought tolerance in plants. However, the mechanism of KT in heat tolerance in rice is poorly understood. Here, we found that exogenously adequate application of KT improved the heat stress tolerance of rice seedlings, with the best effect observed when the application concentration was 10−9 M. In addition, exogenous application of 10−9 M KT promoted the expression of CK-responsive OsRR genes, reduced membrane damage and reactive oxygen species (ROS) accumulation in rice, and increased the activity of antioxidant enzymes. Meanwhile, exogenous 10−9 M KT treatment significantly enhanced the expression of antioxidant enzymes, heat activation, and defense-related genes. In conclusion, exogenous KT treatment regulates heat tolerance in rice seedlings by modulating the dynamic balance of ROS in plants under heat stress. [ABSTRACT FROM AUTHOR]

In this study, cadmium (Cd)-contaminated soils were bioremediated using the mixotrophic acidophiles in different scale-up cultivation stages. The free and attached bacterial and fungal diversities and community structures, and their effects on soil Cd removal were investigated. Percentages of dominant bacteria (Acidithiobacillus, Sulfobacillus, and Pseudomonas) and fungi (Acidomyces and Coniochaeta) between the free and attached communities exhibited the pronounced differences. The α-diversity of attached bacteria was higher than the free bacteria, while the distinct variations in attached and free fungi were not observed. However, the β-diversity between the free and attached bacteria and fungi was significantly changed. Solution pH and reduced glucose level affected the abundance patterns of Acidithiobacillus in free bacteria and Acidomyces in attached fungi, which had great contributions to the soil Cd removal efficiency. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is a staple food that is consumed worldwide, and hybrid rice has been widely employed in many countries to greatly increase yield. However, the frequency of extreme temperature events is increasing, presenting a serious challenge to rice grain quality. Improving hybrid rice grain quality has become crucial for ensuring consumer acceptance. This study compared the differences in milling quality, appearance quality, and physical and chemical starch properties of rice grains of five restorer lines (the male parent of hybrid rice) when they encountered naturally unfavorable temperatures during the filling period under field conditions. High temperatures (HTs) and low temperatures (LTs) had opposite effects on grain quality, and the effect was correlated with rice variety. Notably, R751, R313, and Yuewangsimiao (YWSM) were shown to be superior restorer lines with good resistance to both HT and LT according to traits such as head rice rate, chalkiness degree, chalky rice rate, amylose content, alkali spreading value, and pasting properties. However, Huazhan and 8XR274 were susceptible to sub-optimal temperatures at the grain-filling stage. Breeding hybrid rice with adverse-temperature-tolerant restorer lines can not only ensure high yield via heterosis but also produce superior grain quality. This could ensure the quantity and taste of rice as a staple food in the future, when extreme temperatures will occur increasingly frequently. [ABSTRACT FROM AUTHOR]

Frequent high temperature weather affects the growth and development of rice, resulting in the decline of seed–setting rate, deterioration of rice quality and reduction of yield. Although some high temperature tolerance genes have been cloned, there is still little success in solving the effects of high temperature stress in rice (Oryza sativa L.). Based on the transcriptional data of seven time points, the weighted correlation network analysis (WGCNA) method was used to construct a co–expression network of differentially expressed genes (DEGs) between the rice genotypes IR64 (tolerant to heat stress) and Koshihikari (susceptible to heat stress). There were four modules in both genotypes that were highly correlated with the time points after heat stress in the seedling. We further identified candidate hub genes through clustering and analysis of protein interaction network with known–core genes. The results showed that the ribosome and protein processing in the endoplasmic reticulum were the common pathways in response to heat stress between the two genotypes. The changes of starch and sucrose metabolism and the biosynthesis of secondary metabolites pathways are possible reasons for the sensitivity to heat stress for Koshihikari. Our findings provide an important reference for the understanding of high temperature response mechanisms and the cultivation of high temperature resistant materials. [ABSTRACT FROM AUTHOR]

To elucidate the mechanism underlying the response of rice to heat stress (HS), the transcriptome profile of panicles was comparatively analyzed between the heat-tolerant line 252 (HTL252) and heat-susceptible line 082 (HSL082), two rice recombinant inbred lines (RILs). Our differentially expressed gene (DEG) analysis revealed that the DEGs are mainly associated with protein binding, catalysis, stress response, and cellular process. The MapMan analysis demonstrated that the heat-responsive (HR) genes for heat shock proteins, transcription factors, development, and phytohormones are specifically induced in HTL252 under HS. Based on the DEG analysis, the key gene OsNCED1 (Os02g0704000), which was induced under HS, was selected for further functional validation. Moreover, 9-cis-epoxycarotenoid dioxygenase (NCED) is a key rate-limiting enzyme in the ABA biosynthetic pathway. Overexpression of OsNCED1 improved the HS tolerance of rice at the heading and flowering stage. OsNCED1-overexpression plants exhibited significant increases in pollen viability, seed setting rate, superoxide dismutase (SOD) and peroxidase (POD) activities, while significantly lower electrolyte leakage and malondialdehyde (MDA) content relative to the wild type (WT). These results suggested that OsNCED1 overexpression can improve the heat tolerance of rice by enhancing the antioxidant capacity. Overall, this study lays a foundation for revealing the molecular regulatory mechanism underlying the response of rice to prolonged HS. [ABSTRACT FROM AUTHOR]

Oleaginous microalgae have been considered promising sources of biodiesel due to their high lipid content. Nitrogen limitation/starvation is one of the most prominent strategies to induce lipid accumulation in microalgae. Nonetheless, despite numerous studies, the mechanism underlying this approach is not well understood. The aim of this study was to investigate the effect of nitrogen limitation and starvation on biochemical and morphological changes in the microalga Chlorella vulgaris FACHB-1068, thereby obtaining the optimal nitrogen stress strategy for maximizing the lipid productivity of microalgal biomass. The results showed that nitrogen limitation (nitrate concentration < 21.66 mg/L) and starvation enhanced the lipid content but generally decreased the biomass productivity, pigment concentration, and protein content in algal cells. Comparatively, 3-day nitrogen starvation was found to be a more suitable strategy to produce lipid-rich biomass. It resulted in an increased biomass production and satisfactory lipid content of 266 mg/L and 31.33%, respectively. Besides, nitrogen starvation caused significant changes in cell morphology, with an increase in numbers and total size of lipid droplets and starch granules. Under nitrogen starvation, saturated fatty acids (C-16:0, C-20:0, and C-18:0) accounted for the majority of the total fatty acids (~80%), making C. vulgaris FACHB-1068 a potential feedstock for biodiesel production. Our work may contribute to a better understanding of the biochemical and morphological changes in microalgae under nitrogen stress. Besides, our work may provide valuable information on increasing the lipid productivity of oleaginous microalgae by regulating nitrogen supply. [ABSTRACT FROM AUTHOR]

Miscanthus spp. are energy plants and excellent candidates for phytoremediation approaches of metal(loid)s-contaminated soils, especially when combined with plant growth-promoting bacteria. Forty-one bacterial strains were isolated from the rhizosphere soils and roots tissue of five dominant plants (Artemisia argyi Levl., Gladiolus gandavensis Vaniot Houtt, Boehmeria nivea L., Veronica didyma Tenore, and Miscanthus floridulus Lab.) colonizing a cadmium (Cd)-contaminated mining area (Huayuan, Hunan, China). We subsequently tested their plant growth-promoting (PGP) traits (e.g., production of indole-3-acetic acid, siderophore, and 1-aminocyclopropane-1-carboxylate deaminase) and Cd tolerance. Among bacteria, two strains, Klebsiella michiganensis TS8 and Lelliottia jeotgali MR2, presented higher Cd tolerance and showed the best results regarding in vitro growth-promoting traits. In the subsequent pot experiments using soil spiked with 10 mg Cd·kg−1, we investigated the effects of TS8 and MR2 strains on soil Cd phytoremediation when combined with M. floridulus (Lab.). After sixty days of planting M. floridulus (Lab.), we found that TS8 increased plant height by 39.9%, dry weight of leaves by 99.1%, and the total Cd in the rhizosphere soil was reduced by 49.2%. Although MR2 had no significant effects on the efficiency of phytoremediation, it significantly enhanced the Cd translocation from the root to the aboveground tissues (translocation factor > 1). The combination of K. michiganensis TS8 and M. floridulus (Lab.) may be an effective method to remediate Cd-contaminated soils, while the inoculation of L. jeotgali MR2 may be used to enhance the phytoextraction potential of M. floridulus. [ABSTRACT FROM AUTHOR]

Acidithiobacillus thiooxidans A01 is widely used in bioleaching processes and commonly thrives in most metal-rich environments. However, interactions between different heavy metals remain obscure. In this study, we elaborated the effect of ferric iron on the growth and gene expression of At. thiooxidans A01 under the stress of nickel. The results showed that 600 mM Ni2+ completely inhibited the growth and sulfur metabolism of At. thiooxidans A01. However, trace amounts of Fe3+ (0.5 mM) facilitated the growth of At. thiooxidans A01 in the presence of 600 mM Ni2+. With the addition of 5 mM Fe3+, the maximum cell density reached 1.84 × 108 cell/mL, and pH value was 0.95. In addition, metal resistance-related and sulfur metabolism genes were significantly up regulated with extra ferric iron. Taking the whole process into account, the promoting effect of Fe3+ addition can be attributed to the following: (1) alleviation of the effects of Ni2+ toxicity and restoring the growth of At. thiooxidans A01, (2) a choice of multiple pathways to export nickel ion and producing precursor of chelators of heavy metals. This can suggest that microorganisms may widely exhibit metabolic activity in iron-rich environments with heavy metals. Our study will facilitate the technique development for the processing of ore bodies with highly challenging ore compositions. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests that the gut microbiota plays vital roles in metabolic diseases. Polygonatum odoratum extract alleviates hyperglycemia and hyperlipidemia, but the underlying mechanism remains unclear. This study investigated the effects of P. odoratum polysaccharides (POPs) on high-fat diet (HFD)-induced obesity in rats and whether these effects were related to modulation of gut microbiota. POP treatment attenuated weight gain, fat accumulation, epididymal adipocyte size, liver triglycerides, and total liver cholesterol content in HFD-fed rats. POP administration also increased short-chain fatty acids (SCFAs), including isobutyric acid, butyric acid, and valeric acid. POP upregulated the expression of genes involved in adipocyte differentiation (Pparg, Cebpa, Cebpb) and lipolysis (Ppara, Atgl), and downregulated those related to lipid synthesis (Srebpf1, Fabp4, Fas), with corresponding changes in PPARγ and FABP4 protein expression. Finally, POP enhanced species richness and improved the gut microbiota community structure, reducing the relative abundances of Clostridium, Enterococcus, Coprobacillus, Lactococcus, and Sutterella. Principal coordinates analysis (PCoA) revealed a clear separation between HFD-fed rats and all other treatment groups. Correlation analysis identified negative and positive associations between obesity phenotypes and 28 POP-influenced operational taxonomic units (OTUs), including putative SCFA-producing bacteria. Our data suggest that POP supplementation may attenuate features of obesity in HFD-fed rats in association with the modulation of gut microbiota. [ABSTRACT FROM AUTHOR]

Acidithiobacillus thiooxidans known for its ubiquity in diverse acidic and sulfur-bearing environments worldwide was used as the research subject in this study. To explore the genomic fluidity and intraspecific diversity of Acidithiobacillus thiooxidans (A. thiooxidans) species, comparative genomics based on nine draft genomes was performed. Phylogenomic scrutiny provided first insights into the multiple groupings of these strains, suggesting that genetic diversity might be potentially correlated with their geographic distribution as well as geochemical conditions. While these strains shared a large number of common genes, they displayed differences in gene content. Functional assignment indicated that the core genome was essential for microbial basic activities such as energy acquisition and uptake of nutrients, whereas the accessory genome was thought to be involved in niche adaptation. Comprehensive analysis of their predicted central metabolism revealed that few differences were observed among these strains. Further analyses showed evidences of relevance between environmental conditions and genomic diversification. Furthermore, a diverse pool of mobile genetic elements including insertion sequences and genomic islands in all A. thiooxidans strains probably demonstrated the frequent genetic flow (such as lateral gene transfer) in the extremely acidic environments. From another perspective, these elements might endow A. thiooxidans species with capacities to withstand the chemical constraints of their natural habitats. Taken together, our findings bring some valuable data to better understand the genomic diversity and econiche adaptation within A. thiooxidans strains.