Rice Science最新文献

Traditional rice varieties have been widely cultivated and popularly consumed by Asian people for a very long time and have recently garnered increased consumer concern. Traditional or indigenous rice varieties are known to be rich in a wide range of bioactive compounds, particularly phenolic compounds, flavonoids, tannins, anthocyanins, proanthocyanidins, phytic acids, and γ-oryzanol. We have identified 32 phenolic acids, including hydroxycinnamic acid derivatives, and 7 different flavonoids in rice varieties. These bioactive compounds have unique physiological effects on human health. Additionally, rice grains exhibit nutraceutical potential for antidiabetic, antiarthritic, anti-inflammatory, antibacterial, and antitumor activities. In this review, we critically analyzed the bioactive components of traditional rice and their nutraceutical potential in protecting against harmful microbial activities. To ensure that future generations have access to these beneficial substances, it is crucial to preserve traditional rice varieties.

Due to climate change, extreme heat stress events have become more frequent, adversely affecting rice yield and grain quality. The accumulation and translocation of dry matter and nitrogen substances are essential for rice yield and grain quality. To assess the impact of high temperature stress (HTS) at the early panicle initiation (EPI) stage on the accumulation, transportation, and distribution of dry matter and nitrogen substances in various organs of rice, as well as the resulting effects on rice yield and grain quality, pot experiments were conducted using an indica rice cultivar Yangdao 6 (YD6) and a japonica rice cultivar Jinxiangyu 1 (JXY1) under both normal temperature (32 ºC / 26 ºC) and high temperature (38 ºC / 29 ºC) conditions. The results indicated that exposure to HTS at the EPI stage significantly decreased rice yield by reducing spikelet number per panicle, grain-filling rate, and grain weight. However, it improved the nutritional quality of rice grains by increasing protein and amylose contents. The reduction in nitrogen and dry matter accumulation accounted for the changes in spikelet number per panicle, grain-filling rate, and grain size. Under HTS, the decrease in nitrogen accumulation accompanied by the reduction in dry matter may be due to the down-regulation of leaf net photosynthesis and senescence, as evidenced by the decrease in nitrogen content. Furthermore, the decrease in sink size limited the translocation of dry matter and nitrogen substances to grains, which was closely related to the reduction in grain weight and the deterioration of grain quality. These findings significantly contribute to our understanding of the mechanisms of HTS on grain yield and quality formation from the perspective of dry matter and nitrogen accumulation and translocation. Further efforts are needed to improve the adaptability of rice varieties to climate change in the near future.

The nutritional quality of rice is a major concern, along with the need to enhance productivity to feed the continuously growing population. Therefore, there is a requirement to breed high-yielding rice varieties with improved nutritional quality that can help combat malnutrition, a global health issue. Undoubtedly, breeding approaches have played a significant role in increasing rice yield while enhancing its nutritional content. In addition to traditional breeding techniques, other recent approaches, such as genetic engineering, gene editing, omics methods, and agronomic practices, must also be employed to meet the nutritional needs of the current population. In this review, we offered detailed information on the development of nutritionally improved rice varieties through the enhancement of protein content, micro- and macronutrients, vitamins, and oil quality using genetic engineering approaches. We also identified QTLs associated with amino acids, proteins, and micronutrients in rice. Furthermore, omics approaches provide a range of tools and techniques for effectively exploring resources and understanding the molecular mechanisms involved in trait development. Omics branches, including transcriptomics, proteomics, ionomics, and metabolomics, are efficiently utilized for improving rice nutrition. Therefore, by utilizing the information obtained from these techniques and incorporating all of these recent approaches, we can effectively modify the rice genome, directly enhancing the nutritional value of rice varieties. This will help address the challenges of malnutrition in the years to come.

This study aimed to investigate the responses in rice (Oryza sativa cv. Osmancik 97) production and grain zinc (Zn) accumulation to combined Zn and sulfur (S) fertilization. The experiment was designed as a factorial experiment with two Zn and three S concentrations applied to the soil in a completely randomized design with four replications. The plants were grown under greenhouse conditions at low (0.25 mg/kg) and adequate (5 mg/kg) Zn rates combined with S (CaSO₄·2H₂O) application (low, 2.5 mg/kg; moderate, 10 mg/kg, and adequate, 50 mg/kg). The lowest rate of S at adequate soil Zn treatment increased grain yield by 68% compared with the same S rate at low Zn supply. Plants with the adequate S rate at low Zn and adequate Zn supply produced the highest grain yield, with increases of 247% and 143% compared with low S rate at low Zn and adequate Zn supply, respectively. The concentration of grain Zn and S responded differently to the applied S rates depending on the soil Zn condition. The highest grain Zn concentration, reaching 41.5 mg/kg, was observed when adequate Zn was supplied at the low S rate. Conversely, the adequate S rate at the low soil Zn conditions yielded the highest grain S concentration. The total grain Zn uptake per plant showed particular increases in grain Zn yield when adequate S rates were applied, showing increases of 208% and 111% compared with low S rate under low and adequate soil Zn conditions, respectively. The results indicated that the synergistic application of soil Zn and S improves grain production and grain Zn yield. These results highlight the importance of total grain Zn yield in addition to grain Zn concentration, especially under the growth conditions where grain yield shows particular increases as grain Zn is diluted due to increased grain yield by increasing S fertilization.

An EMS (ethy methanesulfonate)-induced lethal etiolated (le) mutant obtained from the rice variety Zhongjian 100 was characterized by lethal etiolated phenotypes, with significantly reduced levels of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids. Additionally, the mutant displayed a significantly decreased number of chloroplast grana, along with irregular and less-stacked grana lamellae. The le mutant showed markedly diminished root length, root surface area, and root volume compared with the wild type. It also exhibited significantly lower catalase activity and total protein content, while peroxidase activity was significantly higher. Using the map-based cloning method, we successfully mapped the LE gene to a 48-kb interval between markers RM16107 and RM16110 on rice chromosome 3. A mutation (from T to C) was identified at nucleotide position 692 bp of LOC_Os03g59640 (ChlD), resulting in a change from leucine to proline. By crossing HM133 (a pale green mutant with a single-base substitution of A for G in exon 10 of ChlD subunit) with a heterozygous line of le (LEle), we obtained two plant lines heterozygous at both the LE and HM133 loci. Among 15 transgenic plants, 3 complementation lines displayed normal leaf color with significantly higher total chlorophyll, chlorophyll a, and chlorophyll b contents. The mutation in le led to a lethal etiolated phenotype, which has not been observed in other ChlD mutants. The mutation in the AAA⁺ domain of ChlD disrupted the interaction of ChlD^le with ChlI as demonstrated by a yeast two-hybrid assay, leading to the loss of ChlD function and hindering chlorophyll synthesis and chloroplast development. Consequently, this disruption is responsible for the lethal etiolated phenotype in the mutant.

Rice blast is regarded as one of the major diseases of rice. Screening rice genotypes with high resistance to rice blast is a key strategy for ensuring global food security. Unmanned aerial vehicles (UAV)-based imaging, coupled with deep learning, can acquire high-throughput imagery related to rice blast infection. In this study, we developed a segmented detection model (called RiceblastSegMask) for rice blast detection and resistance evaluation. The feasibility of different backbones and target detection models was further investigated. RiceblastSegMask is a two-stage instance segmentation model, comprising an image-denoising backbone network, a feature pyramid, a trinomial tree fine-grained feature extraction combination network, and an image pixel codec module. The results showed that the model combining the image-denoising and fine-grained feature extraction based on the Swin Transformer and the feature pixel matching feature labels with the trinomial tree recursive algorithm performed the best. The overall accuracy for instance segmentation of RiceblastSegMask reached 97.56%, and it demonstrated a satisfactory accuracy of 90.29% for grading unique resistance to rice blast. These results indicated that low-altitude remote sensing using UAV, in conjunction with the proposed RiceblastSegMask model, can efficiently calculate the extent of rice blast infection, offering a new phenotypic tool for evaluating rice blast resistance on a field scale in rice breeding programs.

Given the consistent release of zinc oxide (ZnO) nanoparticles into the environment, it is urgent to study their impact on plants in depth. In this study, grains of rice were treated with two different concentrations of ZnO nanoparticles (NP-ZnO, 10 and 100 mg/L), and their bulk counterpart (B-ZnO) were used to evaluate whether ZnO action could depend on particle size. To test this hypothesis, root growth and development assessment, oxidative stress parameters, indole-3-acetic acid (IAA) content and molecules/enzymes involved in IAA metabolism were analyzed. In situ localization of Zn in control and treated roots was also performed. Though Zn was visible inside root cells only following nanoparticle treatment, both materials (NP-ZnO and B-ZnO) were able to affect seedling growth and root morphology, with alteration in the concentration/pattern of localization of oxidative stress markers and with a different action depending on particle size. In addition, only ZnO supplied as bulk material induced a significant increase in both IAA concentration and lateral root density, supporting our hypothesis that bulk particles might enhance lateral root development through the rise of IAA concentration. Apparently, IAA concentration was influenced more by the activity of the catabolic peroxidases than by the protective action of phenols.

Ustiloxins are vital cyclopeptide mycotoxins originally isolated from rice false smut balls that form in rice spikelets infected by the fungal pathogen Ustilaginoidea virens. The toxicity of the water extract of rice false smut balls (RBWE) remains to be investigated. Studies have shown that RBWE may be toxic to animals, but toxicological evidence is still lacking. In this study, we found that the IC₅₀ values of RBWE to BNL CL.2 cells at 24 and 48 h were 40.02 and 30.11 μg/mL, respectively, with positive correlations with dose toxicity and time toxicity. After treatment with RBWE, the number of BNL CL.2 cells decreased significantly, and the morphology of BNL CL.2 cells showed atrophy and wall detachment. RBWE induced DNA presynthesis phase arrest of BNL CL.2 cells, increased the proportion of apoptotic cells and inhibited cell proliferation. RBWE up-regulated reactive oxygen species (ROS) levels and lowered mitochondrial membrane potentials. Additionally, Western blot and qRT-PCR results suggested that RBWE exerted the above effects by promoting the Nrf2/HO-1 and caspase-induced apoptosis pathways in vitro and in vivo. The contents of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and total bile acids in the serum of mice from Institute of Cancer were significantly up-regulated by RBWE. At the same time, RBWE can lead to increases in ROS and malondialdehyde contents, decreases in contents of oxidized glutathione, glutathione and reduced glutathione, as well as decrease in catalase and superoxide dismutase activities in mouse liver tissues, demonstrating that oxidative stress occurred in mice. Moreover, liver damage was further detected by haematoxylin-eosin staining and electron microscopy to verify the damage to the mice caused by RBWE. In general, RBWE may cause hepatotoxicity in vivo and in vitro via the apoptosis pathway, which provides a reference for hepatotoxicity and its mechanism of action.