Search Results (230)

Sorghum is an important cereal crop. The maintenance of leaf color significantly influences sorghum growth and development. Although the mechanisms of leaf color mutation have been well studied in many plants, those in sorghum remain largely unclear. Here, we identified a sorghum gradient-pale-green leaf mutant (sbgpgl1) from the ethyl methanesulfonate (EMS) mutagenesis mutant library. Phenotypic, photosynthesis-related parameter, ion content, transcriptome, and metabolome analyses were performed on wild-type BTx623 and the sbgpgl1 mutant at the heading stage, revealing changes in several agronomic traits and physiological indicators. Compared with BTx623, sbgpgl1 showed less height, with a smaller length and width of leaf and panicle. The overall Chl a and Chl b contents in sbgpgl1 were lower than those in BTx623. The net photosynthetic rate, stomatal conductance, and transpiration rate were significantly reduced in sbgpgl1 compared to BTx623. The content of copper (Cu), zinc (Zn), and manganese (Mn) was considerably lower in sbgpgl1 leaves than in BTx623. A total of 4469 differentially expressed genes (DEGs) and 775 differentially accumulated metabolites (DAMs) were identified by RNA-seq and UPLC-MS/MS. The results showed that sbgpgl1 primarily influenced sorghum metabolism by regulating metabolic pathways and the biosynthesis of secondary metabolites, especially flavonoids and phenolic acids, resulting in the gradient-pale-green leaf phenotype. These findings reveal key genes and metabolites involved on a molecular basis in physiological variations of the sorghum leaf color mutant. Full article

Ozone pollution decreases rice yield and quality in general, but how ozone stress changes grain-filling capacity is unclear. A chamber experiment was conducted to compare the effects of ozone exposure during the rice growth season on the grain-filling capacity and quality of spikelets located on the upper primary rachis (superior spikelets, SS) and the lower secondary rachis (inferior spikelets, IS). Ozone stress significantly decreased filled grain percentage by 41.4% and grain mass by 10.2% in IS, but had little effect on grain-filling capacity in SS. Consistent with the reduction in grain mass, ozone stress decreased grain volume, mainly due to reduced grain thickness, and IS was reduced more than SS. After removing the hull, brown rice obtained from ozone treatment exhibited higher proportions of immature and abnormal kernels, resulting in a substantially lower proportion of perfect kernels. Under ozone stress, the proportion of perfect kernels was only one-third in IS, compared with two-thirds in SS. Ozone stress affected the pasting properties of brown rice for both SS and IS, as shown by the decreased amylose content, and the increased maximum viscosity, minimum viscosity, final viscosity, setback, and peak time of the rapid visco analyzer profile. Out of fourteen traits related to nutritional quality of brown rice, only five showed significant increases under ozone stress, and they were the concentrations of albumin, prolamin, sulfur, copper, and manganese. The differential ozone responses between SS and IS were rather small for rice pasting properties and chemical compositions as shown by very few significant interactions between ozone and grain position. It is concluded that ozone stress during plant growth imposed more adverse effects on IS than SS in terms of grain-filling capacity and appearance quality, suggesting an enlarged asynchronous grain-filling pattern in rice panicles under ozone pollution. Strategies to improve the grain-filling capacity of IS are needed to mitigate ozone-induced damage to rice production. Full article

The architecture of rice tillers plays a pivotal role in yield potential, yet conventional phenotyping methods have struggled to capture these intricate three-dimensional (3D) structures with high fidelity. In this study, a 3D model reconstruction method was developed specifically for rice tillers to overcome the challenges posed by their slender, feature-poor morphology in multi-view stereo-based 3D reconstruction. By applying strategically designed colorful reference markers, high-resolution 3D tiller models of 231 rice landraces were reconstructed. Accurate phenotyping was achieved by introducing ScaleCalculator, a software tool that integrated depth images from a depth camera to calibrate the physical sizes of the 3D models. The high efficiency of the 3D model-based phenotyping pipeline was demonstrated by extracting the following seven key agronomic traits: flag leaf length, panicle length, first internode length below the panicle, stem length, flag leaf angle, second leaf angle from the panicle, and third leaf angle. Genome-wide association studies (GWAS) performed with these 3D traits identified numerous candidate genes, nine of which had been previously confirmed in the literature. This work provides a 3D phenomics solution tailored for slender organs and offers novel insights into the genetic regulation of complex morphological traits in rice. Full article

The utilization of saline–alkali land for rice cultivation is critical for global food security. However, most existing studies on rice salt tolerance focus on the seedling stage, with limited insights into tolerance mechanisms during reproductive growth, particularly at the panicle initiation stage (PI). Leveraging precision salinity-control facilities, this study imposed four salt stress gradients (0, 3, 5, and 7‰) to dissect the differential response mechanisms of six rice varieties (YXYZ: Yuxiangyouzhan, JLY3261: Jingliangyou3261, SLY91: Shuangliangyou91, SLY138: Shuangliangyou138, HLYYHSM: Hualiangyouyuehesimiao, and SLY11:Shuangliangyou111) during PI. The results revealed that increasing salinity significantly reduced tiller number (13.14–68.04%), leaf area index (18.58–57.99%), canopy light interception rate (11.91–44.08%), and net photosynthetic rate (2.63–52.42%) (p < 0.001), accompanied by reactive oxygen species (ROS)-induced membrane lipid peroxidation. Integrative analysis of field phenotypic and physiological indices revealed distinct adaptation strategies: JLY3261 rapidly activated antioxidant enzymes under 3‰ salinity, alleviating lipid peroxidation (no significant difference in H₂O₂ or malondialdehyde content compared to 0‰ salinity) and maintaining tillering and aboveground biomass. SLY91 tolerated 7‰ salinity via CAT/POD-mediated lipid peroxide degradation, with H₂O₂ and malondialdehyde contents increasing initially but decreasing with escalating stress. These findings highlight genotype-specific antioxidant strategies underlying salt-tolerance mechanisms and the critical need for integrating phenomics–physiological assessments at reproductive stages into salt-tolerance breeding pipelines. Full article

This study evaluated the effects of one-time application of controlled-release fertilizer (CRF) on rice (Oryza sativa L.) grain yield, grain quality, and agronomic nitrogen use efficiency (ANUE, ANUE (kg/kg) = (Grain yield with N application − grain yield without N application)/N application amount) in coastal saline soils. A two-year field experiment (2023–2024) was conducted using two rice varieties (Nanjing 5718 and Yongyou 4953) under four nitrogen treatments: N0 (no nitrogen fertilization), N1 (270 kg·hm⁻², with a ratio of 5:1:2:2 at 1-day before transplanting, 7-day after transplanting, panicle initiation, and penultimate-leaf appearance stage, respectively), N2 (270 kg·hm⁻², one-time application at 1-day before transplanting as 50% CRF with 80-day release period + 50% urea), and N3 (270 kg·hm⁻², 50% one-time application of CRF with 120-day release period at the seedling stage + 50% urea at 1-day before transplanting). Compared with N1, the N3 treatment significantly increased grain yield by 10.2% to 12.9% and improved ANUE by 18.5% to 51.6%. It also improved processing quality (higher brown rice, milled rice, and head rice rates), appearance quality (reduced chalkiness degree and chalky rice percentage), and taste value (by 19.3% to 31.2%). These improvements were associated with lower amylose, protein, and soluble sugar contents and favorable changes in starch composition and pasting properties. While N2 slightly improved some quality traits, it significantly reduced yield and ANUE. Correlation analysis revealed that starch and protein composition, as well as pasting properties, were significantly associated with taste value and related attributes such as appearance, stickiness, balance degree, and hardness. Overall, one-time application of CRF with a 120-day release period at the seedling stage, combined with basal urea, offers an effective strategy to boost yield, quality, and ANUE in coastal saline rice systems. Full article

Rice is a staple food for over half of the world’s population, and it is grown in over 100 countries. Rice blast disease can cause 10% to 30% crop loss, enough to feed 60 million people. Breeding for resistance can help farmers avoid costly fungicides. This study assessed the relationship between rice blast disease and zinc or anthocyanin content in biofortified rice. Susceptibility to foliar and panicle blast was assessed in a rice panel which differed on grain zinc content and pigmentation. A rice panel (n = 23) was challenged with inoculum of two isolates of Magnaporthe oryzae in a screenhouse-based assay. The zinc content with foliar blast severity was analyzed in the leaves and grain of a subset of non-inoculated rice plants. The effect of foliar zinc supplementation on seedlings was assessed by varying levels of zinc fertilizer solution on four blast susceptible cultivars at 14 days after planting (DAP), followed by inoculation with the blast pathogen at 21 DAP. Foliar blast severity was scored on a 0–9 scale at 7 days after inoculation. The rice panel was scored for anthocyanin content, and the data were correlated with foliar blast severity. The panel was grown in the field, and panicle blast, grain yield and yield-related agronomic traits were measured. Significant differences were observed in foliar blast severity among the rice genotypes, with IRBLK-KA and IR96248-16-2-3-3-B having mean scores greater than 4, as well as BASMATI 370 (a popular aromatic variety), while the rest of the genotypes were resistant. Supplementation with foliar zinc led to a significant decrease in susceptibility. A positive correlation was observed between foliar and panicle blast. The Zn in the leaves was negatively correlated with foliar blast severity, and had a marginally positive correlation with panicle blast. There was no relationship between foliar blast severity and anthocyanin content. Grain yield had a negative correlation with panicle blast, but no correlation was observed between Zn in the grain and grain yield. This study shows that Zn biofortification in the grain may not enhance resistance to foliar and panicle blast. Furthermore, the zinc-biofortified genotypes were not agronomically superior to the contemporary rice varieties. There is a need to apply genomic selection to combine promising alleles into adapted rice genetic backgrounds. Full article

Morkhor 60-3 is an upland rice variety primarily cultivated in northeastern Thailand. This glutinous rice is valued for its adaptability and rich aroma but remains susceptible to significant diseases, particularly blast and bacterial blight. Using resistant varieties represents the most cost-effective approach to address this limitation. This study incorporated the QTLs/genetic markers qBl1, qBl2, and xa5 from Morkhor 60-1 through marker-assisted backcrossing. From the BC₁F₃ population, ten lines were selected based on their parentage and evaluated for blast resistance using a spray inoculation method with 12 isolates of Pyricularia oryzae, and for bacterial blight (BB) resistance using a leaf-clipping method with nine isolates of Xanthomonas oryzae pv. oryzae. Broad-spectrum resistance (BSR) was also assessed in the lines for both diseases. Subsequently, BC₁F₄ lines were evaluated for field performance, including agronomic traits and aroma. Results identified three superior lines, BC₁F₄ 22-7-140-4, BC₁F₄ 22-7-322-5, and BC₁F₄ 22-7-311-9, that demonstrated resistance to both BB and blast pathogens with average BSR values of 0.61 and 1.00, 0.66 and 1.00, and 0.55 and 0.87, respectively. These lines also exhibited enhanced performance in flowering date, plant height, panicle number per plant, grain number per plant, and grain weight. These findings demonstrate the effectiveness of marker-assisted selection (MAS) for gene pyramiding in rice improvement. Full article

In China, agriculture is currently highly dependent on chemical nitrogen. This leads to low nitrogen use efficiency and high nitrogen losses. Considering the issues caused by excessive chemical fertilizer, integrated nutrient management using organic and chemical fertilizer sources is important. To clarify how partial substitution of chemical fertilizer by organic fertilizer affects rice yield, physiological traits, and nitrogen use efficiency, we conducted a two-year field trial in 2021 and 2022, and used two rice cultivars, Shendao47 (SD47) and Shendao505 (SD505), which were grown in the field with five fertilization treatments: (1) CK (zero N application); (2) CF (100% chemical fertilizer); (3) OR10 (10% organic fertilizer + 90% chemical fertilizer); (4) OR20 (20% organic fertilizer + 80% chemical fertilizer); and (5) OR30 (30% organic fertilizer + 70% chemical fertilizer). The results show that the partial organic substitution (OR) treatments improved the yield by 1–10% for two cultivars by increasing effective panicles and grain filling. The increase in grain filling was related to the photosynthetic parameters, including LAI, chlorophyll content, and net photosynthetic rate during the grain-filling stage. The photosynthetic parameters of OR treatments were higher than those of CF treatment. Additionally, with the increase in organic fertilizer application rates, the grain yield, agronomic N use efficiency, partial factor productivity of applied N, and physiological N use efficiency increased at first and then decreased, peaking in OR20 treatment. Conclusively, the 20% organic fertilizer with 80% chemical fertilizer is a promising option for higher yield and improved N utilization for both cultivars. This study provides a sustainable nutrient management strategy to improve crop yield with high nutrient use efficiency. Full article

Nitrogen is a crucial element that impacts rice yield and its constituent factors. The effects of reduced nitrogen levels on yield constitute is a complex quantitative trait that is controlled by multiple genes, and its genetic basis requires further exploration. In this study, 562 MAGIC line population and 284 germplasm varieties were used for genome-wide association analysis (GWAS) and haplotype analysis, aiming to detect quantitative trait loci (QTL) and candidate genes associated with tolerance to low nitrogen levels. The ratio of effective panicle number per plant (REPN), total number of grains per panicle (RTGN), seed setting rate (RSSR), thousand grain weight (RTGW), biomass (RBM), harvest index (RHI), and grain yield per plant (RGY) of low to normal nitrogen conditions were measured in this study. The RBM and RHI were directly closely related to RGY, while the RSSR indirectly and positively affected RGY through RHI, and the REPN and RTGN mainly indirectly and positively affected RGY through RBM. LOC_Os06g06440 was the most likely gene affecting low-nitrogen-tolerance-related traits in rice within the region, ranging from 2.898 Mb to 3.046 Mb (148 kb) on chromosome 6, and the haplotype AA, with a significantly larger mean RGY of 0.95 and 1.53 in the MAGIC and germplasm varieties, respectively, was the advanced allele of LOC_Os06g06440. Nine xian (indica) varieties (IRIS_313-11624, IRIS_313-10932, CX382, B067, B249, IRIS_313-8215, IRIS_313-10544, B052, and B233) carrying the superior haplotype (AA) of LOC_Os06g06440 and having a higher RGY were selected for the molecular marker-assisted selection of low nitrogen tolerance in rice. These results will enhance our knowledge of the genetic basis of tolerance to low levels of nitrogen and provide valuable information for improving tolerance to low levels of nitrogen in rice-breeding programs. Full article

The Yangtze River Delta (YRD) is one of the most important japonica rice planting areas in China. Balancing the resistance, yield, and quality has always been a core issue in rice breeding due to the negative correlation among these three factors, while the broad-spectrum blast resistance gene Piz is closely linked with Hd1, the major gene regulating days to heading (DTH), and a precise combination of their beneficial alleles plays a key role in synchronously improving blast resistance and the regional adaptability of japonica rice in YRD. In this study, using the backcross progeny population derived from backbone parent ZD9471 and W1063, two alleles of Hd1 were identified. Then, through molecular marker-assisted selection combined with Green Super Rice 40K (GSR40K) chip-based screening, six introgression lines (ILs) with two different alleles combinations of Hd1 and Pigm were obtained. An evaluation of the blast resistance, yield, and quality traits showed that compared with the recipient parent, the panicle blast resistance of ILs was significantly enhanced; the grain number per panicle increased consistently with the delaying of the growth period, leading to higher yield in the ILs; the grain quality were synchronously improved. Two representative lines with similar genetic backgrounds but a significantly different regional adaptability, exhibiting a good blast resistance, high yield, and prominent quality were approved and demonstrated promising application prospects. Full article

Bacterial leaf streak (BLS) is one of the internationally significant quarantine diseases in rice. Effectively utilizing BLS resistance genes from wild rice (Oryza rufipogon Griff.) to breed new varieties offers a fundamental solution for BLS control. This study focused on the fine mapping of the BLS resistance gene bls2 and the development of closely linked molecular markers for breeding BLS-resistant lines. Using a Guangxi common wild rice accession DY19 (carrying bls2) as the donor parent and the highly BLS-susceptible indica rice variety 9311 as the recipient parent, BLS-resistant rice lines were developed through multiple generations of backcrossing and selfing, incorporating molecular marker-assisted selection (MAS), single nucleotide polymorphism(SNP) chip genotyping, pathogen inoculation assays, and agronomic trait evaluation. The results showed that bls2 was delimited to a 113 kb interval between the molecular markers ID2 and ID5 on chromosome 2, with both markers exhibiting over 98% accuracy in detecting bls2. Four stable new lines carrying the bls2 segment were obtained in the BC₅F₄ generation. These four lines showed highly significant differences in BLS resistance compared with 9311, demonstrating moderate resistance or higher with average lesion lengths ranging from 0.69 to 1.26 cm. Importantly, no significant differences were observed between these resistant lines and 9311 in key agronomic traits, including plant height, number of effective panicles, panicle length, seed setting rate, grain length, grain width, length-to-width ratio, and 1000-grain weight. Collectively, two molecular markers closely linked to bls2 were developed, which can be effectively applied in MAS, and four new lines with significantly enhanced resistance to BLS and excellent agronomic traits were obtained. These findings provide technical support and core germplasm resources for BLS resistance breeding. Full article

Integrated aquaculture–agriculture systems (IAASs) offer a sustainable approach to mitigating soil salinity by utilizing aquaculture effluents for irrigation. This study evaluates the growth performance of Nile tilapia (Oreochromis niloticus) and red tilapia (Oreochromis spp.) under varying salinity conditions and investigates their effluents on intercropped wheat and sugar beet. A field experiment was conducted using a randomized block design with seven treatments: control (chemical fertilizers dissolved in freshwater) and brackish water effluents from Nile tilapia and red tilapia at salinities of 5 ppt and 10 ppt as monocultures or mixed polycultures. Fish growth parameters were assessed, while wheat and sugar beet morphological and yield traits were monitored. Statistical analyses, including correlation and principal component analysis, were performed. Red tilapia outperformed Nile tilapia at 10 ppt salinity, achieving the highest final weight (174.52 ± 0.01 g/fish) and weight gain (165.78 ± 0.01 g/fish), while the mixed polyculture at 10 ppt exhibited optimal feed conversion (FCR: 1.32 ± 0.01). Wheat growth and yield traits (plant height, stalk diameter, and panicle weight) declined significantly under salinity stress, with 10 ppt treatments reducing plant height by ~57% compared to the control. Conversely, sugar beet demonstrated resilience, with total soluble solids (TSS) increasing by 20–30% under salinity. The mixed effluent partially mitigated salinity effects on wheat at 5 ppt but not at 10 ppt. This study highlights the potential of IAAS in saline environments, demonstrating red tilapia’s adaptability and sugar beet’s resilience to salinity stress. In contrast, wheat suffered significant reductions in growth and yield. Full article

The way in which alternate wetting and drying irrigation (AWD), as a water-saving practice promoted in rice (Oryza sativa L.) production systems, could enhance the productivity and water use efficiency (WUE) attracts broad attention. This study selected six mid-season indica rice varieties to investigate the impacts of AWD and conventional irrigation (CI) on grain yield, WUE, grain filling, and root traits. A two-year field experiment demonstrated that grain yields and WUE were significantly increased with varietal improvements. With the improvement of varieties, the maximum grain filling rate and mean grain filling rate for both apical superior and basal inferior spikelets were progressively enhanced during the grain filling stage. Compared to CI, AWD significantly enhanced grain yield and WUE. Flag leaf photosynthetic rate and root characteristics, including root weight, root length, root absorbing surface area, root oxidation activity, and zeatin (Z) + zeatin riboside (ZR) contents in panicles, roots, and root bleeding, were superior under AWD across early, mid, and late grain filling stages. Correlation and path analysis showed that improved grain filling in basal inferior spikelets was attributed to delayed root senescence during the grain filling stage under AWD. These results indicated that AWD would be a better irrigation regime to improve yield and WUE by optimizing grain filling and root growth for modern varieties. Full article

Auxin plays a versatile role in regulating plant growth and development. The auxin efflux carrier PIN-FORMED (PIN) proteins dictate the distribution and maximum of auxin within various tissues. Despite extensive research on OsPINs in recent years, their functions in abiotic stress resistance, particularly cold tolerance, remain poorly understood. Here, we investigated the role of OsPIN5b in rice (Oryza sativa L.) growth and development, as well as its contribution to cold tolerance using overexpression technology. Overexpression of OsPIN5b (OE) resulted in reduced shoot height and a lower number of adventitious roots at the seedling stage. Transgenic rice plants exhibited an earlier heading date, stunted growth, and compromised agronomic traits, including shortened panicle length, decreased grain number per panicle, reduced seed size, and lower seed setting rate during the reproductive stage. Auxin content in the transgenic lines was significantly elevated, as indicated by the upregulation of the auxin-responsive gene OsIAA20 and increased auxin levels quantified using a newly developed method. Compared with wild-type plants, the cold tolerance of OE plants was markedly reduced, as evidenced by lower survival rates, higher levels of electrolyte leakage, and increased malondialdehyde (MDA) production following cold treatment. In line with this, the transgenic lines produced less soluble sugar and proline, while accumulating more hydrogen peroxide (H₂O₂) and superoxide anion radicals (${\mathrm{O}}_2^{-}$) after cold treatment. Furthermore, the activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), were notably decreased upon cold treatment compared with those in WT plants. Additionally, OsRBOHH, which plays a role in ROS production, was significantly upregulated in transgenic lines both before and after chilling stress, suggesting that OsRBOHH plays a potential role in regulating ROS production. Collectively, overexpression of OsPIN5b substantially disturbs auxin homeostasis, resulting in impaired plant architecture and agronomic traits. More importantly, the upregulation of OsPIN5b compromises rice cold tolerance by perturbing ROS homeostasis and adversely influencing the accumulation of soluble sugar and proline. Full article

Nanjing series japonica rice varieties developed by the Institute of Food Crops, Jiangsu Academy of Agricultural Sciences in China have the characteristics of an excellent taste quality, high yield, and good resistance. They are widely promoted and applied in the lower reaches of the Yangtze River in China’s japonica rice planting areas. In response to the problem of the lack of coordination between nitrogen fertilizer management measures and variety characteristics in production, which makes it difficult to synergistically improve yield and quality, this study adopted a split-plot experimental design to study the effect of nitrogen fertilizer application on yield and rice quality of Nanjing series japonica rice varieties. In 2021, four nitrogen application rates of 0 (N₁), 150 (N₂), 300 (N₃), and 450 (N₄) kg hm⁻² (all pure nitrogen) were set up, and in 2022, four treatments of 120 (N₁), 180 (N₂), 240 (N₃), and 300 (N₄) kg hm⁻² were set up, all with nitrogen application rate as the main plot factor and variety as the sub-plot factor. The results showed that the differences between the different nitrogen fertilizer treatments were significant at the 5% or 1% level, except for the milled rice rate, head rice rate, peak viscosity, setback viscosity, and paste temperature in 2021 and panicle number, grain number per panicle, all Rapid Visco-analyzer (RVA) characteristic values, and amylose content in 2022. With an increase in the nitrogen application rate, the number of panicles, grain number per panicle, and yield increased. Either the rates of brown rice, milled rice, or head rice and chalky grains or chalkiness showed an increase trend. The peak viscosity, hot viscosity, final viscosity, and breakdown viscosity decreased, while the setback viscosity increased. For the quality of cooked rice, the hardness increased, appearance, viscosity, and balance decreased, protein content increased, and taste value decreased. The interaction between nitrogen application rate and variety was significant at p < 0.05 or p < 0.01 only for yield components, processing quality, and rice protein content in 2021 and for eating and cooking quality, appearance quality, and peak viscosity in 2022. Other traits were not significant. The comprehensive results from two years of experiments showed that, under the conditions of this experiment, a nitrogen application rate of 240–300 kg hm⁻² could improve the quality of rice in the Nanjing series varieties while maintaining a high yield. The results of this experiment have a guiding significance for the high-yield and high-quality cultivation of excellent-tasting Nanjing series japonica rice. Full article