Oryza sativa

摘要： NRL3 is essential for the growth and development of rice leaves.In this study,we found that the loss function of NRL3 also delayed heading date under natural long daylight and short daylight conditions.The yeast two-hybrid and the bimolecular fluorescence complementation proved that NRL3interacts with OsK4,a Snf1-related kinase.OsK4 localized to the nucleus and expressed in various rice tissues.The rhythmic expression pattern of Os K4 was similar to NRL3 under long daylight and short daylight conditions.Knock-out mutants of Os K4 exhibited early heading under long daylight conditions,indicating that it acts as a negative regulator of heading date in rice.Interestingly,the OsK4 mutant under the nrl3 mutant background rescued the late heading phenotype of nrl3 under long daylight conditions,suggesting that Os K4 functions downstream of NRL3.Moreover,both NRL3 and Os K4 controlled heading date through regulating the expression of Hd3a and RFT1 genes.These findings shed light on the heading date regulation in rice and provide a sound theoretical base to improve regional adaptability of rice.

摘要： Sugar transportation and sugar-to-starch metabolism are considered important processes in seed development and embryo viability.A few plant SWEET proteins acting as sugar transporters have been reported to function in inflorescence and/or seed development.Here,we identified seven members of the 21 Os SWEET genes in rice that play essential roles in sugar transportation and sugar-to-starch conversion in seed development.Nineteen Os SWEET genes exhibiting different expression patterns during inflorescence and seed development were knocked out individually by CRISPR/Cas9.One third of the mutants showed decreased fertile pollen viability and shriveled mature caryopses,resulting in weakened seed traits.Grain fill-related genes but not representative grain shape-regulating genes showed attenuated expression in the mutants.Seed of each of these mutants accumulated more sucrose,glucose or fructose but less starch.Among all Os SWEET genes,Os SWEET4 and Os SWEET11 had major effects on caryopsis development.The sugar-to-starch metabolic pathway was significantly altered in ossweet11 mutants based on differential expression analysis in RNA sequencing assays,confirming that Os SWEET11 functions as a sugar transporter with a key role in seed development.These results help to decipher the multiple functions of Os SWEET genes and to show how they might be used in genetic improvement of rice.

摘要： The Asian cultivated rice Oryza sativa can be classified into two major subspecies:japonica/geng and indica/xian.There are large physiological and phenotypic differences between the two subspecies,with each having its advantages and disadvantages.Understanding the differences between xian and geng could provide a foundation for cultivar improvement based on hybridization between subspecies in order to synthesize favorable traits.We review the origin and domestication of xian and geng rice,compare their differences in terms of physiological and phenotypical traits,and describe the molecular mechanism differences between the subspecies.Based on this knowledge,we propose an ideal plant architecture of geng rice varieties for northern regions.

摘要： Wheat straw burial has great potential to sustain rice production under alternate wetting and drying(AWD)irrigation.A field experiment was conducted with three wheat straw burial treatments,including without straw burial(NSB),with light straw burial of 300 kg/hm^(2)(LSB)and dense straw burial of 800 kg/hm^(2)(DSB),as well as three AWD regimes:alternate wetting/moderate drying(AWMD),alternate wetting/severe drying(AWSD)and alternate wetting/critical drying(AWCD).The rice growth and grain quality were higher in LSB and NSB than those in NSB under the same AWD regime.The AWMD×DSB treatment resulted in the highest yield,brown rice rate,milled rice rate,amylose content and protein content.Conversely,the AWCD×NSB treatment led to the lowest yield,brown rice rate,milled rice rate,amylose content and protein content.The active absorption area and nitrate reductase activity of roots were higher in the AWMD×DSB treatment than those in the AWCD×NSB treatment,as the former increased organic carbon and nitrogen contents in the rhizosphere,whereas the latter reduced their availability.Total soluble protein content and glutamine synthetase activity were greater in the AWMD×DSB treatment than those in the AWCD×NSB treatment.The activities of superoxide dismutase and catalase were higher in the AWMD×DSB treatment compared with the AWCD×NSB treatment,leading to the amelioration of oxidative cell injury,as shown by a lower malonaldehyde level.This study suggested that farmers should implement AWMD irrigation after leaving the straw residues in the field,followed by deep tillage to improve soil quality and mitigate the drought stress cycles of AWD.This approach can improve rice growth and grain quality and alleviate the problems of disposal of straw residues and water scarcity for sustainable rice production.

摘要： Species of wild rice(Oryza spp.)possess a wide range of stress tolerance traits that can be potentially utilized in breeding climate-resilient cultivated rice cultivars(Oryza sativa)thereby aiding global food security.In this study,we conducted a greenhouse trial to evaluate the salinity tolerance of six wild rice species,one cultivated rice cultivar(IR64)and one landrace(Pokkali)using a range of electrophysiological,imaging,and whole-plant physiological techniques.Three wild species(O.latifolia,O.officinalis and O.coarctata)were found to possess superior salinity stress tolerance.The underlying mechanisms,however,were strikingly different.Na^(+)accumulation in leaves of O.latifolia,O.officinalis and O.coarctata were significantly higher than the tolerant landrace,Pokkali.Na^(+)accumulation in mesophyll cells was only observed in O.coarctata,suggesting that O.officinalis and O.latifolia avoid Na^(+)accumulation in mesophyll by allocating Na^(+)to other parts of the leaf.The finding also suggests that O.coarctata might be able to employ Na^(+)as osmolyte without affecting its growth.Further study of Na^(+)allocation in leaves will be helpful to understand the mechanisms of Na^(+)accumulation in these species.In addition,O.coarctata showed Proto Kranz-like leaf anatomy(enlarged bundle sheath cells and lower numbers of mesophyll cells),and higher expression of C4-related genes(e.g.,NADPME,PPDK)and was a clear outlier with respect to salinity tolerance among the studied wild and cultivated Oryza species.The unique phylogenetic relationship of O.coarctata with C4 grasses suggests the potential of this species for breeding rice with high photosynthetic rate under salinity stress in the future.

摘要： Heading date(or flowering time),an important agronomic trait in crop species,is closely associated with regional adaptation and yield.Members of the Pseudo-Response Regulator(PRR)family play key roles in regulating flowering.However,their role and molecular mechanism controlling heading date in rice is not very clear.Here,we identified rice OsPRR protein,OsPRR59,which delayed heading under longday conditions.OsPRR59 positively regulates yield by affecting plant height,secondary branches number per panicle,grain number per panicle,seed setting rate,and grain weight per plant.OsPRR59 is expressed in most tissues and its protein is localized to the nucleus.We also found that OsPRR59 directly binds to the promoter of Ehd3 to inhibit its expression.Compared with the WT,osprr59 ehd3 showed a significantly delayed heading phenotype,as did the ehd3 mutant.This was opposite to the phenotype of the osprr59 mutant,confirming that Ehd3 acted downstream of OsPRR59 in regulating rice flowering.Our results identified a direct regulator of Ehd3,and revealed a novel molecular mechanism of clock component OsPRR proteins in regulating heading date and provide a new genetic resource for fine-tuning heading date in rice.

摘要： This study reports the effects of Oryza sativa AUXIN BINDING PROTEIN57(OsABP57)overexpression towards flooding in rice.OsABP57 was previously reported to activate plasma membrane H+-ATPase.Earlier studies address the ability of transgenic OsABP57 overexpression in enduring drought and salinity stresses but none on the flooding.In this study,complete submergence analysis was carried out and several morphophysiological parameters were analyzed such as plant height,root architecture and relative chlorophyll content.Results showed that there are no differences between OsABP57 overexpression rice compared to MR219 control rice in terms of chlorophyll content and plant height after 1-3 weeks of flooding treatments.Root analysis,however,found that transgenic rice OsABP57 produced more adventitious roots compared to MR219 rice under normal condition,which may be due to the role of the gene that encodes for auxin binding protein.The semi-quantitative polymerase chain reaction(PCR)on Oryza sativa pyruvate decarboxylase(OsPDC)gene after two weeks of flooding treatment showed an increase of expression in OsABP57 transgenic compared to MR219.Overall,the overexpression of OsABP57 did not show any significant difference in terms of morphophysiological analysis between the transgenic line and MR219,yet,there is an increase of OsPDC gene in the transgenic background which may need further experimental analysis in the future to map the network between auxin and hypoxia core genes.

摘要： Although natural variations in rice flavonoids exist, and biochemical characterization of a few flavonoid glycosyltransferases has been reported, few studies focused on natural variations in tricin-lignan-glycosides and their underlying genetic basis. In this study, we carried out metabolic profiling of tricin-lignan-glycosides and identified a major quantitative gene annotated as a UDPdependent glycosyltransferase OsUGT706C2 by metabolite-based genome-wide association analysis. The putative flavonoid glycosyltransferase OsUGT706C2 was characterized as a flavonoid 7-O-glycosyltransferas in vitro and in vivo. Although the in vitro enzyme activity of OsUGT706C2 was similar to that of OsUGT706D1, the expression pattern and induced expression profile of OsUGT706C2 were very different from those of OsUGT706D1. Besides, OsUGT706C2 was specifically induced by UV-B. Constitutive expression of OsUGT706C2 in rice may modulate phenylpropanoid metabolism at both the transcript and metabolite levels. Furthermore, overexpressing OsUGT706C2 can enhance UV-B tolerance by promoting ROS scavenging in rice. Our findings might make it possible to use the glycosyltransferase OsUGT706C2 for crop improvement with respect to UVB adaptation and/or flavonoid accumulation, which may contribute to stable yield.

摘要： To assist in upland rice breeding programs, estimated genetic and phenotypic parameters are extremely important in the selection of superior lines. Thus, the objective of this study was estimate the genetic and phenotypic parameters of upland rice lines of the breeding program of UFLA in partnership with Embrapa Arroz e Feijao and Epamig. The experiment was installed in an experimental area of the Department of Agriculture at UFLA. It was evaluated 36 upland rice lines of the preliminary trial of the 2014/15 season, in randomized blocks, with three replications and plots consisted of five rows and each row has four meters. For this, it was evaluated the characters: plant height (cm), yield (kg·ha-1), 100-grain weight, days until flowering, percentage of filled grains and rice blast severity. The variance analysis and genetic parameters were estimated using the software SAS. To evaluate the experimental precision was estimated the accuracy, which varied between 63% and 98%, showing experimental precision, moderate to high. The lines differed significantly for all characters, meaning there is genetic variability among genotypes evaluated. With intensity of selection of 10% of lines, it was obtained a genetic gain of 325.29 kg·ha-1 in the character productivity, a plant height (cm) reduction in 5.50 cm, and days until flowering, with a reduction of 9.23 days, with selection of earlier plants. The estimated values for heritability ranged from 38% - 96%. Estimates confirm the possible success with the selection of the upland rice lines for these characters.

摘要： The present work aimed to evaluate the effect of different water stress levels on the development of both rice and barnyardgrass. The study was established into greenhouse, in completely randomized design, in factorial scheme 2 × 5, with four replications. Factor “A” comprised the plant species (rice cv. BRS Querência, or the weed Echinochloa crusgalli), and factor “B” comprised the water stress levels: (T1) continuous flood (CF);(T2) 0 kPa (saturated soil);(T3) 10 kPa;(T4) 40 kPa;and (T5) 100 kPa. Plant emergence was assessed every day;plant length was measured 30 days after planting. At the end of the experiment, the number of leaves per plant, root length and shoot and root dry mass were determined. Our data supply evidence that under moderate water stress, up to approximately 40 kPa, rice tends to perform better than barnyardgrass in the initial stage of crop growth, when under equivalent plant density. However, barnyardgrass is usually present in much higher plant density than crop plants in fields traditionally cropped with rice. Thus, efficient control of barnyardgrass should be accomplished to avoid damage to rice crop by competition for environmental resources.