Background: Balancing the yield, quality and resistance to disease is a daunting challenge in crop breeding due to the negative relationship among these traits. Large-scale genomic landscape analysis of germplasm resources is considered to be an efficient approach to dissect the genetic basis of the complex traits. Central China is one of the main regions where thejaponicarice is produced. However, dozens of high-yield rice varieties in this region still exist with low quality or susceptibility to blast disease, severely limiting their application in rice production.Results: Here, we re-sequence 200japonicarice varieties grown in central China over the past 30 years and analyze the genetic structure of these cultivars using 2.4 million polymorphic SNP markers. Genome-wide association mapping and selection scans indicate that strong selection for high-yield and taste quality associated with low-amylose content may have led to the loss of resistance to the rice blast fungusMagnaporthe oryzae. By extensive bioinformatic analyses of yield components, resistance to rice blast, and taste quality, we identify several superior alleles for these traits in the population. Based on this information, we successfully introduce excellent taste quality and blast-resistant alleles into the background of two high-yield cultivars and develop two elite lines, XY99 and JXY1, with excellent taste, high yield, and broad-spectrum of blast resistance.Conclusions: This is the first large-scale genomic landscape analysis ofjaponicarice varieties grown in central China and we demonstrate a balancing of multiple agronomic traits by genomic-based strategy.

Cold stress is a major factor limiting rice (Oryza sativa L.) production worldwide, especially at the seedling and booting stages. Identification of genes associated with cold tolerance (CT) in rice is important for sustainable food production. Here, we report the results of a genome-wide association study (GWAS) to identify the genetic loci associated with CT by using a 1,033-accession diversity panel. We identified five CT-related genetic loci at the booting stage. Accessions carrying multiple cold-tolerant alleles displayed a higher seed setting rate than did accessions that had no cold-tolerant alleles or carried a single allele. At the seedling stage, eight genetic loci related to CT have been identified. Among these, LOC_Os10g34840 was identified as the candidate gene for the qPSR10 genetic locus that is associated with CT in rice seedlings. A single-nucleotide polymorphism (SNP), SNP2G, at position 343 in LOC_Os10g34840 is responsible for conferring cold tolerance at the seedling stage in rice. Further analysis of the haplotype network revealed that SNP2G was present in 80.08% of the temperate japonica accessions but only 3.8% of the indica ones. We used marker-assisted selection to construct a series of BC4F3 near-isogenic lines possessing the cold-tolerance allele SNP2G. When subjected to cold stress, plants carrying SNP2G survived better as seedlings and showed higher grain weight than plants with carrying the SNP2A allele. The CT-related loci identified here and the functional verification of LOC_Os10g34840 will provide genetic resources for breeding cold-tolerant varieties and for studying the molecular basis of cold tolerance in rice.

Reverse transcription quantitative real-time PCR (RT-qPCR) is arguably the most prevalent and accurate quantitative gene expression analysis. However, selection of reliable reference genes for RT-qPCR in rice (Oryza sativa) is still limited, especially for a specific tissue type or growth condition. In this study, we took the advantage of our RNA-seq datasets encompassing data from five rice varieties with diverse treatment conditions, identified 12 novel candidate reference genes, and conducted rigorous evaluations of their suitability across typical rice tissues. Comprehensive analysis of the leaves, shoots, and roots of two rice seedlings subjected to salt (30 mmol/L NaCl) and drought (air-dry) stresses have revealed that OsMED7, OsACT1, and OsOS-9 were the robust reference genes for leaf samples, while OsACT1, OsZOS3-23, and OsGDCP were recommended for shoots and OsMED7, OsOS-9, and OsGDCP were the most reliable reference genes for roots. Comparison results produced by different sets of reference genes revealed that all these newly recommended reference genes displayed less variation than previous commonly used references genes under the experiment conditions. Thus, selecting appropriate reference genes from RNA-seq datasets leads to identification of reference genes suitable for respective rice tissues under drought and salt stress. The findings offer valuable insights for refining the screening of candidate reference genes under diverse conditions through the RNA-seq database. This refinement serves to improve the accuracy of gene expression in rice under similar conditions.

Racemate ( rac -1) and conglomerate (cong-1) crystals show different phosphorescence behaviour. Rac -1 is a strong excitation-wavelength-tunable photoluminescent material; cong-1 exhibits white-light emission upon temperature change with a CIE 1931 coordinate of (0.33, 0.31).

Maintaining rice yield and reducing nitrogen (N) input are two important targets in sustainable agriculture practices. The adoption of a nitrogen-saving variety (NSV) provides a unique opportunity to achieve this. However, limited options in NSV japonica rice and a lack of information on their responses to N reduction make management decisions difficult. This study aims to explore the responses of yield and nitrogen use efficiency (NUE) in NSV to N reduction. Two newly released NSVs and two popular general varieties (GVs) of japonica rice were field tested in Yangzhou, located at the lower reaches of Yangtze River of China, in two consecutive years. The results showed that for NSVs, with a 40–60% reduction in common practice N rate (300 Kg ha⁻¹), the rice yield could maintain a record average level (p < 0.05), whereas the yield for the GV would drop 20–30% (p < 0.05). This indicates that combining the practices of adoption of NSV and N reduction to 120–180 Kg N ha⁻¹ could balance the yield and N consumption. Moderate N reduction promotes the N accumulation and NUE, and it increases the number of tillers, the productive tiller percentage and the total amount of spikelets in the population, and increases the carbon and N metabolism of the population in the NSV. Compared with GV, NSV showed higher NUE and non-structural carbohydrate re-mobilization in the reduced N rate. The results showed that the practice of N reduction has to adopt NSV at the same time in order to maintain the grain yield level in rice.