Cultivated Rice Varieties Research Articles

Morphological, physiological, and biochemical responses of rice (Oryza sativa L.) varieties to drought stress via regulating respiration and ROS metabolism during germination

Germination marks a pivotal and sensitive phase in the life cycle of crops, with drought stress, precipitated by water scarcity, posing a significant impediment to the germination process in rice. Despite this, the regulation mechanism of respiratory and reactive oxygen species (ROS) metabolism during rice germination under drought stress remains to be fully elucidated. This manuscript presents an integrative analysis encompassing morphological, physiological, biochemical, and molecular attributes of germinated seeds from a cultivated drought-sensitive rice variety (JN10) and a drought-resistant rice variety (NG36). Our findings revealed that drought stress adversely affected the germination of both rice varieties, with NG36 exhibiting a more rapid germination rate compared to JN10 under such stress conditions. This differential response was attributed to the heightened activity of key enzymes, elevated levels of metabolic intermediates, and upregulated expression of genes encoding enzymes involved in ROS and respiratory metabolic pathways in NG36. To further dissect the interplay between these metabolic pathways, we selected specific enzyme activities for detailed examination. Notably, a robust positive linear correlation was established among phosphofructokinase (PFK), α-ketoglutarate dehydrogenase (KGDH), citrate synthase (CS), and isocitrate dehydrogenase (ICDH) in NG36. This correlation underscores the pivotal role of glycolytic pathways, particularly the tricarboxylic acid (TCA) cycle, in conferring drought resistance to NG36 during the germination phase under drought stress. To encapsulate our findings, the results of this investigation suggest that the rice cultivar NG36 manifests a heightened degree of drought tolerance relative to JN10. This is primarily achieved through the adept modulation of its respiratory metabolic pathways and the stringent preservation of ROS homeostasis during the germination phase under conditions of water deficit. These revelations provide unprecedented insights into the intricate regulatory mechanisms that subserve rice's drought resistance, potentially paving the way for the development of novel strategies in the breeding of rice cultivars with improved drought resilience.

Classification of Rice Grains by Image Processing

General Background: The assessment of the surface quality of pre-treated rice grains is crucial for determining their market acceptability, storage stability, processing quality, and overall consumer satisfaction. Traditional evaluation methods are often time-consuming and yield subjective classifications. Specific Background: The lack of a comprehensive tagged image dataset hinders the application of advanced convolutional neural networks (CNN) for detailed damage classification of healthy rice grains. Knowledge Gap: Existing datasets and methods limit the effective exploration of sophisticated CNN models for categorizing rice types, particularly in identifying subtle damage characteristics. Aims: The study aims to create a robust rice grain classification system using image processing techniques, primarily deep learning algorithms, to improve the classification of rice varieties. Results: Utilizing a dataset of 75,000 images across five widely cultivated rice varieties in Turkey, we achieved classification accuracies of 100% for CNN, 99.95% for deep neural networks (DNN), and 99.87% for artificial neural networks (ANN). Novelty: The proposed approach represents a significant advancement in rice classification technology, employing a combination of image acquisition, feature extraction, and machine learning to streamline the process, effectively addressing the challenges faced in traditional methods. Implications: The findings underscore the potential for improved sorting and grading efficiency in the rice industry, facilitating better market outcomes and consumer satisfaction through enhanced quality control Highlights: Innovative: Uses CNN for accurate rice variety classification. Data-Driven: Analyzes 75,000 images for enhanced quality evaluation. Impactful: Increases efficiency in sorting and grading processes. Keywords: Rice Classification, Image Processing, CNN, Machine Learning, Agricultural Technology

New persistent plant RNA virus carries mutations to weaken viral suppression of antiviral RNA interference.

Persistent plant viruses are widespread in natural ecosystems. However, little is known about why persistent infection with these viruses may cause little or no harm to their host. Here, we discovered a new polerovirus that persistently infected wild rice plants by deep sequencing and assembly of virus-derived small-interfering RNAs (siRNAs). The new virus was named Rice tiller inhibition virus 2 (RTIV2) based on the symptoms developed in cultivated rice varieties following Agrobacterium-mediated inoculation with an infectious RTIV2 clone. We showed that RTIV2 infection induced antiviral RNA interference (RNAi) in both the wild and cultivated rice plants as well as Nicotiana benthamiana. It is known that virulent virus infection in plants depends on effective suppression of antiviral RNAi by viral suppressors of RNAi (VSRs). Notably, the P0 protein of RTIV2 exhibited weak VSR activity and carries alanine substitutions of two amino acids broadly conserved among diverse poleroviruses. Mixed infection with umbraviruses enhanced RTIV2 accumulation and/or enabled its mechanical transmission in N. benthamiana. Moreover, replacing the alanine at either one or both positions of RTIV2 P0 enhanced the VSR activity in a co-infiltration assay, and RTIV2 mutants carrying the corresponding substitutions replicated to significantly higher levels in both rice and N. benthamiana plants. Together, our findings show that as a persistent plant virus, RTIV2 carries specific mutations in its VSR gene to weaken viral suppression of antiviral RNAi. Our work reveals a new strategy for persistent viruses to maintain long-term infection by weak suppression of the host defence response.

Endogenous γ-Aminobutyric Acid Accumulation Enhances Salinity Tolerance in Rice

Rice is an important food crop worldwide but is usually susceptible to saline stress. When grown on soil with excessive salt, rice plants experience osmotic, ionic, and oxidative stresses that adversely affect growth performance. γ-Aminobutyric acid (GABA) is a nonproteinogenic amino acid that plays an important role in the metabolic activities of organisms. Glutamate decarboxylase (GAD) is the rate-limiting enzyme in GABA metabolism. Here, we genetically modified rice GAD by overexpression or CRISPR-mediated genome editing. These lines, named gad3-ox1 and gad3-ox2 or gad1/3-ko, were used to explore the effects of endogenous GABA accumulation on salt tolerance in rice. Both the gad3-ox1 and gad3-ox2 lines exhibited significant accumulation of the GABA content, whereas the gad1/3-ko line presented a reduced GABA content in vivo. Notably, the two overexpression lines were markedly resistant to salt stress compared with the wild-type and knockout lines. Furthermore, our results demonstrated that endogenous GABA accumulation in the gad3-ox1 and gad3-ox2 lines increased the contents of antioxidant substances and osmotic regulators, decreased the content of membrane lipid peroxidation products and the Na+ content, and resulted in strong tolerance to salt stress. Together, these data provide a theoretical basis for cultivating rice varieties with strong salt tolerance.

Evaluation of Sheath Blight Resistance in Diverse Rice Varieties Under Artificial Inoculation and Field Conditions

Rice (Oryza sativa L.) a vital food crop for nearly half of the global population, facing significant threats from various biotic and abiotic stresses. Among biotic stresses, diseases pose the most common challenge. Sheath blight, caused by soil-borne fungal pathogen Rhizoctonia Solani Kühn (R. solani), is a major concern, leading to substantial damage to rice and cereal crops worldwide. This study evaluated sheath blight resistance across diverse rice varieties, including short grain, long grain, aromatic, hybrid, and wild types, under both artificial inoculation and field conditions. Ten host plant species were assessed for resistance to sheath blight caused by Rhizoctonia Solani, using physiological screening one-week post-inoculation. The highly virulent R. solani isolate (AG-1 IA anastomosis group) was cultured on PDA media, covering the entire plate 3 to 5 days. Screening of cultivated rice varieties, was conducted using field conditions and humidified chamber methods, with results confirmed through molecular characterization. Among the ten cultivated rice varieties, Arize 6444 and Dhanya 748 exhibited the lowest disease index, classifying them as moderately resistant. In contrast, Kalanamak and Pusa Basmati were highly susceptible, displaying high disease indices. Among wild rice accessions, Oryza rufipogon showed a disease index of five or less. Visual ratings indicated the highest susceptibility in Kalanamak, followed by Pusa Basmati and Swarna sub-1, while the lowest visual ratings were observed in wild rice accessions Oryza australiensis and Oryza rufipogon across all tested hosts. The findings underscore the importance of identifying resistant rice varieties to manage sheath blight effectively. The moderately resistant cultivars and wild rice accessions identified in this study offer valuable genetic resources for breeding programs aimed at enhancing sheath blight resistance in rice.

Research Progress on Mechanical Strength of Rice Stalks.

As one of the most important food crops in the world, rice yield is directly related to national food security. Lodging is one of the most important factors restricting rice production, and the cultivation of rice varieties with lodging resistance is of great significance in rice breeding. The lodging resistance of rice is directly related to the mechanical strength of the stalks. In this paper, we reviewed the cell wall structure, its components, and its genetic regulatory mechanism, which improved the regulatory network of rice stalk mechanical strength. Meanwhile, we analyzed the new progress in genetic breeding and put forward some scientific problems that need to be solved in this field in order to provide theoretical support for the improvement and application of rice breeding.

Genome-wide characterization and functional analysis of heat shock transcription factors in wild and cultivated rice (Oryza sativa L.)

Due to domestication, the genetic diversity in cultivated rice is lower than that of wild rice species. Recent progress in sequencing the genomes of wild and cultivated rice genus is an important step in identifying their genetic differences associated with abiotic and biotic stresses-resistant ability. Thus, in this study, heat shock transcription factor (Hsf) genes in 6 wild rice accessions, including Oryza barthii, Oryza glumaepatula, Oryza meridionalis, Oryza nivara, Oryza punctate and Oryza rufipogon, and 1 cultivated rice variety Nipponbare were firstly identified, and the evolution of rice Hsf genes were analyzed. Totally, 22, 23, 24, 24, 25, 25 and 25 Hsf genes were identified in the 7 tested rice genomes, Oryza barthii, Oryza glumaepatula, Oryza meridionalis, Oryza nivara, Oryza punctate, Oryza rufipogon and Oryza sativa, respectively. The evolutionary analysis of Hsf genes revealed that Oryza rufipogon was the immediate ancestral progenitor of Oryza sativa. The variation in the number of Hsf genes between wild and cultivated rice genotypes was mainly due to segmental duplication and whole genome duplication (WGD) events, which might contribute to the different stress-tolerant ability between the wild and cultivated rice varieties. Secondly, the function of the Hsf genes in wild and cultivated rice in response to salinity stress was compared. Under salt stress, four Hsf genes, HsfA2b, HsfB4b, HsfB4c and HsfB4d, were exclusively down-regulated in Oryza rufipogon shoots. Whilst, another four Hsf genes, HsfA7a, HsfB2c, HsfC1b and HsfC2b, were up-regulated in the shoots of both the cultivated rice and its ancestral progenitor Oryza rufipogon. Meanwhile, genomic comparison results showed that 1, 1, 5 and 5 nsSNPs were detected in these 4 Hsf genes respectively, which might alter the functions of these genes. RT-qPCR results further confirmed the expression profile of one of these 4 Hsf genes, HsfB2c. The expression pattern of this gene in the cultivated rice variety in response to salt stress was similar with the previously known salt stress-tolerant gene, WRKY28. This indicated that these 4 Hsf genes might be among the conserved genes related to salt stress tolerance in the wild and cultivated rice. In summary, these results provide novel clues to the further functional studies of Hsf genes in rice for breeding programs.

Blocking of amino acid transporter OsAAP7 promoted tillering and yield by determining basic and neutral amino acids accumulation in rice

BackgroundAmino acids are not only the main form of N in rice, but also are vital for its growth and development. These processes are facilitated by amino acid transporters within the plant. Despite their significance, only a few AAP amino acid transporters have been reported.ResultsIn this study, we observed that there were differences in the expression of amino acid transporter OsAAP7 among 521 wild cultivated rice varieties, and it directly negatively correlated with tillering and grain yield per plant. We revealed that OsAAP7 protein was localized to the endoplasmic reticulum and had absorption and transport affinity for amino acids such as phenylalanine (Phe), lysine (Lys), leucine (Leu), and arginine (Arg) using subcellular localization, yeast substrate testing, fluorescent amino acid uptake, and amino acid content determination. Further hydroponic studies showed that exogenous application of amino acids Phe, Lys and Arg inhibited the growth of axillary buds in the overexpression lines, and promoted the elongation of axillary buds in the mutant lines. Finally, RNA-seq analysis showed that the expression patterns of genes related to nitrogen, auxin and cytokinin pathways were changed in axillary buds of OsAAP7 transgenic plants.ConclusionsThis study revealed the gene function of OsAAP7, and found that blocking of amino acid transporter OsAAP7 with CRISPR/Cas9 technology promoted tillering and yield by determining basic and neutral amino acids accumulation in rice.

Appropriate Stubble Height Can Effectively Improve the Rice Quality of Ratoon Rice.

Ratoon rice, the cultivation of a second crop from the stubble after the main harvest, is recognized as an eco-friendly and resource-saving method for rice production. Here, a field experiment was carried out in the Yangtze River region to investigate the impact of varying stubble heights on the grain quality of ratoon rice, as well as to compare the grain quality between the main and ratoon season. This study, which focused on 12 commonly cultivated rice varieties, conducted a comprehensive analysis assessing milling characteristics, appearance, and cooking quality. The results show that ratoon rice crops exhibited a higher milled rice rate and head rice rate compared to the main rice crops. Conversely, chalky rice percentage, chalkiness degree, and amylose content were lower in ratoon rice crops. Principal component analysis grouped eight relevant quality indicators of rice quality which were concentrated into three categories, with amylose content identified as the key indicator of rice quality for distinguishing between different stubble heights. Random forest results reveal a robust and significant correlation between appearance quality index and amylose content. Subordinate function analysis indicated that a stubble height of 30 cm resulted in optimal rice quality, with Lingliangyou 211 exhibiting the highest quality and Xiangzao Xian 32 the lowest. Overall, our study suggests that ratoon rice crops generally outperform main rice crops in terms of quality, with the optimal measurement at a stubble height of 30 cm. This study holds substantial importance for selecting appropriate stubble heights for ratoon rice crops and enhancing overall rice quality.

Pangenome-Wide Association Study and Transcriptome Analysis Reveal a Novel QTL and Candidate Genes Controlling both Panicle and Leaf Blast Resistance in Rice

Cultivating rice varieties with robust blast resistance is the most effective and economical way to manage the rice blast disease. However, rice blast disease comprises leaf and panicle blast, which are different in terms of resistance mechanisms. While many blast resistant rice cultivars were bred using genes conferring resistance to only leaf or panicle blast, mining durable and effective quantitative trait loci (QTLs) for both panicle and leaf blast resistance is of paramount importance. In this study, we conducted a pangenome-wide association study (panGWAS) on 9 blast resistance related phenotypes using 414 international diverse rice accessions from an international rice panel. This approach led to the identification of 74 QTLs associated with rice blast resistance. One notable locus, qPBR1, validated in a F4:5 population and fine-mapped in a Heterogeneous Inbred Family (HIF), exhibited broad-spectrum, major and durable blast resistance throughout the growth period. Furthermore, we performed transcriptomic analysis of 3 resistant and 3 sensitive accessions at different time points after infection, revealing 3,311 differentially expressed genes (DEGs) potentially involved in blast resistance. Integration of the above results identified 6 candidate genes within the qPBR1 locus, with no significant negative effect on yield. The results of this study provide valuable germplasm resources, QTLs, blast response genes and candidate functional genes for developing rice varieties with enduring and broad-spectrum blast resistance. The qPBR1, in particular, holds significant potential for breeding new rice varieties with comprehensive and durable resistance throughout their growth period.

Transcriptomic analysis of salt-tolerant and sensitive high-yield japonica rice (Oryza sativa L.) reveals complicated salt-tolerant mechanisms.

Developing and cultivating rice varieties is a potent strategy for reclaiming salinity-affected soils for rice production. Nevertheless, the molecular mechanisms conferring salt tolerance, especially in conventional high-yield japonica rice varieties, remain obscure. In this study, Zhendao 23309 (ZD23309) exhibited significantly less grain yield reduction under a salt stress gradient than the control variety Wuyunjing 30 (WYJ30). High positive correlations between grain yield and dry matter accumulation at the jointing, heading and maturity stages indicated that early salt tolerance performance is a crucial hallmark for yield formation. After a mild salt stress (85 mM NaCl) of young seedlings, RNA sequencing (RNA-seq) of shoot and root separately identified a total of 1952 and 3647 differentially expressed genes (DEGs) in ZD23309, and 2114 and 2711 DEGs in WYJ30, respectively. Gene ontology (GO) analysis revealed numerous DEGs in ZD23309 that play pivotal roles in strengthening salt tolerance, encompassing the response to stimulus (GO:0050896) in shoots and nucleoside binding (GO:0001882) in roots. Additionally, distinct expression patterns were observed in a fraction of genes in the two rice varieties under salt stress, corroborating the efficacy of previously reported salt tolerance genes. Our research not only offers fresh insights into the differences in salt stress tolerance among conventional high-yield rice varieties but also unveils the intricate nature of salt tolerance mechanisms. These findings lay a solid groundwork for deciphering the mechanisms underlying salt tolerance.

Transcription factor encoding gene OsC1 regulates leaf sheath color through anthocyanidin metabolism in Oryza rufipogon and Oryza sativa

Carbohydrates, proteins, lipids, minerals and vitamins are nutrient substances commonly seen in rice grains, but anthocyanidin, with benefit for plant growth and animal health, exists mainly in the common wild rice but hardly in the cultivated rice. To screen the rice germplasm with high intensity of anthocyanidins and identify the variations, we used metabolomics technique and detected significant different accumulation of anthocyanidins in common wild rice (Oryza rufipogon, with purple leaf sheath) and cultivated rice (Oryza sativa, with green leaf sheath). In this study, we identified and characterized a well-known MYB transcription factor, OsC1, through phenotypic (leaf sheath color) and metabolic (metabolite profiling) genome-wide association studies (pGWAS and mGWAS) in 160 common wild rice (O. rufipogon) and 151 cultivated (O. sativa) rice varieties. Transgenic experiments demonstrated that biosynthesis and accumulation of cyanidin-3-Galc, cyanidin 3-O-rutinoside and cyanidin O-syringic acid, as well as purple pigmentation in leaf sheath were regulated by OsC1. A total of 25 sequence variations of OsC1 constructed 16 functional haplotypes (higher accumulation of the three anthocyanidin types within purple leaf sheath) and 9 non-functional haplotypes (less accumulation of anthocyanidins within green leaf sheath). Three haplotypes of OsC1 were newly identified in our germplasm, which have potential values in functional genomics and molecular breeding of rice. Gene-to-metabolite analysis by mGWAS and pGWAS provides a useful and efficient tool for functional gene identification and omics-based crop genetic improvement.

Potential Momilactones in Rice Stress Tolerance and Health Advantages

The aim of this review was to provide an updated outlook on the relevance of momilactones in rice during the 50 years since their discovery. Momilactones A (MA) and B (MB) were initially extracted from rice husks in 1973 and have since been identified in various parts of the rice plant including leaves, bran, straw, roots, and root exudates. The biosynthesis of these compounds in rice initiates from geranylgeranyl diphosphate (GGDP) and progresses through several cyclization stages. The genes governing the synthesis of MA and MB are located on chromosome 4 within the rice genome. Concentrations of these compounds vary across different parts of the rice plant, ranging from 2 to 157 μg/g. Notably, Japonica rice varieties tend to have higher levels of MA and MB (157 and 83 μg/g, respectively) compared to Indica varieties (20.7 and 4.9 μg/g, respectively). There is a direct correlation between the levels of MA and MB and the increase in antioxidant activity, protein, and amylose content in rice grains. The production of these compounds is enhanced under environmental stresses such as drought, salinity, chilling, and UV exposure, indicating their potential role in rice’s tolerance to these conditions. MA and MB also demonstrate allelopathic, antibacterial, and antifungal properties, potentially improving the resilience of rice plants against biotic stressors. Although their antioxidant activity is modest, they effectively inhibit leukemia cells at a concentration of 5 µM. They also show promise in diabetes management by inhibiting enzymes like α-amylase (with IC50 values of 132.56 and 129.02 mg/mL, respectively) and α-glucosidase (with IC50 values of 991.95 and 612.03 mg/mL, respectively). The therapeutic qualities of MA and MB suggest that cultivating rice varieties with higher concentrations of these compounds, along with developing their derivatives, could benefit the pharmaceutical industry and enhance treatments for chronic diseases. Consequently, breeding rice cultivars with increased momilactone levels could offer substantial advantages to rice farmers.

Gene Flow Between the Wild Rice Species (Oryza longistaminata) and Two Varieties of Cultivated Rice (Oryza sativa) in Kilombero District, Tanzania

The direction and rate of gene flow between the perennial wild rice species, O. longistaminata and cultivated rice, O. sativa was investigated using nine Microsatellite (SSR) markers. The study involved characterization of parental lines of two cultivated rice varieties and O. longistaminata and their F1 progenies. Presence of crop-specific alleles in the wild species or vice-versa was used as an indicator of occurrence of gene flow between the two species. The study revealed that gene flow between O. longistaminata and each of the two varieties of O. sativa occurs naturally. The direction of gene flow was mainly from the cultivated to wild species. The rate (frequency) of gene flow was higher from cultivated (O. sativa) to wild rice (O. longistaminata) than from O. longistaminata to O. sativa and varied with cultivated rice variety. Higher rate of gene flow from cultivated to wild species could be due to floral structure and out-crossing nature of the wild species (O. longistaminata). Gene flow between O. longistaminata and O. sativa is likely to change genetic integrity of natural populations of the two species in areas where they occur sympatrically. However, isolation by distance can help to control gene flow between these species.

Defense Responses of Different Rice Varieties Affect Growth Performance and Food Utilization of Cnaphalocrocis medinalis Larvae

Rice leaf folder, Cnaphalocrocis medinalis (Guenée), is one of the most serious pests on rice. At present, chemical control is the main method for controlling this pest. However, the indiscriminate use of chemical insecticides has non-target effects and may cause environmental pollution. Besides, leaf curling behavior by C. medinalis may indirectly reduce the efficacy of chemical spray. Therefore, it is crucial to cultivate efficient rice varieties resistant to this pest. Previous studies have found that three different rice varieties, Zhongzao39 (ZZ39), Xiushui134 (XS134), and Yongyou1540 (YY1540), had varying degrees of infestation by C. medinalis. However, it is currently unclear whether the reason for this difference is related to the difference in defense ability of the three rice varieties against the infestation of C. medinalis. To explore this issue, the current study investigated the effects of three rice varieties on the growth performance and food utilization capability of the 4th instar C. medinalis. Further, it elucidated the differences in defense responses among different rice varieties based on the differences in leaf physiological and biochemical indicators and their impact on population occurrence. The results showed that the larval survival rate was the lowest, and the development period was significantly prolonged after feeding on YY1540. This was not related to the differences in leaf wax, pigments, and nutritional components among the three rice varieties nor to the feeding preferences of the larvae. The rate of superoxide anion production, hydrogen peroxide content, and the activity of three protective enzymes were negatively correlated with larval survival rate, and they all showed the highest in YY1540 leaves. Compared to other tested varieties, although the larvae feeding on YY1540 had higher conversion efficiency of ingested food and lower relative consumption rate, their relative growth was faster, indicating stronger food utilization capability. However, they had a lower accumulation of protein. This suggests that different rice varieties had different levels of oxidative stress after infestation by C. medinalis. The defense response of YY1540 was more intense, which was not conducive to the development of the larvae population. These results will provide new insights into the interaction mechanism between different rice varieties and C. medinalis and provide a theoretical basis for cultivating rice varieties resistant to this pest.

Genome-Wide Association Analysis Unravels New Quantitative Trait Loci (QTLs) for Eight Lodging Resistance Constituent Traits in Rice (Oryza sativa L.).

Lodging poses a significant challenge to rice yield, prompting the need to identify elite alleles for lodging resistance traits to improve cultivated rice varieties. In this study, a natural population of 518 rice accessions was examined to identify elite alleles associated with plant height (PH), stem diameter (SD), stem anti-thrust (AT/S), and various internode lengths (first (FirINL), second (SecINL), third (ThirINL), fourth (ForINL), and fifth (FifINL) internode lengths). A total of 262 SSR markers linked to these traits were uncovered through association mapping in two environmental conditions. Phenotypic evaluations revealed striking differences among cultivars, and genetic diversity assessments showed polymorphisms across the accessions. Favorable alleles were identified for PH, SD, AT/S, and one to five internode lengths, with specific alleles displaying considerable effects. Noteworthy alleles include RM6811-160 bp on chromosome 6 (which reduces PH) and RM161-145 bp on chromosome 5 (which increases SD). The study identified a total of 42 novel QTLs. Specifically, seven QTLs were identified for PH, four for SD, five for AT/S, five for FirINL, six for SecINL, five for ThirINL, six for ForINL, and four for FifINL. QTLs qAT/S-2, qPH2.1, qForINL2.1, and qFifINL exhibited the most significant phenotypic variance (PVE) of 3.99% for the stem lodging trait. AT/S, PH, ForINL, and FifINL had additive effects of 5.31 kPa, 5.42 cm, 4.27 cm, and 4.27 cm, respectively, offering insights into eight distinct cross-combinations for enhancing each trait. This research suggests the potential for crossbreeding superior parents based on stacked alleles, promising improved rice cultivars with enhanced lodging resistance to meet market demands.

Nutritional and Medicinal Value of Red Rice

Background: Various varieties of rice (Oryza sativa) have been exploited for a variety of purposes since ancient times, with the integration into foods, cosmetics, and pharmaceutical products. A huge diversity is seen in the cultivated rice variety based on regions, area, and climatic conditions responsible for variation in chemical composition leading to enriched supplements beneficial for health conditions. Among the varieties available, red rice extract is now increasingly recognized for its antioxidant, anti-inflammatory activity, anti-diabetic, anti-hyperlipidemic activity, and bone formation. Objective: There is a need to validate the nutritional and supplement values through appropriate analytical and pharmacological studies and create awareness for the end users regarding the value of red rice. Results: In the present article attempt is done to reviewthe variety of red rice based on geographical origin, and the impact on nutritional and medicinal value. Further elaborating the extraction techniques which can help optimize the extraction efficiency of polyphenols known for their antioxidant properties. Polyphenolic phytoconstituents belonging to phenolic acids, and flavonoids include, flavonols, flavones, flavanols, flavanones, and isoflavones, to name a few. Anthocyanins, and proanthocyanidins make the pigment part of the outer layer and bran of the rice and contain the monomers of catechin, epicatechin, gallocatechin, and epigallocatechin units. The quantification of the phytoconstituents using chromatographical methods can help in evaluation of the red rice for its quality and design formulation with desired efficacy. Conclusion: With the vast varieties of red rice available, quantification of important bio-actives can help in maintaining quality of final product. Various targeted pharmacological actions reported include anti-inflammatory, antihyperlipidemic, antidiabetic, anticancer and antioxidant produced by the rice, mainly by virtue of the polyphenolic content, contribute in achieving a value to rice as nourishment and a safe therapeutic product which can be consumed as a nutraceutical or pharmaceutical ingredient.

Assessing clethodim spot spraying applications for control of problematic weedy rice and other grasses in California rice fields

AbstractSpot spraying applications offer the opportunity to target specific weeds in a field, while simultaneously reducing herbicide usage and increasing the long‐term efficacy of chemical control options. The study is focused on controlling California weedy rice accessions (Oryza spp.) and problematic grass weeds with a spot spray application of clethodim in a flooded rice system. The efficacy of incorporating nonionic surfactant to clethodim applications was also assessed. Dose‐response experiments were carried out in a greenhouse on five weedy rice accessions, common grass rice weeds, and cultivated rice varieties L207, M105, M206, M209, M211, and S102 to determine the dose needed to affect these populations. Clethodim was applied in a field setting to assess spot spraying efficacy, the possibility of herbicide dispersion in the water, and crop injury. Clethodim successfully controlled weedy rice and grasses in the greenhouse. The effective rates to control 90% of the five test populations (ED90) were between 51 and 74 g ai ha−1 clethodim for weedy rice accessions. Adding nonionic surfactant to clethodim increased its efficacy by 1.6‐ to 1.9‐fold. Cultivated rice varieties did not exhibit any tolerance to clethodim, however, spot spraying applications at 150 g ai ha−1 clethodim did not cause any dispersion in the field. Clethodim spot spray application was effective both at the three‐ to four‐leaf growth stage and tillering growth stage for weedy rice.

Endophytic bacterial communities in wild rice (Oryza officinalis) and their plant growth-promoting effects on perennial rice.

Endophytic bacterial microbiomes of plants contribute to the physiological health of the host and its adaptive evolution and stress tolerance. Wild rice possesses enriched endophytic bacteria diversity, which is a potential resource for sustainable agriculture. Oryza officinalis is a unique perennial wild rice species in China with rich genetic resources. However, endophytic bacterial communities of this species and their plant growth-promoting (PGP) traits remain largely unknown. In this study, endophytic bacteria in the root, stem, and leaf tissues of O. officinalis were characterized using 16S rRNA gene Illumina sequencing. Culturable bacterial endophytes were also isolated from O. officinalis tissues and characterized for their PGP traits. The microbiome analysis showed a more complex structure and powerful function of the endophytic bacterial community in roots compared with those in other tissue compartments. Each compartment had its specific endophytic bacterial biomarkers, including Desulfomonile and Ruminiclostridium for roots; Lactobacillus, Acinetobacter, Cutibacterium and Dechloromonas for stems; and Stenotrophomonas, Chryseobacterium, Achromobacter and Methylobacterium for leaves. A total of 96 endophytic bacterial strains with PGP traits of phosphate solubilization, potassium release, nitrogen fixation, 1-aminocyclopropane-1-carboxylate (ACC) deaminase secretion, and siderophore or indole-3-acetic acid (IAA) production were isolated from O. officinalis. Among them, 11 strains identified as Enterobacter mori, E. ludwigii, E. cloacae, Bacillus amyloliquefaciens, B. siamensis, Pseudomonas rhodesiae and Kosakonia oryzae were selected for inoculation of perennial rice based on their IAA production traits. These strains showed promising PGP effects on perennial rice seedlings. They promoted plants to form a strong root system, stimulate biomass accumulation, and increase chlorophyll content and nitrogen uptake, which could fulfil the ecologically sustainable cultivation model of perennial rice. These results provide insights into the bacterial endosphere of O. officinalis and its application potential in perennial rice. There is the prospect of mining beneficial endophytic bacteria from wild rice species, which could rewild the microbiome of cultivated rice varieties and promote their growth.

A Rapid and Accurate Quantitative Analysis of Cellulose in the Rice Bran Layer Based on Near-Infrared Spectroscopy.

Cultivating rice varieties with lower cellulose content in the bran layer has the potential to enhance both the nutritional value and texture of brown rice. This study aims to establish a rapid and accurate method to quantify cellulose content in the bran layer utilizing near-infrared spectroscopy (NIRS), thereby providing a technical foundation for the selection, screening, and breeding of rice germplasm cultivars characterized by a low cellulose content in the bran layer. To ensure the accuracy of the NIR spectroscopic analysis, the potassium dichromate oxidation (PDO) method was improved and then used as a reference method. Using 141 samples of rice bran layer (rice bran without germ), near-infrared diffuse reflectance (NIRdr) spectra, near-infrared diffuse transmittance (NIRdt) spectra, and fusion spectra of NIRdr and NIRdt were used to establish cellulose quantitative analysis models, followed by a comparative evaluation of these models' predictive performance. Results indicate that the optimized PDO method demonstrates superior precision compared to the original PDO method. Upon examining the established models, their predictive capabilities were ranked in the following order: the fusion model outperforms the NIRdt model, which in turn surpasses the NIRdr model. Of all the fusion models developed, the model exhibiting the highest predictive accuracy utilized fusion spectra (NIRdr-NIRdt (1st der)) derived from preprocessed (first derivative) diffuse reflectance and transmittance spectra. This model achieved an external predictive R2p of 0.903 and an RMSEP of 0.213%. Using this specific model, the rice mutant O2 was successfully identified, which displayed a cellulose content in the bran layer of 3.28%, representing a 0.86% decrease compared to the wild type (W7). The utilization of NIRS enables quantitative analysis of the cellulose content within the rice bran layer, thereby providing essential technical support for the selection of rice varieties characterized by lower cellulose content in the bran layer.