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1.
Ecotoxicol Environ Saf ; 203: 111054, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888616

RESUMO

Quinclorac (3,7-dichloroquinoline-8-carboxylic acid, QNC) is a highly selective auxin herbicide that is typically applied to paddy rice fields. Its residue is a serious problem in crop rotations. In this study, Oryza sativa L. seedlings was used as a model plant to explore its biochemical response to abiotic stress caused by QNC and nZVI coexposure, as well as the interactions between QNC and nZVI treatments. Exposure to 5 and 10 mg/L QNC reduced the fresh biomass by 26.6% and 33.9%, respectively, compared to the control. The presence of 50 and 250 mg/L nZVI alleviated the QNC toxicity, but the nZVI toxicity was aggravated by the coexist of QNC. Root length was enhanced upon exposure to low or medium doses of both QNC and nZVI, whereas root length was inhibited under high-dose coexposure. Both nZVI and QNC, either alone or in combination, significantly inhibited the biosynthesis of chlorophyll, and the inhibition rate increased with elevated nZVI and QNC concentration. It was indicated that nZVI or QNC can affect the plant photosynthesis, and there was a significant interaction between the two treatments. Effects of QNC on the antioxidant response of Oryza sativa L. differed in the shoots and roots; generally, the introduction of 50 and 250 mg/L nZVI alleviated the oxidative stress (POD in shoots, SOD and MDA in roots) induced by QNC. However, 750 mg/kg nZVI seriously damaged Oryza sativa L. seedlings, which likely resulted from active iron deficiency. QNC could be removed from the culture solution by nZVI; as a result, nZVI suppressed QNC uptake by 20%-30%.


Assuntos
Antioxidantes/metabolismo , Ferro/toxicidade , Nanopartículas/toxicidade , Oryza/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Quinolinas/toxicidade , Poluentes do Solo/toxicidade , Transporte Biológico , Biomassa , Clorofila/metabolismo , Relação Dose-Resposta a Droga , Interações Medicamentosas , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/metabolismo
2.
Ecotoxicol Environ Saf ; 203: 110990, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888601

RESUMO

The presence of sulfamethoxazole (SMX) in croplands has become an international concern. The environmental behavior and fate of SMX in agricultural soils are not well understood, especially when the adsorption behavior is disturbed by the dissolved organic matter (DOM) released by crop straw. As canola straw is one of the biomasses widely returned to farmlands, we characterized DOM derived from pristine and decomposed canola straw, and explored the effects and mechanisms of the DOMs on regulating SMX adsorption to purple paddy soils. The spectral analysis showed that the molecular weight, aromaticity, and hydrophobicity of canola straw-derived DOM increased as decomposition proceeded. These physicochemical properties collectively determined the effects of the DOM on SMX adsorption. The DOM derived from pristine canola straw increased SMX maximum adsorption capacity of the soils by approximately 2.6 times, but this positive effect gradually decreased to a steady state by day 90 in the straw decomposition period. Nevertheless, the SMX adsorption behavior in the soils was invariably determined by the DOM extracts. These adsorption processes of SMX were well fitted by the double-chamber kinetics model and the Langmuir and Freundlich thermodynamic models. Thermodynamic parameters indicated that SMX adsorption onto the soils was spontaneous and endothermic, and this adsorption characteristics was not significantly (p > 0.05) changed by the DOM extracts. However, the adsorption kinetics were altered by those DOMs, i.e., the fast and slow adsorption processes were both diminished. Correspondingly, co-adsorption and cumulative adsorption were identified as the main mechanisms determining SMX adsorption to the purple paddy soils in the presence of the straw-derived DOMs. These results collectively indicated that the DOMs released by straw in croplands may decrease the ecological risks of organic pollutants by inhibiting their migration processes.


Assuntos
Brassica/química , Poluentes do Solo/química , Solo/química , Sulfametoxazol/química , Adsorção , Agricultura , Oryza/crescimento & desenvolvimento , Silagem
3.
Bull Environ Contam Toxicol ; 105(4): 572-581, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32960333

RESUMO

In order to assess the environmental impacts caused by flood to the paddy field, 940 semi-volatile organic compounds (SVOCs) were screened in paddy soil samples taken in central Vietnam before and after flooding. The concentration of 166 SVOCs in soil samples ranged from 0.031 to 2241 (mean 89.1) µg kg-1 dry wt. Chemicals originating from household sources showed the highest level, followed by chemicals originating from agriculture. Since untreated domestic wastewater used for agricultural irrigation, organic micro-pollutants in domestic wastewater is the main source of pollutants in paddy soil. However, contamination levels of pollutants in paddy soil after flooding were lower than those before flooding, possibly due to the removal of pollutants by floodwater. As a result, pollution characteristic of pollutants at sampling locations were different before flooding while they became similar after flooding due to the dispersion and elution of organic pollutants from soil into floodwaters.


Assuntos
Monitoramento Ambiental , Inundações , Compostos Orgânicos/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Oryza/crescimento & desenvolvimento , Solo/química , Vietnã
4.
Proc Natl Acad Sci U S A ; 117(33): 19816-19824, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32732432

RESUMO

Data recently published in PNAS mapped out regional differences in the tightness of social norms across China [R. Y. J. Chua, K. G. Huang, M. Jin, Proc. Natl. Acad. Sci. U.S.A. 116, 6720-6725 (2019)]. Norms were tighter in developed, urbanized areas and weaker in rural areas. We tested whether historical paddy rice farming has left a legacy on social norms in modern China. Premodern rice farming could plausibly create strong social norms because paddy rice relied on irrigation networks. Rice farmers coordinated their water use and kept track of each person's labor contributions. Rice villages also established strong norms of reciprocity to cope with labor demands that were twice as high as dryland crops like wheat. In line with this theory, China's historically rice-farming areas had tighter social norms than wheat-farming areas, even beyond differences in development and urbanization. Rice-wheat differences were just as large among people in 10 neighboring provinces (n = 3,835) along the rice-wheat border. These neighboring provinces differ sharply in rice and wheat, but little in latitude, temperature, and other potential confounding variables. Outside of China, rice farming predicted norm tightness in 32 countries around the world. Finally, people in rice-farming areas scored lower on innovative thinking, which tends to be lower in societies with tight norms. This natural test case within China might explain why East Asia-historically reliant on rice farming-has tighter social norms than the wheat-farming West.


Assuntos
Fazendeiros/psicologia , Oryza/crescimento & desenvolvimento , Normas Sociais , Adulto , Agricultura , China , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Triticum/crescimento & desenvolvimento , Urbanização , Adulto Jovem
5.
Ecotoxicol Environ Saf ; 204: 111104, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32791360

RESUMO

Since development of antioxidant defence system is high energy demanding event, innate defence system and stress tolerance of plant is strictly governed by plant age. This study is aimed towards evaluating variation of tolerance in germinating seeds and seedlings of Oryza sativa L. cv. Swarna against nano-scale zero valent iron (nZVI). A comparative study of several physiological and biochemical parameters have been carried out among 2 distinct plant groups, Group I treated with variable concentrations of nZVI (50, 100, 150 and 200 mg L-1) during germination and Group II treated with similar nZVI doses on 7th day after germination. Upon treatment with higher nZVI concentrations, Group I seedlings showed susceptibility towards oxidative stress while Group II seedlings showed tolerance against these higher doses of nZVI. Significant growth enhancement was observed upon treatment with 50-150 mg L-1 nZVI, since up-regulation of plant's endogenous antioxidant system protected relatively aged Group II seedlings from oxidative damages. Hierarchical clustering based on overall physiological, biochemical and stress parameters confirmed that in Group I seedlings 100-200 mg L-1 nZVI treatments were toxic where as in Group II seedlings 50-150 mg L-1 nZVI treatments showed growth promoting effects. This differential response is due to developmental stage related resistance in plants.


Assuntos
Germinação/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Oryza/crescimento & desenvolvimento , Antioxidantes/metabolismo , Ferro/metabolismo , Oryza/efeitos dos fármacos , Oxirredução , Estresse Oxidativo/efeitos dos fármacos , Plântula/efeitos dos fármacos , Sementes/metabolismo
6.
PLoS One ; 15(8): e0237844, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32834013

RESUMO

The feasibility of the production of germinated rice extracts using indigenous rice from Southern Thailand, including Khemtong (KHT) and Khai Mod Rin (KMR) from a single location at the Pak Phanang River Basin in Nakhon Si Thammarat, was investigated. The nutritional composition and bioactivity of the germinated rice extracts from both cultivars were evaluated. Optimum germination time for both rices was 96 h, leading to the highest GABA, thiamine, free amino acid, total sugar, and α-amylase activity (p<0.05). Germinated KHT had a higher α-amylase activity than germinated KMR at all germination times. Mashing at 60°C/pH 5.5 rendered the extract with the highest GABA content (p<0.05) and desirable contents of other nutrients. In comparison with germinated Sungyod (local colored rice) and Jasmine (commercial Thai rice) extracts, KHT and KMR showed a higher scavenging activity against DPPH•, OH•, and H2O2 (p<0.05) with a comparable ABTS•+ inhibition. For metal chelation, reducing power and ACE inhibitory activity, the germinated Sungyod extract was greater than KHT/KMR. The results demonstrated the potential use of germinated local Thai rice for the production of functional beverages.


Assuntos
Germinação , Fenômenos Fisiológicos da Nutrição , Oryza/química , Oryza/crescimento & desenvolvimento , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Aminoácidos/análise , Inibidores da Enzima Conversora de Angiotensina/farmacologia , Antioxidantes/farmacologia , Compostos de Bifenilo/química , Estudos de Viabilidade , Flavonoides/análise , Depuradores de Radicais Livres/química , Minerais/análise , Fenóis/análise , Ácido Fítico/análise , Picratos/química , Açúcares/análise , Tiamina/análise , Fatores de Tempo , alfa-Amilases/metabolismo , Ácido gama-Aminobutírico/análise
7.
Ecotoxicol Environ Saf ; 202: 110950, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800226

RESUMO

Human exposure to methylmercury (MeHg) through rice consumption is raising health concerns. It has long been recognized that MeHg found in rice grain predominately originated from paddy soil. Anaerobic conditions in paddy fields promote Hg methylation, potentially leading to high MeHg concentrations in rice grain. Understanding the transformation and migration of Hg in the rice paddy system, as well as the effects of farming activities, are keys to assessing risks and developing potential mitigation strategies. Therefore, this review examines the current state of knowledge on: 1) sources of Hg in paddy fields; 2) how MeHg and inorganic Hg (IHg) are transformed (including abiotic and biotic processes); 3) how IHg and MeHg enter and translocate in rice plants; and 4) how regular farming activities (including the application of fertilizer, cultivation methods, choice of cultivar), affect Hg cycling in the paddy field system. Current issues and controversies on Hg transformation and migration in the paddy field system are also discussed.


Assuntos
Produção Agrícola/métodos , Monitoramento Ambiental/métodos , Mercúrio/análise , Compostos de Metilmercúrio/análise , Oryza/efeitos dos fármacos , Poluentes do Solo/análise , Fertilizantes/análise , Humanos , Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Solo/química , Poluentes do Solo/metabolismo
8.
PLoS One ; 15(8): e0237774, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32797075

RESUMO

The source-sink relationship determines the ultimate grain yield of rice. In this study, we used a set of reciprocal introgression lines (ILs) derived from Xuishui09 × IR2061 to map quantitative trait loci (QTLs) that were associated with sink-, source-, and grain yield-related traits. A total of 95 QTLs influencing eight measured traits were identified using 6181 high-quality single nucleotide polymorphism markers. Nine background-independent QTLs were consistently detected in seven chromosomal regions in different genetic backgrounds. Seven QTLs clusters simultaneously affected sink-, source-, and grain yield-related traits, probably due to the genetic basis of significant correlations of grain yield with source and sink traits. We selected 15 candidate genes in the four QTLs consistently identified in the two populations by performing gene-based association and haplotype analyses using 2288 accessions from the 3K project. Among these, LOC_Os03g48970 for qTSN3b, LOC_Os06g04710 for qFLL6a, and LOC_Os07g32510 for qTGW7 were considered as the most likely candidate genes based on functional annotations. These results provide a basis for further study of candidate genes and for the development of high-yield rice varieties by balancing source-sink relationships using marker-assisted selection.


Assuntos
Grão Comestível/genética , Oryza/genética , Locos de Características Quantitativas , Cromossomos de Plantas/genética , Grão Comestível/crescimento & desenvolvimento , Genes de Plantas , Oryza/crescimento & desenvolvimento , Polimorfismo de Nucleotídeo Único
9.
Ecotoxicol Environ Saf ; 204: 111063, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32791358

RESUMO

The lipocalins genes have been assigned for involving in the responses of organisms to various stress factors. The function of lipocalins under PCB18 stress was addressed by pathway complementation in the Oryza sativa L. OsTIL-silenced mutant. The growth of wild type (WT) and OsTIL-silenced mutant (MT) callus were suppressed by PCB18, and MT varieties were inhibited more seriously than WT varieties. Meanwhile, only WT varieties showed "Hormesis" effect. Compared with WT (3 day > 90.0%, 6 day ≤45.5%), MT varieties kept high removing efficiency by HPLC analysis. Varied gene transcription after OsTIL silencing was demonstrated between two varieties, especially obvious under PCB stress. Silenced OsTIL induced more protective gene transcriptions by qPCR analysis, OsVDE at 3 day, OsCHL, OsZEP1, OsZEP2 and OsUN at 6 day and OsZEP2 at 9 day. PCB18 stress further irritated these genes transcription in MT varieties. The defense stagy in WT varieties was that the transcriptions of lipocalins were inhibited to reduce PCB18 accumulation and toxicity. OsTIL could effectively limit PCB18 accumulation and toxicity. After TIL lacking, OsCHL, OsZEP1, OsZEP2 and OsUN in mutant were strongly evoked to against PCB stress. Remarkably, OsUN and OsZEP2 gene expressions were responded to PCB18 stress in both two varieties.


Assuntos
Poluentes Ambientais/toxicidade , Lipocalinas/genética , Oryza/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Bifenilos Policlorados/toxicidade , Ativação Transcricional/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas , Inativação Gênica , Genes de Plantas , Oryza/genética , Oryza/crescimento & desenvolvimento , Estresse Oxidativo/genética
10.
Plant Mol Biol ; 104(1-2): 97-112, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32643113

RESUMO

KEY MESSAGE: By integrating genetics and genomics data, reproductive tissues-specific and heat stress responsive 35 meta-QTLs and 45 candidate genes were identified, which could be exploited through marker-assisted breeding for fast-track development of heat-tolerant rice cultivars. Rice holds the key to future food security. In rice-growing areas, temperature has already reached an optimum level for growth, hence, any further increase due to global climate change could significantly reduce rice yield. Several mapping studies have identified a plethora of reproductive tissue-specific and heat stress associated inconsistent quantitative trait loci (QTL), which could be exploited for improvement of heat tolerance. In this study, we performed a meta-analysis on previously reported QTLs and identified 35 most consistent meta-QTLs (MQTLs) across diverse genetic backgrounds and environments. Genetic and physical intervals of nearly 66% MQTLs were narrower than 5 cM and 2 Mb respectively, indicating hotspot genomic regions for heat tolerance. Comparative analyses of MQTLs underlying genes with microarray and RNA-seq based transcriptomic data sets revealed a core set of 45 heat-responsive genes, among which 24 were reproductive tissue-specific and have not been studied in detail before. Remarkably, all these genes corresponded to various stress associated functions, ranging from abiotic stress sensing to regulating plant stress responses, and included heat-shock genes (OsBiP2, OsMed37_1), transcription factors (OsNAS3, OsTEF1, OsWRKY10, OsWRKY21), transmembrane transporters (OsAAP7A, OsAMT2;1), sugar metabolizing (OsSUS4, α-Gal III) and abiotic stress (OsRCI2-7, SRWD1) genes. Functional data evidences from Arabidopsis heat-shock genes also suggest that OsBIP2 may be associated with thermotolerance of pollen tubes under heat stress conditions. Furthermore, promoters of identified genes were enriched with heat, dehydration, pollen and sugar responsive cis-acting regulatory elements, proposing a common regulatory mechanism might exist in rice for mitigating reproductive stage heat stress. These findings strongly support our results and provide new candidate genes for fast-track development of heat-tolerant rice cultivars.


Assuntos
Resposta ao Choque Térmico/genética , Oryza/genética , Oryza/metabolismo , Locos de Características Quantitativas/genética , Locos de Características Quantitativas/fisiologia , Bases de Dados Genéticas , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Genômica , Temperatura Alta , Oryza/crescimento & desenvolvimento , Fenótipo , Desenvolvimento Vegetal/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas , Reprodução , Estresse Fisiológico/genética , Termotolerância
11.
Nature ; 584(7819): 109-114, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32669710

RESUMO

The size of plants is largely determined by growth of the stem. Stem elongation is stimulated by gibberellic acid1-3. Here we show that internode stem elongation in rice is regulated antagonistically by an 'accelerator' and a 'decelerator' in concert with gibberellic acid. Expression of a gene we name ACCELERATOR OF INTERNODE ELONGATION 1 (ACE1), which encodes a protein of unknown function, confers cells of the intercalary meristematic region with the competence for cell division, leading to internode elongation in the presence of gibberellic acid. By contrast, upregulation of DECELERATOR OF INTERNODE ELONGATION 1 (DEC1), which encodes a zinc-finger transcription factor, suppresses internode elongation, whereas downregulation of DEC1 allows internode elongation. We also show that the mechanism of internode elongation that is mediated by ACE1 and DEC1 is conserved in the Gramineae family. Furthermore, an analysis of genetic diversity suggests that mutations in ACE1 and DEC1 have historically contributed to the selection of shorter plants in domesticated populations of rice to increase their resistance to lodging, and of taller plants in wild species of rice for adaptation to growth in deep water. Our identification of these antagonistic regulatory factors enhances our understanding of the gibberellic acid response as an additional mechanism that regulates internode elongation and environmental fitness, beyond biosynthesis and gibberellic acid signal transduction.


Assuntos
Giberelinas/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/metabolismo , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/metabolismo , Aclimatação , Mutação , Oryza/genética , Reguladores de Crescimento de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Caules de Planta/genética , Locos de Características Quantitativas , Transdução de Sinais
12.
PLoS One ; 15(7): e0236757, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730317

RESUMO

Advancing our understanding of the connections among groundwater, food, and climate is critical to meet global food demands while optimizing water resources usage. However, our understanding of the linkages among groundwater, food, and climate is still limited. Here, we offer a Bayesian framework to simulate crop yield at a regional scale and quantify its relationships and associated uncertainty with climate, groundwater, agricultural, and energy-related variables. We implemented the framework in the rice-producing regions of Louisiana from 1960-2015. To build a parsimonious model, we used a probability-based variable selection approach to detect the key drivers of rice yield. Rice yield increased, groundwater declined, and area planted declined or did not change over 56yrs. The number of irrigation wells, groundwater level, air temperature, and area planted were found to be the key drivers of rice yield. The regression coefficients showed that rice yield was positively related to groundwater level, and negatively related to area planted and the number of irrigation wells. The limited influence of N fertilizer was noted on rice yield for the period when fertilizer data were available. The inverse relationship between rice yield and area planted pointed to the adaption of efficient crop management practices that maintained or increased yield, despite the decline in area planted. The farmers' ability to install irrigation wells during droughts sustained the yields over long-term but not short-term. This decline in rice yield in response to drought over the short-term might explain the negative relation between yield and irrigation wells. Overall, this work highlighted the uncertainty in relationships between rice yield and key drivers and quantified the intimate connection between food and groundwater. This work may have implications for managing two highly competing commodities (i.e., groundwater and food) in agricultural regions.


Assuntos
Teorema de Bayes , Clima , Produtos Agrícolas/crescimento & desenvolvimento , Fertilizantes/análise , Água Subterrânea , Modelos Teóricos , Oryza/crescimento & desenvolvimento , Adaptação Fisiológica , Humanos , Louisiana
13.
Nat Commun ; 11(1): 2819, 2020 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-32499482

RESUMO

Increased grain yield will be critical to meet the growing demand for food, and could be achieved by delaying crop senescence. Here, via quantitative trait locus (QTL) mapping, we uncover the genetic basis underlying distinct life cycles and senescence patterns of two rice subspecies, indica and japonica. Promoter variations in the Stay-Green (OsSGR) gene encoding the chlorophyll-degrading Mg++-dechelatase were found to trigger higher and earlier induction of OsSGR in indica, which accelerated senescence of indica rice cultivars. The indica-type promoter is present in a progenitor subspecies O. nivara and thus was acquired early during the evolution of rapid cycling trait in rice subspecies. Japonica OsSGR alleles introgressed into indica-type cultivars in Korean rice fields lead to delayed senescence, with increased grain yield and enhanced photosynthetic competence. Taken together, these data establish that naturally occurring OsSGR promoter and related lifespan variations can be exploited in breeding programs to augment rice yield.


Assuntos
Genes de Plantas , Variação Genética , Oryza/crescimento & desenvolvimento , Oryza/genética , Regiões Promotoras Genéticas/genética , Alelos , Sequência de Bases , Regulação da Expressão Gênica de Plantas , Endogamia , Fenótipo , Polimorfismo Genético , Locos de Características Quantitativas/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
14.
PLoS One ; 15(6): e0234088, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32559183

RESUMO

Bacterial blight (BB) and fungal blast diseases are the major biotic constraints that limit rice productivity. To sustain yield improvement in rice, it is necessary to developed yield potential of the rice varieties by incorporation of biotic stress resistance genes. Tellahamsa is a well-adapted popular high yielding rice variety in Telangana state, India. However, the variety is highly susceptible to BB and blast. In this study, simultaneous stepwise transfer of genes through marker-assisted backcross breeding (MABB) strategy was used to introgress two major BB (Xa21 and xa13) and two major blast resistance genes (Pi54 and Pi1) into Tellahamsa. In each generation (from F1 to ICF3) foreground selection was done using gene-specific markers viz., pTA248 (Xa21), xa13prom (xa13), Pi54MAS (Pi54) and RM224 (Pi1). Two independent BC2F1 lines of Tellahamsa/ISM (Cross-I) and Tellahamsa/NLR145 (Cross-II) possessing 92% and 94% recurrent parent genome (RPG) respectively were intercrossed to develop ICF1-ICF3 generations. These gene pyramided lines were evaluated for key agro-morphological traits, quality, and resistance against blast at three different hotspot locations as well as BB at two locations. Two ICF3 gene pyramided lines viz., TH-625-159 and TH-625-491 possessing four genes exhibited a high level of resistance to BB and blast. In the future, these improved Tellahamsa lines could be developed as mega varieties for different agro-climatic zones and also as potential donors for different pre-breeding rice research.


Assuntos
Resistência à Doença/genética , Genoma de Planta , Oryza/genética , Doenças das Plantas/genética , DNA de Plantas/metabolismo , Grão Comestível/fisiologia , Marcadores Genéticos , Genótipo , Oryza/crescimento & desenvolvimento , Doenças das Plantas/microbiologia
15.
Nat Commun ; 11(1): 3115, 2020 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-32561756

RESUMO

Reproduction-specific small RNAs are vital regulators of germline development in animals and plants. MicroRNA2118 (miR2118) is conserved in plants and induces the production of phased small interfering RNAs (phasiRNAs). To reveal the biological functions of miR2118, we describe here rice mutants with large deletions of the miR2118 cluster. Our results demonstrate that the loss of miR2118 causes severe male and female sterility in rice, associated with marked morphological and developmental abnormalities in somatic anther wall cells. Small RNA profiling reveals that miR2118-dependent 21-nucleotide (nt) phasiRNAs in the anther wall are U-rich, distinct from the phasiRNAs in germ cells. Furthermore, the miR2118-dependent biogenesis of 21-nt phasiRNAs may involve the Argonaute proteins OsAGO1b/OsAGO1d, which are abundant in anther wall cell layers. Our study highlights the site-specific differences of phasiRNAs between somatic anther wall and germ cells, and demonstrates the significance of miR2118/U-phasiRNA functions in anther wall development and rice reproduction.


Assuntos
Flores/crescimento & desenvolvimento , MicroRNAs/metabolismo , Oryza/crescimento & desenvolvimento , RNA de Plantas/metabolismo , RNA Interferente Pequeno/biossíntese , Proteínas Argonauta/genética , Proteínas Argonauta/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação da Expressão Gênica de Plantas , MicroRNAs/genética , Mutação , Organogênese Vegetal/genética , Oryza/genética , Epiderme Vegetal/crescimento & desenvolvimento , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas
16.
PLoS One ; 15(6): e0233951, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32559220

RESUMO

Genomic prediction (GP) is expected to become a powerful technology for accelerating the genetic improvement of complex crop traits. Several GP models have been proposed to enhance their applications in plant breeding, including environmental effects and genotype-by-environment interactions (G×E). In this study, we proposed a two-step model for plant biomass prediction wherein environmental information and growth-related traits were considered. First, the growth-related traits were predicted by GP. Second, the biomass was predicted from the GP-predicted values and environmental data using machine learning or crop growth modeling. We applied the model to a 2-year-old field trial dataset of recombinant inbred lines of japonica rice and evaluated the prediction accuracy with training and testing data by cross-validation performed over two years. Therefore, the proposed model achieved an equivalent or a higher correlation between the observed and predicted values (0.53 and 0.65 for each year, respectively) than the model in which biomass was directly predicted by GP (0.40 and 0.65 for each year, respectively). This result indicated that including growth-related traits enhanced accuracy of biomass prediction. Our findings are expected to contribute to the spread of the use of GP in crop breeding by enabling more precise prediction of environmental effects on crop traits.


Assuntos
Biomassa , Modelos Genéticos , Oryza/crescimento & desenvolvimento , Oryza/genética , Genoma de Planta , Genômica/métodos , Genótipo , Aprendizado de Máquina , Fenótipo , Melhoramento Vegetal
17.
Ecotoxicol Environ Saf ; 201: 110804, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32502907

RESUMO

Phenanthrene (PHE) is harmful to human health and is difficult to be eliminated from environment. In this study, an aerobic bacterium capable of use PHE as a sole carbon source and energy was isolated and classified as Klebsiella sp. PD3 according to 16S rDNA analysis. The degradation efficiency of PHE reached to about 78.6% after 12 days of incubation with strain PD3. Identification of metabolites formed during PHE degradation process by this strain was carried out by GC-MS. The first degradation step of PHE by PD3 was proposed to generate 1-hydroxy-2-naphthoic acid. Two subsequent different routes for the metabolism of 1-hydroxy-2-naphthoic acid were proposed. Strain PD3 also showed two plant growth promoting properties like phosphate solubilization and ACC deaminase activity. Inoculation with Klebsiella sp. PD3 significantly improved growth performance, biomass production, seed germination rate, photosynthetic capacity, antioxidant levels, relative water content and chlorophyll accumulation in rice (Oryza sativa L.) plants under PHE stress conditions in comparison with non-inoculation treatment. Moreover, PD3-inoculated rice showed lower ROS accumulation, ethylene production, ACC content, ACC oxidase activity and electrolyte leakage under PHE treatment compared to non-inoculated ones. The combination use of rice plants and strain PD3 was also shown to enhance the removal efficiency of PHE from the soil and decline the PHE accumulation in plants. Synergistic use of plants and bacteria with PHE degradation ability and PGPR attributes to remediate the PHE-contaminated soil will be an important and effective way in the phytoremediation of PHE-contaminated soils.


Assuntos
Adaptação Fisiológica , Klebsiella/metabolismo , Oryza/crescimento & desenvolvimento , Fenantrenos/análise , Microbiologia do Solo , Poluentes do Solo/análise , Biodegradação Ambiental , Clorofila/metabolismo , Etilenos/metabolismo , Klebsiella/isolamento & purificação , Oryza/metabolismo , Oryza/microbiologia , Estresse Oxidativo/efeitos dos fármacos , Fenantrenos/metabolismo , Solo/química , Poluentes do Solo/metabolismo
18.
Plant Mol Biol ; 103(4-5): 545-560, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32504260

RESUMO

KEY MESSAGE: OsGTγ-2, a trihelix transcription factor, is a positive regulator of rice responses to salt stress by regulating the expression of ion transporters. Salinity stress seriously restricts rice growth and yield. Trihelix transcription factors (GT factors) specifically bind to GT elements and play a diverse role in plant morphological development and responses to abiotic stresses. In our previous study, we found that the GT-1 element (GAAAAA) is a key element in the salinity-induced OsRAV2 promoter. Here, we identified a rice OsGTγ family member, OsGTγ-2, which directly interacted with the GT-1 element in the OsRAV2 promoter. OsGTγ-2 specifically targeted the nucleus, was mainly expressed in roots, sheathes, stems and seeds, and was induced by salinity, osmotic and oxidative stresses and abscisic acid (ABA). The seed germination rate, seedling growth and survival rate under salinity stress was improved in OsGTγ-2 overexpressing lines (PZmUbi::OsGTγ-2). In contrast, CRISPR/Cas9-mediated OsGTγ-2 knockout lines (osgtγ-2) showed salt-hypersensitive phenotypes. In response to salt stress, different Na+ and K+ acclamation patterns were observed in PZmUbi::OsGTγ-2 lines and osgtγ-2 plants were observed. The molecular mechanism of OsGTγ-2 in rice salt adaptation was also investigated. Several major genes responsible for ion transporting, such as the OsHKT2; 1, OsHKT1; 3 and OsNHX1 were transcriptionally regulated by OsGTγ-2. A subsequent yeast one-hybrid assay and EMSA indicated that OsGTγ-2 directly interacted with the promoters of OsHKT2; 1, OsNHX1 and OsHKT1; 3. Taken together, these results suggest that OsGTγ-2 is an important positive regulator involved in rice responses to salt stress and suggest a potential role for OsGTγ-2 in regulating salinity adaptation in rice.


Assuntos
Aclimatação/fisiologia , Proteínas de Ligação a DNA/metabolismo , Oryza/fisiologia , Estresse Salino/fisiologia , Tolerância ao Sal/genética , Fatores de Transcrição/metabolismo , Ácido Abscísico/metabolismo , Aclimatação/genética , Adaptação Fisiológica , Sistemas CRISPR-Cas , Proteínas de Transporte de Cátions/metabolismo , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica de Plantas , Oryza/genética , Oryza/crescimento & desenvolvimento , Desenvolvimento Vegetal , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Salinidade , Plântula/genética , Sementes/metabolismo , Sódio/metabolismo , Trocadores de Sódio-Hidrogênio/metabolismo , Estresse Fisiológico/genética , Simportadores/metabolismo , Fatores de Transcrição/genética
19.
Mol Genet Genomics ; 295(5): 1211-1226, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32506235

RESUMO

North Eastern part of India such as Assam is inundated by flood every year where the farmers are forced to grow the traditional tall deep-water rice. Genetic improvement of this type of rice is slow because of insufficient knowledge about their genetic architecture and population structure. In the present investigation, the genetic diversity architecture of 94 deep-water rice genotypes of Assam and association mapping strategy was, for the first time, applied to determine the significant SNPs and genes for deep-water rice. These genotypes are known for their unique elongation ability under deep-water condition. The anaerobic germination (AG) related trait-associated genes identified here can provide affluent resources for rice breeding especially in flood-prone areas. We investigated the genome-wide association studies (GWAS) using 50 K rice genic SNP chip across 94 deep-water rice genotypes collected from different flood-prone districts/villages of Assam. Population structure and diversity analysis revealed that these genotypes were stratified into four sub-populations. Using GWAS approach, 20 significant genes were identified and found to be associated with AG-related traits. Of them, two most relevant genes (OsXDH1and SSXT) have been identified which explain phenotypic variability (R2 > 20%) in the population. These genes were located in Chr 3 (LOC_Os03g31550) which encodes for enzyme xanthine dehydrogenase 1(OsXDH1) and in Chr 12 (LOC_Os12g31350) which encodes for SSXT family protein. Both of these genes were found to be associated with anaerobic response index (increase in the coleoptile length under water in anaerobic condition with respect to control), respectively. Interestingly, OsXDH1is involved in purine catabolism pathway and acts as a scavenger of reactive oxygen species in plants, whereas SSXT is GRF1-interacting factor 3. These two candidate genes associated with AG of deep-water rice have been found to be reported for the first time. Thus, this study provides a greater resource for breeders not only for improvement of deep-water rice, but also for AG tolerant variety useful for direct-seeded rice in flood-affected areas.


Assuntos
Estudo de Associação Genômica Ampla/métodos , Oryza/crescimento & desenvolvimento , Polimorfismo de Nucleotídeo Único , Locos de Características Quantitativas , Mapeamento Cromossômico , Germinação , Índia , Análise de Sequência com Séries de Oligonucleotídeos , Oryza/genética , Fenótipo , Melhoramento Vegetal , Proteínas de Plantas/genética
20.
Proc Natl Acad Sci U S A ; 117(28): 16649-16659, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32586957

RESUMO

Low availability of nitrogen (N) is often a major limiting factor to crop yield in most nutrient-poor soils. Arbuscular mycorrhizal (AM) fungi are beneficial symbionts of most land plants that enhance plant nutrient uptake, particularly of phosphate. A growing number of reports point to the substantially increased N accumulation in many mycorrhizal plants; however, the contribution of AM symbiosis to plant N nutrition and the mechanisms underlying the AM-mediated N acquisition are still in the early stages of being understood. Here, we report that inoculation with AM fungus Rhizophagus irregularis remarkably promoted rice (Oryza sativa) growth and N acquisition, and about 42% of the overall N acquired by rice roots could be delivered via the symbiotic route under N-NO3 - supply condition. Mycorrhizal colonization strongly induced expression of the putative nitrate transporter gene OsNPF4.5 in rice roots, and its orthologs ZmNPF4.5 in Zea mays and SbNPF4.5 in Sorghum bicolor OsNPF4.5 is exclusively expressed in the cells containing arbuscules and displayed a low-affinity NO3 - transport activity when expressed in Xenopus laevis oocytes. Moreover, knockout of OsNPF4.5 resulted in a 45% decrease in symbiotic N uptake and a significant reduction in arbuscule incidence when NO3 - was supplied as an N source. Based on our results, we propose that the NPF4.5 plays a key role in mycorrhizal NO3 - acquisition, a symbiotic N uptake route that might be highly conserved in gramineous species.


Assuntos
Proteínas de Transporte de Ânions/metabolismo , Glomeromycota/fisiologia , Micorrizas/fisiologia , Nitrogênio/metabolismo , Oryza/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Transporte de Ânions/genética , Regulação da Expressão Gênica de Plantas , Nitratos/metabolismo , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/microbiologia , Proteínas de Plantas/genética , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Sorghum/genética , Sorghum/metabolismo , Sorghum/microbiologia , Zea mays/genética , Zea mays/metabolismo , Zea mays/microbiologia
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