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PubMedDate not supplied

On the nature of rheumatoid rice bodies: an immunologic, histochemical, and electron microscope study.

The nature of rice bodies was studied, utilizing histochemistry, immunofluorescence, and scanning and transmission electron microscopy. Rice bodies were found to consist primarily of fibrous material, most of which was fibrin with small amounts of collagen. Channels containing a variety of viable cells permeated the rice bodies. Blood vessels occurred in a few rice bodies indicating a former connection with the synovial membrane. Nonvascularized rice bodies might represent a further degeneration of the vascular type. Rice bodies seem to be a nonspecific response to inflammation.

Arthritis, Rheumatoid↗

PubMed2026

Mapping the Molecular Evolution and Role of Wild Rice GLYIII Protein-Encoding Genes in Abiotic Stress Response.

To address the need for sustainable food production amid rapid global climate change, developing rice varieties that grow optimally even under harsh conditions is essential. An effective approach in this direction would be to harness the stress resilience traits of the crop wild relatives (CWRs) of rice. Among the various crucial stress-responsive genes, the Glyoxalase III (GLYIII) gene family is of utmost importance for its ability to detoxify the toxic glycolytic byproduct, methylglyoxal (MG), in a less energy-intensive, single-step process, as well as for its multifaceted cytoprotective role. In our study, a comprehensive genome-wide search across the Oryza genus revealed that GLYIII genes are conserved across wild rice genotypes. Their number has expanded during domestication, driven by gene duplications. Interestingly, only a few orthologous pairs showed positive selection, suggesting that the functions of most others need to be constrained and or conserved.We found that higher GLYIII activity, Total Antioxidant Capacity, endogenous glutathione (GSH) levels, and free radical scavenging activity contributes to the stress resilience of wild rices O. punctata, O. meridionalis, and O. nivara, in addition to other factors. , , . , . Our qRT-PCR analysis revealed differential expression of the OpGLYIII, OmGLYIII, and OnGLYIII genes across different developmental stages and in response to various abiotic stresses. Furthermore, we report that wild rice GLYIII proteins, specifically OpGLYIII-3, OmGLYIII-3, and OnGLYIII-5, exhibit high catalytic efficiency over a broad pH range and at higher temperatures under in vitro assay conditions. Overexpression of these proteins was found to impart substantial stress resilience to the transformed E. coli cells. These findings collectively suggest that GLYIII proteins constitute a key component of the abiotic stress response machinery in wild rice.

Oryza↗

PubMed2024

Transfer of antibiotic resistance genes from soil to rice in paddy field.

The global spread and distribution of antibiotic resistance genes (ARGs) has received much attention whereas knowledge about the transmission of ARGs from one matrix to another is still insufficient. In this study, the paddy fields fertilized with chemical fertilizer, swine compost, and no fertilizer were investigated to assess the transfer of ARGs from soil to rice. Soil and plant samples were collected at day 0, 7, 30 and 79 representing various stages of paddy growth. High throughput qPCR was applied to quantify ARGs using a set of 144 primers. Gene copy number of ARGs measured in soil initially decreased and then increased in soil with no fertilizer and chemical fertilizer, indicating that crop planting and flooding conditions did influence the ARGs profiles in soil. Application of swine compost significantly enhanced the relative abundance and gene copy number of ARGs in paddy soil. Rice seedlings contained substantial amount of ARGs and their relative abundance continually decreased after transplant. Compared with initial stage, detection frequencies of ARGs increased in soil without swine compost at harvest time (day 79), indicating the transmission of ARGs from irrigation water to soil. Detection frequencies of ARGs increased in soil and rice root with swine compost at harvest time, indicating the transfer of ARGs from swine compost to soil and rice root. There was no significant difference in abundance and diversity of ARGs in rice grains with these three different fertilizations. The source of the ARGs in rice grain still needs further exploration.

Oryza↗

PubMed2026

Alternatively spliced killer-protector system confers S19-mediated hybrid male sterility in rice.

Hybrid sterility limits the use of strong interspecific heterosis and S19 is a major locus that confers hybrid sterility between Oryza sativa (Asian cultivated rice) and Oryza glaberrima (African cultivated rice). However, the S19 is not yet cloned and its underlying mechanism remains elusive. In this study, we identify two closely linked genes (S19A1 and S19A7) specific to African rice allele that encode a killer-protector module at the S19 locus. Two alternatively spliced transcripts expressed from the killer gene S19A1 (S19A1.1 and S19A1.2) encode mitochondria-targeted cytotoxic proteins that cause toxicity diversity for somatic and/or gametic cell death, respectively. However, S19A7 interacts with S19A1.1 and S19A1.2, blocking their cytotoxic effect. Because the Asian rice S19 allele lacks S19A1 and S19A7, male gametes that carry this allele are selectively aborted in Asian-African F1 hybrids. Knockout of S19A1 can overcome S19-mediated hybrid sterility. Haplotype analysis reveals that the functional S19 allele is absent in non-AA-genome Oryza species and likely emerged in the O. barthii-O. glaberrima lineage through a multi-step evolutionary process. Our findings provide insight into the genetic mechanisms responsible for hybrid sterility between Asian and African rice and suggest genetic and biotechnological strategies for the use of interspecific heterosis in rice.

Oryza↗

PubMed1992

Molecular characterization of cDNA encoding for adenylate kinase of rice (Oryza sativa L.).

Two types of genes (Adk-a, and Adk-b) encoding for adenylate kinase (AK, EC 2.7.4.3.) were isolated from the cDNA library constructed from poly(A)+ RNA of rice (Oryza sativa L.). Two cDNAs were heterogeneous at 5' and 3' ends of non-coding sequences and had possible polyadenylation signals. One of the genes, Adk-a, had 1154 bp sequences encoding 241 amino acid residues, while the other type, Adk-b, contained 1085 bp sequences encoding for 243 amino acid residues. Homology between Adk-a and Adk-b was 73.7% in nucleotide sequences, and 90.8% in amino acid level. Two genes showed about 53% homology to bovine mitochondrial adenylate kinase (AK2) at nucleotide and amino acid levels. Concerning the codon usage of rice AK genes, T was abundant at the third position of a codon in the reading frames. In order to examine the enzyme activity of the protein encoded by the rice cDNA, Adk-a was cloned into an expression vector, pUC119, which was introduced into Escherichia coli strain CV2, a temperature-sensitive mutant of adenylate kinase. We found that the transformant carrying the rice Adk-a gene in the sense orientation recovered cell growth at non-permissive high temperature (42 degrees C) and expressed enzyme activities higher than the untransformed CV2 and the transformant possessing Adk-a cDNA in the antisense orientation. These observations suggest that rice Adk-a codes a biologically active enzyme. Furthermore, sucrose was found to regulate the transcription of AK genes in rice cell cultures. Organ related accumulation of mRNA in whole plants was also found.

Adenylate Kinase↗

PubMed1979

Protein quality of high-protein and low-protein milled rices in preschool children.

High-protein (11.0%, IR480-5-9) and low-protein (7.1%, IR32) milled rices were compared with casein as a control when fed as the main source of dietary N to eight apparently normal Filipino children, 1.5 to 2.0 years of age. Daily diets were formulated to contain 250 mg N and 100 kcal/kg body weight. Apparent digestibility of 60.0% for high-protein rice was lower than for low-protein rice (66.2%), and higher values of 76.8 and 80.8% were obtained for the two casein control diets. Corresponding apparent retentions were similar for the two rices, at 23.4 and 26.9%, respectively, as compared to 25.0 and 38.6% for the two casein control diets. These results support previous data on children fed non-isonitrogenous rice-based diets indicating that an increase in protein content of milled rice results in only a slight decrease in its protein quality. The results were similar to those obtained with Peruvian children on a similar protocol.

Amino Acids↗

PubMed2026

OsMYB8-OsARF12/25 module fine-tunes tiller angle via auxin signaling pathway in rice.

Tiller angle is a critical determinant of rice plant architecture and significantly impacts grain yield by influencing planting density and photosynthetic efficiency. Although auxin signaling is known to affect tiller angle in rice, the detailed regulatory networks remain largely unknown. In this study, we identify OsMYB8, an R2R3-MYB transcription factor, as a positive regulator of rice tiller angle. Functional analyses revealed that loss-of-function mutants of OsMYB8 exhibited reduced tiller angles and a more compact architecture, while overexpression of OsMYB8 resulted in more expanded tiller angles. Further investigations found that OsMYB8 might negatively regulate the shoot gravitropic response by disrupting asymmetric auxin distribution. At the molecular level, OsMYB8 directly binds to the promoters of 2 auxin response factors, OsARF12 and OsARF25, and represses their transcription. Genetic analyses confirmed that OsMYB8 acts upstream of OsARF12 and OsARF25 in regulating rice tiller angle. Our finding elucidates a previously uncharacterized OsMYB8-OsARF12/25 transcriptional module that fine-tunes auxin signaling to regulate tiller angle in rice, and offers valuable genetic targets for the optimization of rice architecture and yield potential.

Oryza↗

PubMed1977

Nutritional quality of rice protein compared with whole egg protein.

The nutritional quality of rice protein was compared with that of whole egg protein by slope ratio assay. Diets for each food at four levels of protein, 4, 6, 10 and 15% and a protein-free diet were given to male weanling rats of the Sprague-Dawley strain for 21 days. The slopes of the regression lines of the whole egg and rice groups calculated from the changes of body weight (Y in g/21 days) with nitrogen intake (X in g/21 days), including and (excluding) zero protein group were, respectively, Y=27.39 X-12.26 (Y=24.41 X-1.86) and Y = 13.86 X-8.06 (Y = 12.54 X +0.50). Assuming a potency of 100 for the egg protein, the relative potency of rice estimated from body weight gain with nitrogen intake was 51 (51). The values for rice calculated from body water gain and nitrogen retention with nitrogen intake were, respectively, 51 (47) and 46 (44). These values were compared with RNV of several varieties of conventional rice and high-protein rice.

Animals↗

PubMedDate not supplied

[Amino acid composition and biological value of rice proteins].

The nitrous substances of the home-grown rice variety-Dubovsky 129 were fractionated according to their solubility. The following fractions were separated: non-proteinic nitrogen, proteins dissoluble in saline, in alcohol and in alkaline solutions. The latter protein is the basic fraction, as concerns its amount. Further on subject to analysis was the amino acid composition of the total rice proteins and of all its fractions. The composition of the summary rice protein and its fractions includes all the essential amino acids, the first limiting amino acid of the rice proteins being lysine. The determination of the biological value of the rice proteins by the method of the amino acid score allows it to array the rice proteins as follows: dissoluble in saline greater than in alkaline greater than summary greater than in alcohol.

Amino Acids↗

PubMed2026

Molecular mechanisms underlying low glycemic index in rice: Insights from Indian landrace diversity.

The rising prevalence of diabetes mellitus, especially among populations with high rice consumption, underscores the need for functional staple crops with a low glycemic index (GI). This review examines the molecular and genetic factors influencing low-GI traits in rice, highlighting the importance of diversity within Indian landraces. Traditional cultivars like Mappillai Samba, Karuppu Kavuni and Kattuyanam contains high level of Resistant starch, dietary fiber and bioactive phytochemicals. The Waxy (Wx) gene, which codes for granule-bound starch synthase I (GBSSI), is very important for controlling the production of amylose. For example, functional alleles like Wxa and Wxlv are linked to higher amylose levels and lower starch digestibility. Moreover, secondary metabolites, such as anthocyanins and phytosterols like stigmasterol, play a role in regulating blood sugar levels by stopping the activities of α-amylase and α-glucosidase. Interactions within the starch-dietary matrix, including starch-protein, starch-lipid, and starch-polyphenol complexes, further influence enzymatic hydrolysis and glucose release kinetics. Recent advancements in genomics, encompassing QTL mapping and gene editing techniques, offer innovative prospects for the creation of biofortified, low-GI rice cultivars. The integration of these molecular insights into rice breeding programs can facilitate the development of low-glycemic, nutritionally enhanced rice cultivars that contribute to improved metabolic health and food security.

Oryza↗

PubMed2026

Mechanistic analysis of rice caryopsis morphogenesis regulated by exogenous hormones and related precursor substances under blue light conditions.

Rice caryopsis morphogenesis is regulated by light signals and hormonal networks. However, the mechanism by which exogenous hormones and related precursor substances modulate rice caryopsis morphogenesis under blue light remains elusive. In the present study, we aimed to elucidate the molecular mechanisms underlying the regulatory effects of exogenous phytohormones and related precursor substances on caryopsis development at 10 days after pollination (10 DAP) in the japonica rice cultivar 'Chujing 27' under blue light conditions. Results showed that tryptamine treatment increased caryopsis cell volume, thereby significantly driving caryopsis expansion; meanwhile, it markedly enhanced the activities of TDC and TAA, the key rate-limiting enzymes mediating the conversion of tryptophan to auxin, leading to a significant elevation in endogenous auxin content (P < 0.05). In comparison, exogenous auxin treatment significantly boosted carbohydrate accumulation and the activities of associated metabolic enzymes (P < 0.05). Integrated transcriptomic and metabolomic analyses revealed that tryptamine treatment led to significant enrichment of the starch and sucrose metabolic pathway, and drove the coordinated enhancement of carbon metabolic flux and auxin biosynthesis by upregulating key auxin biosynthetic genes (e.g., TAA1) and repressing auxin oxidative degradation. Genes Os04g0531100, Os03g0266100 and Os11g0221200 identified by weighted gene co-expression network analysis (WGCNA) may serve as important candidate targets regulating rice caryopsis morphology and physiological traits under blue light conditions. This study first uncovers the critical function of the "tryptamine-auxin axis" in regulating rice caryopsis development under blue light, laying a theoretical foundation for regulating caryopsis morphogenesis via exogenous hormones and their precursors.

Oryza↗

PubMed2025

A CRISPR/Cas9 mutant resource for OsSm RNA-binding genes in rice.

Pre-mRNA, produced by eukaryotic DNA transcription, undergoes splicing by the spliceosome, which removes introns and joins exons to form mRNA. The spliceosome is a large and highly dynamic molecular machine. Its core components include five small nuclear ribonucleoproteins (snRNPs) and the various spliceosome-related proteins. The conserved Smith (Sm) complex and the Sm-like proteins (LSm) serve as primary components of the snRNPs. Sm proteins are involved in processes such as pre-mRNA splicing and mRNA degradation, which can regulate gene expression, thereby influencing plant growth, development, and stress responses. While 25 Sm proteins have been identified in rice, their specific roles in regulating rice growth and development remain unclear. In this study, we employed the CRISPR/Cas9 system to edit 15 OsSm genes, and 13 mutants were obtained, with mutation rates ranging from 20.83 to 83.87%. In comparison to the wild type (WT), the mutants exhibited dwarfism, reduced tiller numbers, lower seed-setting rates or sterility, and increased susceptibility to diseases. One Sm mutant, ossmf-2, exhibited dwarfism, delayed flowering, and small grains. Through transcriptome analysis, three target genes, OsMRG702, OsRGG2, and OsLA1, were identified. Mutations of the OsSmF protein may lead to the abnormal splicing of these genes and finally lead to the inhibition of growth and development. Our study first edited the OsSm genes and generated a mutant library in rice. Most of the mutants exhibited abnormal growth and development, underscoring the essential roles of OsSm proteins in rice physiology. Furthermore, this work addresses a critical gap in the functional characterization of Sm proteins in rice. The resulting mutant collection offers valuable germplasm resources and lays a theoretical foundation for elucidating the molecular regulatory networks involving spliceosomal components and their target genes in the control of crop growth, development, and reproduction.

Oryza↗

PubMed2025

Functional genetics of rice PISTILLATA genes reveals new roles and target genes in flowering time, female fertility, and parthenocarpy.

Floral organ identity is controlled largely by the combinatorial action of MADS domain homeotic transcription factors. Lodicules are specialized plant organs in cereals and grasses that are involved in floret opening and facilitate pollination and fertility in rice (Oryza sativa L.). To understand the mechanisms underlying the specification of the rice lodicule, we investigated the developmental functions of the rice PISTILLATA (PI) paralogs, OsMADS2, and OsMADS4. Null osmads2 mutants reiterated OsMADS2 nonredundant lodicule specification roles and revealed new roles in flowering time and floral organ number and fate. Doubly perturbed osmads2 osmads4kd florets had severe abnormalities, were female infertile, yet could initiate parthenocarpy. Ubiquitous OsMADS4 overexpression rescued osmads2 abnormalities. We also utilized genome-wide binding analyses and transcriptome profiling to identify putative target genes contributing to OsMADS2 functions. In osmads2d8/d8 null mutant, we observed deregulated genes in a plethora of processes including lodicule and stamen development, floral organ number, and cell wall development. Some examples are cell division regulators (Cyclin D6, Cyclin-P4-1-like), an aquaporin (PIP1A), a peptide transporter, a vascular developmental regulator (HOX1), and a cell wall modulator (GH9B16). The deregulation of these genes may be associated with the disrupted cell division, tissue differentiation, and physiology of the malformed lodicules in osmads2 and osmads2 osmads4kd florets. Altogether, we reveal novel roles for the rice PI paralogs in flowering time, panicle exsertion, and embryo sac differentiation, identify gene targets for lodicule development, and provide mechanistic insights on the functional diversification of rice PI paralogs.

Oryza↗

PubMed2026

Multi-locus allelic architecture underlying natural variation in leaf rolling in japonica rice.

Leaf rolling is a key component of rice canopy architecture that affects light interception, microclimate formation, and planting density. The contribution of naturally occurring allelic variation to quantitative variation in leaf rolling within cultivated rice remains poorly understood, while extreme leaf rolling caused by loss-of-function mutations often results in detrimental pleiotropic effects. Herein, we examined how multi-locus allelic variation contributes to natural variation in leaf rolling within japonica rice. Leaf rolling was quantified based on the leaf rolling index (LRI) using a panel of 201 japonica accessions. The phenotype was transformed using the Yeo-Johnson method to reduce strong right skewness and improve the distributional properties of the data, thereby facilitating subsequent regression modeling. Haplotype analyses were performed for previously reported leaf rolling-associated genes and genome-wide association study (GWAS) lead loci, leading to the identification of five loci exhibiting substantial haplotype-dependent phenotypic variation. Phenotypically defined allelic groups represented these loci were subsequently evaluated using multiple linear regression (MLR), with the first two principal components derived from genome-wide SNP data included as covariates to account for population structure. The final MLR model identified four loci (qALR1, OsYABBY1, OsSLL2, and OsSRL10) as the independent contributors to leaf rolling variation, collectively explaining 21% of the variance in the transformed phenotype after accounting for population structure. Model diagnostics and ten-fold cross-validation supported the statistical validity of the framework and indicated stable model performance across validation folds. Analysis of multi-locus allelic combinations showed 13 distinct configurations that clustered into three phenotypically differentiated groups. This reflected the cumulative dosage of high-leaf rolling alleles. Thus, the natural variation in leaf rolling in japonica rice is governed by the additive effects of multiple moderate-impact loci. The multi-locus allelic framework established here provides a statistically sound and biologically interpretable basis for dissecting polygenic canopy traits and practical guidance for developing genetic materials aimed at optimizing rice plant architecture.

cross-validation↗

PubMed2026

OsDUF3615 regulates grain size and quality traits by modulating cell proliferation and starch metabolism in rice.

Domains of Unknown Function (DUFs) are widely distributed across diverse genomes and are increasingly recognized as important regulators of plant growth, development, and stress responses. DUF3615 is a highly conserved plant-specific protein motif; however, its biological function remains largely unknown. Previously, the gene OsGAPC3, a key regulator of grain quality, was isolated and functionally characterized in rice. Transcriptome analysis during the dissection of the OsGAPC3-mediated regulatory pathway revealed that OsDUF3615 is significantly upregulated in Osgapc3 mutants, suggesting its potential involvement in rice development and grain traits. In this study, we show that OsDUF3615 is constitutively expressed in rice and encodes a nucleus-localized protein. Functional analysis demonstrated that overexpression of OsDUF3615 significantly promotes cell proliferation and expansion in the lemma along the grain width axis, leading to increased grain width and thousand-grain weight. Moreover, OsDUF3615 modulates grain filling dynamics and alters the accumulation of major storage compounds, including starch and free fatty acids, thereby affecting both nutritional composition and eating quality traits, such as taste value. Collectively, our findings identify OsDUF3615 as a key regulator of rice grain development and quality formation, providing valuable genetic resources for the molecular breeding of high-quality rice varieties.

OsDUF3615↗

PubMedDate not supplied

An optimal rice-based oral rehydration solution: the effect of different concentrations of amylase on production of short chain polymers of glucose.

As part of a plan to develop a rice-based oral rehydration solution containing short polymers of glucose instead of glucose, we determined the concentration of amylase that would yield the largest amount of short chain polymers. Thai rice (25 g) was boiled with 500 ml of distilled water for 30 min. Of 200 ml supernatant rice water obtained, 100 ml were digested with different amounts of amylase after cooling to 50 degrees C for 60 min, boiled for 5 min, and centrifuged (10,000 g, 25 degrees C) for 60 min. The resulting supernatant (80 ml) was freeze-dried; 1.75 g of the powder obtained were dissolved in 3.5 ml of water, passed through a Bio-Gel P2 column to separate short chain polymers (2-9 molecules of glucose) and long chain polymers (> 9 molecules of glucose), which were identified by spectrophotometry (lambda = 190 nm) or by high performance liquid chromatography. Ten mg of amylase (equivalent to 12,000 modified Wohlgemath units) per 100 ml of rice water was optimal for the production of short polymers of glucose from rice.

Amylases↗

PubMed1977

Zinc, copper, cadmium and chromium in polished and unpolished rice.

One hundred samples of polished and 27 of unpolished rice were collected from 22 countries and areas and analyzed for Zn and Cu by flame atomic absorption, for Cd by carbon furnace atomic absorption, and for Cr by neutron activation. Unpolished rice contains on average 16.4 mug/g Zn, 4 mug/g Cu, 0.029 mug/g Cd and 0.011 mug/g Cr. Polished rice contains 13.7 mug/g Zn, 3 mug/g Cu, 0.029 mu/g Cd and 0.012 mug/g Cr. Thus, polishing brings about a loss of the essential elements Zn and Cu, but not of Cd, a toxic pollutant. Japanese rece has high Cd content. In countries where rice is a major staple food, high Cd content in rice may cause excessive absorption of this toxic metal.

Cadmium↗

PubMed2026

Natural variation in BRN1 enhances nitrogen sensitivity to improve rice nitrogen use efficiency.

Green Revolution rice varieties deliver high yields but require excessive nitrogen (N) fertilizer and show diminished N responsiveness, severely reducing nitrogen-use efficiency (NUE). To dissect the molecular basis of low N sensitivity in modern cultivars, we conducted a genome-wide association study (GWAS) for biomass response to N (BRN), a trait tightly linked to N sensitivity, using a diverse rice germplasm panel. We identified BRN1 as a key regulator of N-dependent biomass accumulation that regulates NLP3, a master transcription factor governing nitrate signaling. Under elevated N supply, the strigolactone signaling repressor D53 accumulates substantially and interacts with BRN1 to repress NLP3 transcription, thereby reducing rice N response. Notably, the high-response BRN1H allele encodes a more stable protein that alleviates D53-mediated suppression. Introgression of this allele into modern cultivars significantly enhanced N sensitivity and grain yield under both low and high N conditions. Our findings establish a D53-BRN1-NLP3 regulatory module controlling rice NUE, providing a target for rice breeding to sustain high productivity with improved resource sustainability.

Oryza↗