Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 368
Filtrar
Mais filtros










Intervalo de ano de publicação
1.
Cytogenet Genome Res ; 160(2): 100-109, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32146470

RESUMO

Chloroplasts and mitochondria are semi-autonomous organelles and have their own genomes (cytoplasmic genomes). Physical radiations (e.g., γ-rays) have been widely used in artificial mutation induction for plant germplasm enhancement and for breeding new cultivars. However, little is known at the genomic level about which kind of cytoplasmic mutations and/or characteristics could be induced in plants. The present study aimed to investigate the type, number, and distribution of inheritable cytoplasmic mutations induced by γ-rays in rice (Oryza sativa L.). Six plants were selected from the 2nd generation (M2) populations after γ-ray (137Cs) irradiation of the rice cultivar Nipponbare, 2 each for the 3 irradiation doses (150, 250, and 350 Gy), and their genomes were sequenced on an Illumina platform. Together with the whole-genome sequencing data of 3 external Nipponbare control plants, single-base substitutions (SBSs) and insertions/deletions (InDels) in chloroplast (cp) and mitochondrial (mt) genomes were identified and analyzed in-depth using bioinformatic tools. The majority of SBSs and InDels identified were background mutations in the 6 M2 plants, and the number of induced mutations varied greatly among the plants. Most induced mutations were present in a heterogeneous state, reflecting the fact that multiple cp and mt copies existed in the progenitor cells. The induced mutations were distributed in different genomic regions in the 6 M2 plants, including exonic regions, but none of them was predicted to cause nonsynonymous mutations or frameshifts. Our study thus revealed, at the genomic level, characteristics of cytoplasmic mutations induced by γ-rays in rice.


Assuntos
Raios gama/efeitos adversos , Mutação , Oryza/efeitos da radiação , Sequenciamento Completo do Genoma/métodos , Cloroplastos/genética , Cloroplastos/efeitos da radiação , Genoma de Planta/efeitos da radiação , Sequenciamento de Nucleotídeos em Larga Escala , Mitocôndrias/genética , Mitocôndrias/efeitos da radiação , Oryza/genética , Proteínas de Plantas/genética , Proteínas de Plantas/efeitos da radiação , Sementes/genética , Sementes/efeitos da radiação
2.
PLoS One ; 14(12): e0226633, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31846481

RESUMO

Electron-beam irradiation (EBI) is a cold sterilization technology used in the irradiation processing of food, including rice. Herein, the effects of EBI on the swelling power, color, pasting, and sensory properties of white rice after short-term storage were analyzed. Samples were electron-beam irradiated at 0, 2, 4, 6, or 8 kGy and stored at 25 °C or 37 °C for up to 75 days. Results showed that swelling power and major pasting viscosities (including peak, breakdown, and setback viscosities) at both storage temperatures decreased with increased irradiation dose. Negative correlations were also observed between the major viscosities of pasting properties and irradiation dose at both storage temperatures. During sensory evaluation, extremely low scores for rice hardness, appearance, taste, and overall acceptability were obtained for rice subjected to high EBI dose (>4 kGy). However, rice stored at 37 °C showed lower performance than rice at 25 °C in terms of the abovementioned parameters. By contrast, the sensory properties at irradiation doses between 2 and 4 kGy were better than those of the control group at both storage temperatures. All these findings indicated the potential of low-dose (<4 kGy) EBI as pretreatment for improving the quality of white rice during storage.


Assuntos
Irradiação de Alimentos/métodos , Armazenamento de Alimentos/métodos , Oryza/efeitos da radiação , Controle de Qualidade , Amido/efeitos da radiação , Relação Dose-Resposta à Radiação , Elétrons , Armazenamento de Alimentos/normas , Viscosidade
3.
BMC Plant Biol ; 19(1): 462, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31675987

RESUMO

BACKGROUND: Flowering time is one of the most important agronomic characteristics that ultimately determine yield potential and eco-geographical adaptation in crops. Ghd8 and Ghd7, two major flowering genes, have similar functions and large pleiotropic effects in controlling the heading date, plant height and grain yield of rice. However, these gene interactions at the genetic and molecular levels have not been determined to date. RESULTS: In this study, we investigated the genetic interaction between Ghd8 and Ghd7 by using a set of near-isogenic lines and a panel of natural germplasm accessions in rice. We found that Ghd8 affected multiple agronomic traits in a functional Ghd7-dependent manner. Both functional Ghd8 and Ghd7 are pivotal for rice photoperiod sensitivity controlled by Hd1 and Hd3a. GHD8 could form a heterotrimeric complex with HD1 and OsHAP5b to activate the transcription of Ghd7 by binding directly to the promoter region of Ghd7, which contains the CCAAT-box motif. CONCLUSIONS: The results of this study help to elucidate the genetic and molecular bases of Ghd8 and Ghd7 interactions, indicating that Ghd8 acts upstream of Ghd7 to activate its transcription, which inhibits Hd3a expression and thus affects flowering time and rice adaptation.


Assuntos
Flores/crescimento & desenvolvimento , Oryza/genética , Fotoperíodo , Proteínas de Plantas/genética , Aclimatação/genética , Adaptação Biológica , Flores/genética , Flores/efeitos da radiação , Oryza/efeitos da radiação , Fenótipo , Proteínas de Plantas/metabolismo
4.
Int J Mol Sci ; 20(18)2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31491955

RESUMO

Japonica and indica are two important subspecies in cultivated Asian rice. Irradiation is a classical approach to induce mutations and create novel germplasm. However, little is known about the differential response between japonica and indica rice after γ radiation. Here, we utilized the RNA sequencing and Weighted Gene Co-expression Network Analysis (WGCNA) to compare the transcriptome differences between japonica Nipponbare (NPB) and indica Yangdao6 (YD6) in response to irradiation. Japonica subspecies are more sensitive to irradiation than the indica subspecies. Indica showed a higher seedling survival rate than japonica. Irradiation caused more extensive DNA damage in shoots than in roots, and the severity was higher in NPB than in YD6. GO and KEGG pathway analyses indicate that the core genes related to DNA repair and replication and cell proliferation are similarly regulated between the varieties, however the universal stress responsive genes show contrasting differential response patterns in japonica and indica. WGCNA identifies 37 co-expressing gene modules and ten candidate hub genes for each module. This provides novel evidence indicating that certain peripheral pathways may dominate the molecular networks in irradiation survival and suggests more potential target genes in breeding for universal stress tolerance in rice.


Assuntos
Raios gama , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Redes Reguladoras de Genes , Oryza/genética , Oryza/efeitos da radiação , Transcriptoma , Biologia Computacional/métodos , Dano ao DNA/genética , Perfilação da Expressão Gênica , Ontologia Genética , Tolerância a Radiação/genética , Plântula/genética , Plântula/efeitos da radiação
5.
Plant Sci ; 286: 1-6, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31300135

RESUMO

The excessive and harmful light energy absorbed by the photosystem (PS) II of higher plants is dissipated as heat through a protective mechanism termed non-photochemical quenching (NPQ) of chlorophyll fluorescence. PsbS-knock-out (KO) mutants lack the trans-thylakoid proton gradient (ΔpH)-dependent part of NPQ. To elucidate the molecular mechanism of NPQ, we investigated its dependency on oxygen. The development of NPQ in wild-type (WT) rice under low-oxygen (LO) conditions was reduced to more than 50% of its original value. However, under high-oxygen (HO) conditions, the NPQ of both WT and PsbS-KO mutants recovered. Moreover, WT and PsbS-KO mutant leaves infiltrated with the ΔpH dissipating uncoupler nigericin showed increased NPQ values under HO conditions. The experiments using intact chloroplasts and protoplasts of Arabidopsis thaliana supported that the LO effects observed in rice leaves were not due to carbon dioxide deficiency. There was a noticeable 90% reduction in the half-time of P700 oxidation rate in LO-treated leaves compared with that of WT control leaves, but the HO treatment did not significantly change the half-time of P700 oxidation rate. Overall, the results obtained here indicate that the stroma of the PsbS-KO plants could be potentially under O2 deficiency. Because the functions of PsbS in rice leaves are likely to be similar to those in other higher plants, our findings offer novel insights into the role of oxygen in the development of NPQ.


Assuntos
Adaptação Fisiológica/efeitos da radiação , Arabidopsis/metabolismo , Oryza/metabolismo , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Arabidopsis/efeitos da radiação , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Oryza/efeitos da radiação , Complexo de Proteína do Fotossistema II/genética , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Protoplastos/metabolismo , Protoplastos/efeitos da radiação
6.
Plant Cell Physiol ; 60(10): 2307-2318, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31290959

RESUMO

Chlorophyll biosynthesis plays essential roles in photosynthesis and plant growth in response to environmental conditions. The accumulation of excess chlorophyll biosynthesis intermediates under light results in the production of reactive oxygen species and oxidative stress. In this study, we identified a rice (Oryza sativa) mutant, oxidation under photoperiod (oxp), that displayed photobleached lesions on its leaves, reduced growth and decreased chlorophyll content during light/dark cycles or following a dark-to-light transition. The oxp mutant accumulated more chlorophyll precursors (5-aminolevulinic acid and protochlorophyllide) than the wild type in the dark, and more singlet oxygen following light exposure. Several singlet-oxygen-responsive genes were greatly upregulated in oxp, whereas the expression patterns of OsPORA and OsPORB, two genes encoding the chlorophyll biosynthesis enzyme NADPH:protochlorop hyllide oxidoreductase, were altered in de-etiolated oxp seedlings. Molecular and complementation studies revealed that oxp is a loss-of-function mutant in LOC_Os01g32730, a homolog of FLUORESCENT (FLU) in Arabidopsis thaliana. Rice PHYTOCHROME-INTERACTING FACTOR-LIKE14 (OsPIL14) transcription factor directly bound to the OsFLU1 promoter and activated its expression. Dark-grown transgenic rice seedlings overexpressing OsPIL14 accumulated more chlorophyll and turned green faster than the wild type upon light illumination. Thus, OsFLU1 is an important regulator of chlorophyll biosynthesis in rice.


Assuntos
Proteínas de Arabidopsis/genética , Oryza/genética , Proteínas de Plantas/metabolismo , Transdução de Sinais/efeitos da radiação , Ácido Aminolevulínico/metabolismo , Clorofila/biossíntese , Estiolamento , Luz , Mutação , Oryza/fisiologia , Oryza/efeitos da radiação , Estresse Oxidativo , Fotoperíodo , Fotossíntese , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas/genética , Protoclorifilida/metabolismo , Plântula/genética , Plântula/fisiologia , Plântula/efeitos da radiação , Oxigênio Singlete/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
7.
J Food Sci ; 84(8): 2222-2227, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31339565

RESUMO

The conventional prolonged parboiling process results in high operation cost and grain darkening, which may limit consumption. Moreover, residue generation by rice industries is another challenge. The objective of this study was to evaluate the use of microwave irradiation during soaking and gelatinization stages of parboiling rice. Processing time, colorimetric profile, broken and nongelatinized grains, sucrose and glucose content, free 5-hydroxymethyl-2-furfural, and residual phosphorus were evaluated. As the soaking and gelatinization times during microwave treatments increased, the colorimetric parameters increased; however, the values were lower than those with the conventional process. Regardless of soaking time, a decrease in broken and nongelatinized grains was obtained by using the lowest steaming time (5 min). Additionally, lower residual phosphorus content was found in soaking water (10 and 20 min) when using microwave irradiation. Under favorable conditions, a reduction in the levels of broken and nongelatinized grains, residual phosphorus, and color changes was observed, indicating that microwave irradiation may be more beneficial than conventional parboiling. PRACTICAL APPLICATION: Parboiling requires a high volume of water and soaking time, which leads to high costs, underutilization of infrastructures, and high residue in the water after processing. The rapid parboiling process involves the use of microwaves during the soaking and gelatinization stages. The main advantages of the microwave parboiling process include reduced processing time, ranging from 83% to 95%, higher gelatinization, greater yield, reduced darkening, and reduced residual phosphorus in the effluents by 60%. This report can aid industries in streamlining their processes, thereby providing a high-quality, lower cost, and environmentally safe product.


Assuntos
Manipulação de Alimentos/métodos , Oryza/química , Oryza/efeitos da radiação , Fósforo/análise , Águas Residuárias/análise , Culinária , Temperatura Alta , Micro-Ondas , Sementes/química , Sementes/efeitos da radiação
8.
Plant Mol Biol ; 100(1-2): 133-149, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30843130

RESUMO

KEY MESSAGE: The OsPLS2 locus was isolated and cloned by map-based cloning that encodes a Upf1-like helicase. Disruption of OsPLS2 accelerated light-dependent leaf senescence in the rice mutant of ospls2. Leaf senescence is a very complex physiological process controlled by both genetic and environmental factors, however its underlying molecular mechanisms remain elusive. In this study, we report a novel Oryza sativa premature leaf senescence mutant (ospls2). Through map-based cloning, a G-to-A substitution was determined at the 1st nucleotide of the 13th intron in the OsPLS2 gene that encodes a Upf1-like helicase. This mutation prompts aberrant splicing of OsPLS2 messenger and consequent disruption of its full-length protein translation, suggesting a negative role of OsPLS2 in regulating leaf senescence. Wild-type rice accordingly displayed a progressive drop of OsPSL2 protein levels with age-dependent leaf senescence. Shading and light filtration studies showed that the ospls2 phenotype, which was characteristic of photo-oxidative stress and reactive oxygen species (ROS) accumulation, was an effect of irritation by light. When continuously exposed to far-red light, exogenous H2O2 and/or abscisic acid (ABA), the ospls2 mutant sustained hypersensitive leaf senescence. In consistence, light and ROS signal pathways in ospls2 were activated by down-regulation of phytochrome genes, and up-regulation of PHYTOCHROME-INTERACTING FACTORS (PIFs) and WRKY genes, all promoting leaf senescence. Together, these data indicated that OsPLS2 played an essential role in leaf senescence and its disruption triggered light-dependent leaf senescence in rice.


Assuntos
DNA Helicases/genética , Genes de Plantas , Luz , Oryza/crescimento & desenvolvimento , Oryza/genética , Folhas de Planta/crescimento & desenvolvimento , Proteínas de Plantas/genética , Ácido Abscísico/metabolismo , Sequência de Aminoácidos , Antioxidantes/metabolismo , DNA Helicases/química , DNA Helicases/metabolismo , Regulação da Expressão Gênica de Plantas , Mutação/genética , Oryza/enzimologia , Oryza/efeitos da radiação , Fenótipo , Fotossíntese/genética , Folhas de Planta/genética , Folhas de Planta/efeitos da radiação , Folhas de Planta/ultraestrutura , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fatores de Tempo
9.
Planta ; 250(1): 105-114, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30927053

RESUMO

MAIN CONCLUSION: Rice phytochrome-interacting factor-like protein OsPIL15 regulates tiller angle through light and gravity signals in rice. Tiller angle of cereal crops is a key agronomic trait that contributes to grain production. An understanding of how tiller angle is controlled is helpful for achieving ideal plant architecture to improve grain yield. Phytochrome-interacting factors (PIFs) are known to regulate seed germination, seedling skotomorphogenesis, shade avoidance, and flowering in Arabidopsis thaliana. Here, we report that OsPIL15 is, indeed, a rice PIF that negatively regulates tiller angle. Dominant-negative OsPIL15 plants displayed a larger tiller angle, which was associated with reduced shoot gravitropism. Phytochrome B (phyB) is the main photoreceptor perceiving the low red:far-red ratio of shade light. Compared with wild-type rice plants, loss-of-function phyB plants and OsPIL15-overexpressing plants showed smaller tiller angles and enhanced shoot gravitropism. In addition, more OsPIL15 protein accumulated in phyB plants than in wild-type plants. Light regulates the level of the OsPIL15 protein negatively, depending on phyB partially. We propose that OsPIL15 integrates light and gravity signals to regulate tiller angle in rice.


Assuntos
Regulação da Expressão Gênica de Plantas , Gravitropismo/genética , Oryza/fisiologia , Fitocromo/metabolismo , Proteínas de Plantas/metabolismo , Gravitropismo/efeitos da radiação , Luz , Oryza/genética , Oryza/crescimento & desenvolvimento , Oryza/efeitos da radiação , Proteínas de Plantas/genética , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/fisiologia , Brotos de Planta/efeitos da radiação , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Plântula/efeitos da radiação
10.
Mol Plant ; 12(2): 199-214, 2019 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-30639120

RESUMO

Over the past few years, three photorespiratory bypasses have been introduced into plants, two of which led to observable increases in photosynthesis and biomass yield. However, most of the experiments were carried out using Arabidopsis under controlled environmental conditions, and the increases were only observed under low-light and short-day conditions. In this study, we designed a new photorespiratory bypass (called GOC bypass), characterized by no reducing equivalents being produced during a complete oxidation of glycolate into CO2 catalyzed by three rice-self-originating enzymes, i.e., glycolate oxidase, oxalate oxidase, and catalase. We successfully established this bypass in rice chloroplasts using a multi-gene assembly and transformation system. Transgenic rice plants carrying GOC bypass (GOC plants) showed significant increases in photosynthesis efficiency, biomass yield, and nitrogen content, as well as several other CO2-enriched phenotypes under both greenhouse and field conditions. Grain yield of GOC plants varied depending on seeding season and was increased significantly in the spring. We further demonstrated that GOC plants had significant advantages under high-light conditions and that the improvements in GOC plants resulted primarily from a photosynthetic CO2-concentrating effect rather than from improved energy balance. Taken together, our results reveal that engineering a newly designed chloroplastic photorespiratory bypass could increase photosynthetic efficiency and yield of rice plants grown in field conditions, particularly under high light.


Assuntos
Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Engenharia Genética , Luz , Oryza/citologia , Oryza/genética , Fotossíntese/genética , Dióxido de Carbono/metabolismo , Respiração Celular/genética , Respiração Celular/efeitos da radiação , Metabolismo Energético/genética , Metabolismo Energético/efeitos da radiação , Oryza/metabolismo , Oryza/efeitos da radiação , Fenótipo , Fotossíntese/efeitos da radiação , Plantas Geneticamente Modificadas
11.
Photosynth Res ; 140(3): 321-335, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30694432

RESUMO

Mechanisms involving ammonium toxicity, excess light, and photosynthesis are scarcely known in plants. We tested the hypothesis that high NH4+ supply in presence of high light decreases photosynthetic efficiency of rice plants, an allegedly tolerant species. Mature rice plants were previously supplied with 10 mM NH4+ or 10 mM NO3- and subsequently exposed to 400 µmol m-2 s-1 (moderate light-ML) or 2000 µmol m-2 s-1 (high light-HL) for 8 h. HL greatly stimulated NH4+ accumulation in roots and in a minor extent in leaves. These plants displayed significant delay in D1 protein recovery in the dark, compared to nitrate-supplied plants. These responses were related to reduction of both PSII and PSI quantum efficiencies and induction of non-photochemical quenching. These changes were also associated with higher limitation in the donor side and lower restriction in the acceptor side of PSI. This later response was closely related to prominent decrease in stomatal conductance and net CO2 assimilation that could have strongly affected the energy balance in chloroplast, favoring ATP accumulation and NPQ induction. In parallel, NH4+ induced a strong increase in the electron flux to photorespiration and, inversely, it decreased the flux to Rubisco carboxylation. Overall, ammonium supply negatively interacts with excess light, possibly by enhancing ammonium transport towards leaves, causing negative effects on some photosynthetic steps. We propose that high ammonium supply to rice combined with excess light is capable to induce strong delay in D1 protein turnover and restriction in stomatal conductance, which might have contributed to generalized disturbances on photosynthetic efficiency.


Assuntos
Compostos de Amônio/toxicidade , Oryza/fisiologia , Cloroplastos/metabolismo , Metabolismo Energético , Luz , Oryza/efeitos da radiação , Fotossíntese/efeitos dos fármacos , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Raízes de Plantas/fisiologia , Raízes de Plantas/efeitos da radiação , Ribulose-Bifosfato Carboxilase/metabolismo
12.
Radiat Res ; 191(2): 189-200, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30499385

RESUMO

MicroRNAs (miRNAs) are a non-coding regulatory RNAs that play significant roles in plant growth and development, especially in the stress response. Low-energy ion radiation, a type of environmental stress, can cause multiple biological effects. To understand the roles of miRNAs in response to low-energy N+ ion radiation in Oryza sativa, high-throughput sequencing of small RNAs was carried out to detect the expression of miRNAs in the shoots of the rice after 2 × 1017 N+/cm2 irradiation. The differentially expressed 28 known miRNAs were identified, 17 of these identified miRNAs were validated by real-time quantitative fluorescent PCR (q-PCR), including 9 up-regulated miRNAs (miR1320-3p, miR1320-5p, miR156b-3p, miR156c-5p, miR156c-3p/g-3p, miR1561-5p, miR398b and miR6250) and 8 down-regulated miRNAs (miR156a/e/i, miR156k, miR160f-5p, miR166j-5p, miR1846e and miR399d). In addition, 45 novel radiationresponsive miRNAs were predicted, and 8 of them were verified by q-PCR. The target genes of radiation-responsive miRNAs were predicted and gene function enrichment analysis was performed with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The expression of 9 targets of 4 known miRNA families (miR156, miR399, miR1320 and miR398) and 2 targets of 2 novel miRNAs were quantified by q-PCR, and a strong negative regulation relation between miRNAs and their targets were observed. Those targets including SQUAMOSA promoterbinding-like protein (SPL) genes, copper/zinc superoxide dismutase (Cu/Zn-SOD), copper chaperone for SOD (CCS1) and electron transporter/ heat-shock protein binding protein (HSP), which are involved in growth and defense against various stresses, especially associated with reactive oxygen species (ROS) scavenging. This work provides important information for understanding the ROS generation and elimination mechanisms closely related to miRNAs in rice seedlings after low-energy N+ radiation exposure.


Assuntos
MicroRNAs/fisiologia , Nitrogênio/metabolismo , Oryza/efeitos da radiação , MicroRNAs/genética , MicroRNAs/efeitos da radiação , Oryza/genética , RNA de Plantas/genética , RNA de Plantas/fisiologia , RNA de Plantas/efeitos da radiação , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Regulação para Cima
13.
Photosynth Res ; 139(1-3): 107-121, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30456488

RESUMO

Non-photochemical quenching (NPQ) of the excited state of chlorophyll a is a major photoprotective mechanism plants utilize to survive under high light. Here, we report the impact of long-term light quality treatment on photosynthetic properties, especially NPQ in rice. We used three LED-based light regimes, i.e., red (648-672 nm), blue (438-460 nm), and "warm" white light (529-624 nm), with the incident photon flux density of 300 µmol photons m-2 s-1, the difference in the absorbed photon flux densities by leaves grown under different light quality being less than 7%. Our results show that blue light, as compared to white light, induced a significant decrease in Fv/Fm, a decreased rate of reduction of P700+ after P700 was completely oxidized; furthermore, blue light also induced higher NPQ with an increased initial speed of NPQ induction, which corresponds to the qE component of NPQ, and a lower maximum quantum yield of PSII, i.e., Y(II). In contrast, rice grown under long-term red light showed decreased Y(II) and increased NPQ, but with no change in Fv/Fm. Furthermore, we found that rice grown under either blue or red light showed decreased transcript abundance of both catalase and ascorbate peroxidase, together with an increased H2O2 content, as compared to rice grown under white light. All these data suggest that even under a moderate incident light level, rice grown under blue or red light led to compromised antioxidant system, which contributed to decreased quantum yield of photosystem II and increased NPQ.


Assuntos
Luz , Oryza/metabolismo , Oryza/fisiologia , Fotossíntese/fisiologia , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema II/metabolismo , Clorofila A/metabolismo , Oryza/efeitos da radiação , Oxirredução/efeitos da radiação , Folhas de Planta/metabolismo
14.
Plant Sci ; 278: 96-106, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30471734

RESUMO

Silicon (Si) enhances the resistance of rice to biotic and abiotic stress. In rice, the accumulation of Si is controlled by the low silicon rice 1 (Lsi1) gene; overexpression of Lsi1 (Lsi1-OX) increases Si uptake and accumulation, while the reverse is observed in Lsi1-RNA interference (Lsi1-RNAi) transgenic rice. When the two transgenic rice lines and wild-type (WT) rice were exposed to ultraviolet (UV)-B radiation, the Lsi1-OX or Lsi1-RNAi rice showed differential microRNA (miRNA) expression, compared to WT rice. These miRNAs were predicted to target genes involved in light signal transduction and cell detoxification. The greatest capacities of ascorbate peroxidase, superoxide dismutase, peroxidase, and phenylalanine ammonia lyase (PAL) and highest contents of phenolics, flavonoids, and proline were found in Lsi1-OX rice, followed by WT rice and Lsi1-RNAi transgenic rice. A further comparison of the transcript levels of individual PAL genes revealed that the expression of PAL2-2 (Os02g0626400) was positively regulated by Lsi1. Our results demonstrate that Lsi1 overexpression or interference causes changes in both miRNA expression and antioxidant capacity in rice, and therefore modulates rice tolerance to UV-B radiation. Furthermore, we demonstrated that PAL2-2 was positively regulated by Lsi1 during this process.


Assuntos
Antioxidantes/metabolismo , Oryza/genética , Proteínas de Plantas/fisiologia , Flavonoides/metabolismo , Transdução de Sinal Luminoso/genética , MicroRNAs/metabolismo , Oryza/metabolismo , Oryza/efeitos da radiação , Fenóis/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/efeitos da radiação , Interferência de RNA
15.
Photosynth Res ; 140(1): 51-63, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30448978

RESUMO

One of the main limitations of rice yield in regions of high productive performance is the light-use efficiency (LUE). LUE can be determined at the whole-plant level or at the photosynthetic apparatus level (quantum yield). Both vary according to the intensity and spectral quality of light. The aim of this study was to analyze the cultivar dependence regarding LUE at the plant level and quantum yield using four rice cultivars and four light environments. To achieve this, two in-house Light Systems were developed: Light System I which generates white light environments (spectral quality of 400-700 nm band) and Light System II which generates a blue-red light environment (spectral quality of 400-500 nm and 600-700 nm bands). Light environment conditioned the LUE and quantum yield in PSII of all evaluated cultivars. In white environments, LUE decreased when light intensity duplicated, while in blue-red environments no differences on LUE were observed. Energy partition in PSII was determined by the quantum yield of three de-excitation processes using chlorophyll fluorescence parameters. For this purpose, a quenching analysis followed by a relaxation analysis was performed. The damage of PSII was only increased by low levels of energy in white environments, leading to a decrease in photochemical processes due to the closure of the reaction centers. In conclusion, all rice cultivars evaluated in this study were sensible to low levels of radiation, but the response was cultivar dependent. There was not a clear genotypic relation between LUE and quantum yield.


Assuntos
Metabolismo Energético , Oryza/fisiologia , Fotossíntese/efeitos da radiação , Luz , Oryza/efeitos da radiação , Processos Fotoquímicos , Fótons , Especificidade da Espécie
16.
New Phytol ; 222(1): 349-365, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30449034

RESUMO

High light and high temperature (HLHT) stress may become more frequent and severe as the climate changes, affecting crop growth and resulting in reduced production. However, the mechanism of the response to HLHT stress in rice is not yet fully understood. In the present study, we screened a rice mutant library using HLHT conditions and isolated an HLHT-sensitive mutant, local lesions 1 (ls1), which showed decreased pigment contents, defective stomata and chloroplasts, and a local lesions phenotype under HLHT. We characterized and cloned LS1 by map-based cloning and genetic complementation. LS1 encodes the A subunit of the RNase H2 complex (RNASEH2A). Terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and comet assays indicated that mutation of LS1 led to severe DNA damage under HLHT stress. Furthermore, we found excessive reactive oxygen species (ROS) accumulation in the ls1 mutant under HLHT stress. Exogenous antioxidants eased the local lesions phenotype of the ls1 mutant under HLHT. DNA damage caused by HLHT stress induces ROS accumulation, which causes the injury and apoptosis of leaf cells in the ls1 mutant. These results enhance our understanding of the regulatory mechanism in the response to HLHT stress in higher plants.


Assuntos
Dano ao DNA , Luz , Mutação/genética , Oryza/metabolismo , Oryza/efeitos da radiação , Proteínas de Plantas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Temperatura , Antioxidantes/metabolismo , Sequência de Bases , Morte Celular/efeitos da radiação , Forma Celular/efeitos da radiação , Clorofila/metabolismo , Cloroplastos/metabolismo , Cloroplastos/efeitos da radiação , Cloroplastos/ultraestrutura , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Fenótipo , Folhas de Planta/citologia , Folhas de Planta/metabolismo , Folhas de Planta/ultraestrutura , Proteínas de Plantas/genética , Subunidades Proteicas/metabolismo , Ribonucleases/metabolismo , Frações Subcelulares/metabolismo
17.
Hereditas ; 156: 36, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31889942

RESUMO

Background: Heading time is an important trait for regional and seasonal adaptabilities in rice, and is controlled by genetic factors in relation with environmental factors, mainly day length and temperature. The following genes controlling heading were examined for their responses to six different environmental conditions involving different day lengths using five early near-isogenic lines (NILs) of T65-R and three late NILs of T65wx: two earliness genes, Ef1 and Efx controlling basic vegetative phase (BVG), and m-Ef1, the enhancer to the former gene; and two lateness genes, Se1-pat(t) and se-pat controlling photo-sensitivity and BVG, respectively. T65-R and T65-T were different accessions of Taichung 65. T65wx is a NIL of T65-T carrying wx. Results: The five early NILs of T65-R were in the order of ER50 (Ef1, Efx, m-Ef1) < ER40 (Ef1, m-Ef1) ≤ ER20 (Ef1, Efx) < ER1 (Ef1) ≤ ER21 (Efx) < T65-R regarding days to heading (DTH) under two spring-sowing and one summer-sowing paddy field (PF) conditions. The three late NILs of T65wx were in the order of LF3 (Se1-pat(t)) ≤ LF2 (Se1-pat(t), se-pat) ≤ T65wx < LF1 (se-pat) under two short-day conditions (10-h photoperiod condition with artificial-light and natural short-day condition from autumn to winter). The NILs and T65wx were in the order of T65wx < LF3 < LF1 < LF2 under the two spring-sowing PF (long day) conditions. T65-R (Ac-ef1) was 2.8 or 5.1 days earlier in DTH than T65-T (ac-ef1) under the two spring-sowing PF conditions. However, T65-R was 19 and 10 days earlier than T65-T under the two short-day conditions. Conclusions: Earliness gene(s) and their combinations reduced DTH regardless of photoperiod lengths. Se1-pat(t) increased DTH under long-day conditions but decreased it under short-day conditions, while se-pat elongated DTH under both short-day and long-day conditions indicating that se-pat is responsible for BVG. The se-pat increased DTH by adding its effect over that of Se1-pat(t) under long-day conditions. However, this increasing effect of DTH by se-pat was almost completely masked when it coexisted with Se1-pat(t) under the short-day conditions. Notably, the response of Ac-ef1 to day length was found to delay heading under the short-day conditions.


Assuntos
Regulação da Expressão Gênica de Plantas/efeitos da radiação , Genes de Plantas , Oryza/fisiologia , Oryza/efeitos da radiação , Fotoperíodo , Desenvolvimento Vegetal/genética , Meio Ambiente , Especificidade de Órgãos/genética , Oryza/crescimento & desenvolvimento , Estações do Ano
18.
Int J Mol Sci ; 19(12)2018 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-30544581

RESUMO

Rice nucleolin (OsNUC1), consisting of two isoforms, OsNUC1-L and OsNUC1-S, is a multifunctional protein involved in salt-stress tolerance. Here, OsNUC1-S's function was investigated using transgenic rice lines overexpressing OsNUC1-S. Under non-stress conditions, the transgenic lines showed a lower yield, but higher net photosynthesis rates, stomatal conductance, and transpiration rates than wild type only in the second leaves, while in the flag leaves, these parameters were similar among the lines. However, under salt-stress conditions at the booting stage, the higher yields in transgenic lines were detected. Moreover, the gas exchange parameters of the transgenic lines were higher in both flag and second leaves, suggesting a role for OsNUC1-S overexpression in photosynthesis adaptation under salt-stress conditions. Moreover, the overexpression lines could maintain light-saturation points under salt-stress conditions, while a decrease in the light-saturation point owing to salt stress was found in wild type. Based on a transcriptome comparison between wild type and a transgenic line, after 3 and 9 days of salt stress, the significantly differentially expressed genes were enriched in the metabolic process of nucleic acid and macromolecule, photosynthesis, water transport, and cellular homeostasis processes, leading to the better performance of photosynthetic processes under salt-stress conditions at the booting stage.


Assuntos
Oryza/efeitos dos fármacos , Oryza/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Oryza/efeitos da radiação , Fotossíntese/efeitos dos fármacos , Fotossíntese/efeitos da radiação , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/genética , Folhas de Planta/efeitos da radiação , Plantas Geneticamente Modificadas/efeitos dos fármacos , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/efeitos da radiação , Estresse Salino , Tolerância ao Sal
19.
Sci Rep ; 8(1): 14512, 2018 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-30267019

RESUMO

Although straw decomposition is important for ecosystem fertility and carbon balance, influence of ultraviolet-B (UV-B) radiation and nitrogen (N) deposition on this process is unclear. In this study, UV-B-exposed rice straw was decomposed under different N addition treatments for 15 months to investigate the indirect effects of UV-B radiation on straw chemistry and direct effects of N deposition on decomposition. UV-B exposure during rice plant growth changed the rice straw chemical composition, increasing the concentrations of acid-insoluble fraction (AIF), acid-soluble fraction, and UV-B-absorbing compounds. High N content had a negative effect on decomposition of rice straw exposed to enhanced and ambient UV-B radiation. Both AIF concentration and FTIR peak intensities indicated that lignin in rice straw was selectively preserved following N addition and UV-B radiation, reducing straw decomposition rate, which corresponded to lower activities of lignin-degrading enzymes in the later stage of decomposition. Thus, enhanced UV-B radiation during rice plant growth produced more recalcitrant substrates (lignin) and N reacted with lignin to produce more resistant compounds, further decreasing straw decomposition rate. UV-B radiation during plant growth and N deposition inhibit litter decomposition in agroecosystem, and their effects should be considered when establishing biogeochemical models in response to global changes.


Assuntos
Biodegradação Ambiental/efeitos da radiação , Nitrogênio/análise , Oryza/efeitos da radiação , Solo/química , Raios Ultravioleta , Carboidratos/análise , Carbono/análise , Concentração de Íons de Hidrogênio , Lignina/metabolismo , Lipídeos/análise , Monofenol Mono-Oxigenase/metabolismo , Nitrogênio/farmacologia , Ciclo do Nitrogênio , Oryza/metabolismo , Peroxidases/metabolismo , Proteínas de Plantas/análise , Caules de Planta/química , Caules de Planta/enzimologia , Caules de Planta/crescimento & desenvolvimento , Caules de Planta/efeitos da radiação , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier
20.
J Zhejiang Univ Sci B ; 19(8): 620-629, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30070085

RESUMO

Targeting Induced Local Lesions IN Genomes (TILLING) is a reverse genetics strategy for the high-throughput screening of induced mutations. γ radiation, which often induces both insertion/deletion (Indel) and point mutations, has been widely used in mutation induction and crop breeding. The present study aimed to develop a simple, high-throughput TILLING system for screening γ ray-induced mutations using high-resolution melting (HRM) analysis. Pooled rice (Oryza sativa) samples mixed at a 1:7 ratio of Indel mutant to wild-type DNA could be distinguished from the wild-type controls by HRM analysis. Thus, an HRM-TILLING system that analyzes pooled samples of four M2 plants is recommended for screening γ ray-induced mutants in rice. For demonstration, a γ ray-mutagenized M2 rice population (n=4560) was screened for mutations in two genes, OsLCT1 and SPDT, using this HRM-TILLING system. Mutations including one single nucleotide substitution (G→A) and one single nucleotide insertion (A) were identified in OsLCT1, and one trinucleotide (TTC) deletion was identified in SPDT. These mutants can be used in rice breeding and genetic studies, and the findings are of importance for the application of γ ray mutagenesis to the breeding of rice and other seed crops.


Assuntos
Mutação INDEL , Mutagênese , Oryza/genética , Produtos Agrícolas/genética , Produtos Agrícolas/efeitos da radiação , Raios gama , Técnicas Genéticas , Genoma de Planta , Homozigoto , Oryza/efeitos da radiação , Melhoramento Vegetal , Reação em Cadeia da Polimerase , Sementes , Análise de Sequência de DNA , Deleção de Sequência
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA