Rice Science最新文献

Accurate genomic information is essential for advancing genetic breeding research in specific rice varieties. This study presented a gapless genome assembly of the indica rice cultivar Zhonghui 8015 (ZH8015) using PacBio HiFi, Hi-C, and ONT (Oxford Nanopore Technologies) ultra-long sequencing technologies, annotating 43 037 gene structures. Subsequently, utilizing this genome along with transcriptomic and metabolomic techniques, we explored ZH8015’s response to brown planthopper (BPH) infestation. Continuous transcriptomic sampling indicated significant changes in gene expression levels around 48 h after BPH feeding. Enrichment analysis revealed particularly significant alterations in genes related to reactive oxygen species scavenging and cell wall formation. Metabolomic results demonstrated marked increases in levels of several monosaccharides, which are components of the cell wall and dramatic changes in flavonoid contents. Omics association analysis identified differentially expressed genes associated with key metabolites, shedding light on ZH8015’s response to BPH infestation. In summary, this study constructed a reliable genome sequence resource for ZH8015, and the preliminary multi-omics results will guide future insect-resistant breeding research.

Applying iodine fertilizers to cultivate iodine-rich crops for daily intake is an effective approach for iodine supplementation, especially for aromatic rice. Field experiments were conducted during the early growing seasons of 2021 and 2022 to evaluate the impacts of foliar application of iodine fertilizer on aromatic rice and to explore the optimal iodine fertilizer concentration. At the full heading stage, six different concentrations of sodium iodide solutions of 0% (CK), 0.010% (T1), 0.025% (T2), 0.050% (T3), 0.075% (T4), and 0.100% (T5) were applied to indica aromatic rice cultivars Meixiangzhan 2 and Xiangyaxiangzhan. The results showed that sodium iodide treatments significantly increased the iodine and sodium contents in both leaves and grains. Compared with the CK, the T1 and T2 treatments increased the 2-acetyl-1-pyrroline (2-AP) content in mature grains by 8.41%‒101.66% and 13.58%‒ 74.60%, respectively. Improvements in the contents of 1-pyrroline-5-carboxylic acid, proline, 1-pyrroline, and methylglyoxal, as well as the activity of proline dehydrogenase were also detected. Additionally, sodium iodide treatments remarkably decreased the chalky grain rate, chalkiness area, and chalkiness degree of aromatic rice, with the T2 treatment exhibiting a 17.79%‒47.42% decrease in chalkiness degree compared with the CK. Meanwhile, T1 and T2 treatments showed beneficial impacts on chlorophyll content, photosynthetic characteristics, and yield components, while T3, T4, and T5 treatments exhibited adverse effects on leaf and grain yields. The linear discriminant analysis revealed significant differences between treatments. The correlation analysis and piecewise structural equation modeling showed that the iodine and sodium influenced the photosynthetic characteristics and chlorophyll content of the leaves, thereby regulating the 2-AP biosynthesis and yield components, ultimately affecting the 2-AP content and yield. Overall, this study suggests that foliar application of 0.025% sodium iodide is an effective method to enrich the iodine content in rice grains, improve the grain aroma and appearance quality of aromatic rice, without detrimental effects on grain yield.

Glutinous rice (Oryza sativa var. glutinosa) stands out as one of the most popular rice varieties globally, amidst thousands of rice cultivars. Its increasing popularity is attributed to its rich nutritional compositions and health benefits. This review aims to summarize the nutritional compositions, volatile compounds, and health benefits of glutinous rice. Further, in-depth studies are necessary to explore the utilization of glutinous rice in enhancing processing technologies and developing new food products. Glutinous rice has been shown to possess numerous health benefits, including antioxidant activity, bioactive compounds, anti-cancer properties, anti-inflammatory effects, anti-diabetic potential, and cholesterol-lowering effects. Besides its nutritional compositions, the major volatile compounds identified in glutinous rice could serve as a functional food for human consumption. Emerging processing technologies related to glutinous rice are elaborated to improve the latest developments for incorporating them into various food products.

Rice cooking and eating qualities (CEQ) are mainly determined by cooked rice textural parameters and starch physicochemical properties. However, the genetic bases of grain texture and starch properties in rice have not been fully understood. We conducted a genome-wide association study for apparent amylose content (AAC), starch pasting viscosities, and cooked rice textural parameters using 279 indica rice accessions from the 3 000 Rice Genome Project. We identified 26 QTLs in the whole population and detected single nucleotide polymorphisms (SNPs) with the lowest P-value at the Waxy (Wx) locus for all traits except pasting temperature and cohesiveness. Additionally, we detected significant SNPs at the SUBSTANDARD STARCH GRAIN6 (SSG6) locus for AAC, setback (SB), hardness, adhesiveness, chewiness (CHEW), gumminess (GUM), and resilience. We subsequently divided the population using a SNP adjacent to the Waxy locus, and identified 23 QTLs and 12 QTLs in two sub-panels, Wx^T and Wx^A, respectively. In these sub-panels, SSG6 was also identified to be associated with pasting parameters, including peak viscosity, hot paste viscosity, cold paste viscosity, and consistency viscosity. Furthermore, a candidate gene encoding monosaccharide transporter 5 (OsMST5) was identified to be associated with AAC, breakdown, SB, CHEW, and GUM. In total, 39 QTLs were co-localized with known genes or previously reported QTLs. These identified genes and QTLs provide valuable information for genetic manipulation to improve rice CEQ.

This study aims to investigate grain quality and nutritional values of rice (Pokkali, a salt-tolerant cultivar; RD73, a new cultivar improved from KDML105 introgressed with Saltol QTL from Pokkali, and KDML105, a moderately salt-susceptible cultivar) grown under non-saline (0.04–0.87 dS/m) and slightly saline (1.08–4.83 dS/m) field conditions. The results revealed that salinity caused significant reduction in grain size but significant increments in reducing sugar and total protein contents in the grains. Nevertheless, the amounts of starch in the grains of KDML105 and Pokkali rice genotypes were unaffected by the stress. The starch granule size distribution was also unaffected by salinity. Interestingly, only starch from Pokkali was significantly diminished in amylose content, from 19.18% to 16.99%. Accordingly, parameters relating to starch gelatinization, retrogradation, and pasting properties of KDML105 and RD73 were unaffected by salinity; only Pokkali showed a significant increase in percentage of retrogradation along with a significant reduction in gelatinization enthalpy. In the saline field, total phenolic content and antioxidant capacity in the grains of all rice cultivars tended to increase, particularly in Pokkali. On average, essential element contents in grains from the saline-treated plants showed a 33%, 32%, 32%, 22%, 20%, 11%, and 10% increase in total P, N, K, Mg, Zn, Fe, and Ca content, respectively. Interestingly, total Fe content exhibited the greatest percentage of increments in KDML105 (187%). Taken together, cultivation of rice in the slightly saline field did not alter its eating and cooking qualities, while enhanced some nutritional properties such as proteins, minerals, and secondary metabolites like phenolic compounds.

The basic region/leucine zipper (bZIP) transcription factors play important roles in plant development and responses to abiotic and biotic stresses. OsbZIP53 regulates resistance to Magnaporthe oryzae in rice by analyzing APIP5-RNAi transgenic plants. To further investigate the biological functions of OsbZIP53, we generated osbzip53 mutants using CRISPR/Cas9 editing and also constructed OsbZIP53 over-expression transgenic plants. Comprehensive analysis of phenotypical, physiological, and transcriptional data showed that knocking-out OsbZIP53 not only improved disease resistance by inducing a hypersensitivity response in plants, but also regulated the immune response through the salicylic acid pathway. Specifically, disrupting OsbZIP53 increased H₂O₂ accumulation by promoting reactive oxygen species generation through up-regulation of several respiratory burst oxidase homologs (Osrboh genes) and weakened H₂O₂ degradation by directly targeting OsMYBS1. In addition, the growth of osbzip53 mutants was seriously impaired, while OsbZIP53 over-expression lines displayed a similar phenotype to the wild type, suggesting that OsbZIP53 has a balancing effect on rice immune response and growth.

Rice (Oryza sativa L.) stands as the most significantly influential food crop in the developing world, with its total production and yield stability affected by environmental stress. Drought stress impacts about 45% of the world’s rice area, affecting plants at molecular, biochemical, physiological, and phenotypic levels. The conventional breeding method, predominantly employing single pedigree selection, has been widely utilized in breeding numerous drought-tolerant rice varieties since the Green Revolution. With rapid progress in plant molecular biology, hundreds of drought-tolerant QTLs/genes have been identified and tested in rice crops under both indoor and field conditions. Several genes have been introgressed into elite germplasm to develop commercially accepted drought-tolerant varieties, resulting in the development of several drought-tolerant rice varieties through marker-assisted selection and genetically engineered approaches. This review provides up-to-date information on proof-of-concept genes and breeding methods in the molecular breeding era, offering guidance for rice breeders to develop drought-tolerant rice varieties.