Rice最新文献

Ratoon rice (RR), recognized as an efficient method of rice cultivation, plays a crucial role in the food production system. By enabling two harvests-during the main season rice (MSR) and the ratoon season rice (RSR)-from a single planting, this cropping system significantly enhances the utilization of land and temperature-solar radiation resources, thereby providing essential support for food security. However, the yield formation of RSR is constrained by several factors, including the adaptability of the rice variety, nitrogen fertilizer management strategies, and the uneven distribution of temperature and solar radiation resources, which collectively hinder the actual realization of its yield potential. This research first employed a meta-analysis approach to identify the optimal nitrogen management practices for ratoon rice. Through multi-location field experiments, high-yielding ratoon rice varieties with strong ecological adaptability were selected. Then, the selected high-yielding and adaptable varieties were cultivated under field conditions by using the optimal nitrogen management practices to compare the yield formation differences and underlying mechanisms among the MSR, RSR, and late-season rice (LSR) with synchronous heading. The research findings indicated that the yield of RSR was significantly lower compared to both MSR and LSR with delayed panicle emergence. Nevertheless, considering that its growth period constituted only 53.52% and 55.47% of the growth periods of MSR and LSR with delayed panicle emergence, respectively. Its daily grain yield (DGY) was 28.33% and 13.56% higher than that of MSR and LSR with delayed panicle emergence. Furthermore, RSR exhibited significant advantages in terms of effective panicle (EP) and seed setting percentage (SSP), although its number of grains per panicle (NP) and 1000-grain weight (TGW) were notably lower than those of MSR and LSR. Subsequent analysis demonstrated that enhancing the utilization efficiency of temperature and solar radiation resources can significantly increase the EP and SSP in RSR. By extending the days before flowering and augmenting accumulated temperature and radiation before flowering, there is a significant notable increase in NP and TGW, thereby overcoming the yield limitations. This study offers a theoretical foundation and technical support for the high-yield and efficient cultivation of RSR.

Rice grain quality improvement is closely linked to economic development, local dietary habits, and traditional culture. Despite significant advances in breeding over the past decade, enhancing grain quality remains a major challenge. Here, we evaluated 315 newly sequenced rice varieties (163 japonica and 152 indica) to assess milling quality (e.g., head rice yield, HRY), cooking quality (e.g., amylose content, AC), and nutritional quality (e.g., protein content, PC). Clear regional differences were observed: Yunnan and Jiangsu contributed more high-quality japonica varieties, whereas Guangdong and Guizhou produced more high-quality indica varieties. A genome-wide association study identified several QTLs and putative candidate genes associated with grain quality traits. A composite haplotype (Hap1) of the Wx gene, defined by both coding and intronic polymorphisms, was associated with low AC and high HRY. Additional putative candidate genes were suggested, including LOC_Os04g40760 and LOC_Os04g40780 (HRY), LOC_Os06g04080 (AC), and LOC_Os06g20020 (PC), with expression differences observed across growth stages. Superior haplotypes, such as Hap1 of LOC_Os04g40760 and LOC_Os04g40780, are rare in wild rice but have increased in frequency during domestication, indicating strong selection. Collectively, these findings highlight regional disparities in the prioritisation of grain quality traits and provide preliminary genomic resources and hypotheses for future functional studies and marker-assisted breeding.

Although the yield and resistance of cultivated rice have been significantly enhanced since domestication, its genetic basis remains narrow, with many beneficial genes having been lost. Weedy rice is an important source of genetic material for improving rice and provides valuable germplasm resources for identifying excellent genes. In our study, we constructed an F₂ genetic population by crossing the weedy rice variety LM8, which has extremely small grains, with cultivated rice. High-density genetic maps were constructed using whole-genome sequencing. Five grain shape traits were observed in the F₂ population, including grain length, grain width, grain thickness, length width ratio and thousand grain weight. The phenotype data were found to be consistent with a normal distribution. Through linkage analysis of the phenotype and genetic maps, a total of 14 QTL loci were identified, one of which was associated with grain length. Grain length values ranged from 5.32 to 11.14 mm. The associated locus was located at 18.81-18.87 Mb on chromosome 3, and accounted for 19.88% of the total phenotypic variation. The BC₁F₂ population was constructed using Bulked Segregant Analysis (BSA) sequencing to locate the grain length gene. The ORUFILM03g000096 gene, which is homologous to the Os03g0427300 gene of Nipponbare, was identified as the grain length gene. According to the annotation of the known genes, the ORUFILM03g000096 gene belongs to the Glutelin (GLU) gene family, which is generally associated with rice quality. A systematic investigation of the expression profile of ORUFILM03g000096 gene using the Rice Expression Profile (RiceXPro) database showed high expression in young panicles. Evolutionary tree analysis revealed a closer evolutionary relationship with the Japanese gene sequence. Hplotype analysis of the gene in the hybrid offspring indicated that a non-synonymous mutation (G-A), located 861 bp downstream of the ATG site in the third exon of the candidate gene, affected the grain length. It is hypothesized that this gene plays a crucial role in grain length growth and enhances rice quality.

GDP-L-galactose phosphorylase (GGP) is a key rate-limiting enzyme in the ascorbic acid synthesis pathway, and it plays a crucial role in regulating ascorbic acid metabolism and redox balance. The upstream open reading frame (uORF) in the 5' untranslated region of the GGP gene typically suppresses translation efficiency, reducing vitamin C content. In this study, GGP uORF in rice was identified, and seven GGP uORF allele variants AL1-AL7 were generated by CRISPR/Cas9 technology; then, the effects of these variations on AsA content and osmotic stress resistance were evaluated. The AsA content of the seven mutant plants was 1.80-3.08 times greater than that of the control, and the increase of AL4 mutant was the greatest. Protoplast assays confirmed that the OsGGP uORF inhibits downstream ORF translation. Osmotic stress experiments revealed that in the mutant lines, both the activities of enzymes involved in reactive oxygen species (ROS) scavenging and the proline (Pro) content were significantly increased, while the levels of peroxides were significantly decreased. These results demonstrate that mutation of the GGP uORF significantly increases translation efficiency, AsA content, and the ability of rice to reduce ROS levels, restore osmotic balance, and improve ROS scavenging capacity under osmotic stress. This study reports the regulated osmotic stress of the GGP uORF in monocotyledonous plants for the first time and has created a variety of allelic variation germplasm resources. It provides a novel approach for improving AsA content and tolerance to salt stress in rice and other monocots via genetic approaches.

Rice blast disease is one of the most destructive rice diseases worldwide. Rice MicroRNAs (miRNAs) play an essential role in immunity against blast fungus Magnaporthe oryzae. However, it remains unclear which miRNAs are involved in the three layers of rice-M. oryzae interaction, including pathogen associated molecular patterns (PAMPs)-triggered immunity (PTI), effector-triggered susceptibility (ETS), and effector-triggered immunity (ETI). In this study, we performed small RNA-sequencing to systemically identify miRNAs regulating PTI, ETS, and ETI in rice-M. oryzae interaction. A totally 441 miRNAs were identified, with 13, 30, and 14 miRNAs screened out and classified as regulators of PTI, ETS, and ETI, respectively. We investigated and confirmed the roles of 9 previously reported miRNAs and an uncharacterized miRNA, miR408-5p, in the three interaction processes. We demonstrated that miR1320-5p positively regulated PTI; miR396 family members and miR164a improved, whereas miR171b and miR172a suppressed ETS; miR166a enhanced, whereas miR169a and miR396 family members suppressed ETI. Moreover, we demonstrated that miR397b and miR408-5p enhanced rice susceptibility by promoting ETS and suppressing ETI; miR398b enhanced rice resistance by promoting both PTI and ETI while suppressing ETS. Our findings figured a miRNA-mediated regulatory network in which distinct miRNAs modulate PTI, ETS, and ETI against M. oryzae. This study provides new sight into the regulation mechanism of plant disease resistance.

Background: Fragrance is a premium trait of grain quality in the traditional, Jasmine-style rice (Oryza sativa L.) variety Phka Rumduol (PRD). Rice fragrance is a combination of various volatile compounds with characteristic odours and flavours that can be traced back to fatty acids. Given the complexity of fragrance phenotype, the use of a robust phenotyping platform in identifying metabolite quantitative trait loci (mQTL) is essential to providing the most suitable set of genetic markers associated with desirable fragrance metabolites and their fatty acid origins in PRD-derived rice breeding lines.

Results: Using combined untargeted metabolomics via GC×GC-TOF-MS, targeted fatty acid analysis with GC-MS, mQTL for individual volatile compounds and fatty acids were identified in a SNP-genotyped F₆ recombinant-inbred rice population developed from a cross between PRD and Thmar Krem (TMK; non-fragrant). This study confirmed the genetic link between 2-acetyl-1-pyrroline and its derivatives with SNPs on chromosomes 8, 3, 4, and 1 and revealed novel mQTLs on chromosomes 2 and 6. MQTLs identified for saturated aldehydes, alcohols, ketones and alkylfurans co-localised on chromosomes 1, 3, and 6 were mainly contributed by PRD, whereas sulfur-containing compounds were contributed by TMK and associated with mQTLs on chromosomes 5 and 6. Oleic and linoleic acid composition were associated with a common QTL on chromosome 7.

Conclusion: Our results demonstrate the ability of untargeted metabolomics to reveal the uniqueness of the fragrance profile of individual rice breeding lines in a mapping population which would allow for improved precision in marker-assisted selection. The various mQTLs verified in this study reaffirm the need for more in-depth metabolite-based selection incorporated in rice breeding. The information from this research is valuable for rice breeding and food quality improvement programs.

The limited availability of ideal cadmium (Cd) hyperaccumulating plants remains a significant challenge for phytoremediating Cd-contaminated soils. This study aims to find out if the high biomass giant rice can be a suitable phytoremediation candidate for Cd-contaminated paddy fields and to elucidate physiological mechanisms relative to low or high Cd accumulation. Soil column and lysimeter tests were conducted with giant and normal species of rice under different water conditions. Cd distribution in different parts of root and shoots were determined. Under sustained flooding in column tests or keeping soil moist after the tillering stage in lysimeter tests, Cd contents in the grain of giant rice were very low. The Cd bioconcentration factor (BCF) of grain of giant rice (0.015-0.034) were significantly lower than those of normal rice (0.088-0.099), while BCF of root was in the reversed trend. Of the Cd in giant rice roots, 23.5% was trapped by the iron plaque on the root surface, compared 11.7% for normal rice. More Fe-O, -COOH functional groups in giant rice roots were confirmed by FTIR spectra. Under semi-dry condition, Cd contents in giant rice were very significantly increased, BCF straw in regenerated giant rice reached 13.4. Cd in shoots were accumulated in basal stems of the giant rice, the phytoextraction rate reached 18.7% of total Cd in topsoil, compared to 9.6% for giant Napier grass (Pennisetum hybridum). Therefore, the giant rice is a unique crop who can highly produce safe rice under wet conditions in the first half year and meanwhile by regenerating it can efficiently phytoextract Cd in the soil under semi-dry condition with a low labor input and carbon emission.