Rice Grain Research Articles

Investigation of rice debranning mechanism based on tribological behaviour between rice grains

Frictional debranning between rice grains is a fragile and energy-consuming process. Understanding the mechanism of this frictional debranning is the key to achieving moderate debranning, yet the mechanisms involved remain poorly understood. In this work, the mechanism of rice grain debranning was investigated through rice milling experiments, SEM analysis of the rice surface, and rice wear experiments. The results showed that the bran layer of rice grains exhibited different removal patterns at different milling pressures. During frictional debranning between rice grains, adhesive wear and bulk stripping of the bran layer occurred. The bran layer of the rice grain initially experiences primary damage due to adhesive wear, followed by bulk stripping at the edges of the existing damage. Pre-milling can effectively improve the debranning efficiency of rice grains. These findings should provide a theoretical reference for the design of grain milling equipment and the process improvement of grain moderate milling.

Deep-freezing as a novel disinfestation strategy to rice weevil (Sitophilus oryzae Linnaeus) in packaged milled rice grains: Factors and lethal behaviors

Rice weevil (Sitophilus oryzae Linnaeus) is a major insect pest of milled rice grains, which poses a great threat to food security. In this study, the feasibility of three deep-freezing regimes (-20, -80, and -196 oC) to disinfest packaged milled rice grains was explored. It was found that the disinfestation efficiency increased with the decrease in freezing temperature. For naked insects, complete mortality was achieved by the regimes at -20, -80, and -196 oC with the exposure time of 8 min, 2 min, and as short as 1 s, respectively. For insects in packaged rice grains (5 insects/500 g rice; package size: 8 cm × 5 cm × 13 cm), the corresponding exposure time was determined as 100, 40, and 4 min, respectively. Upon the increase in insect population density and package size, the longer exposure time was required for complete mortality. When the regime at -196 oC (1.5 min) was used as a pretreatment at -20 oC (60 min), the highest combination index (2.12) was obtained for the complete mortality. In one word, deep-freezing was successfully developed as a novel method to disinfest adult rice weevil in packaged milled rice grains.

Dispersal ability of the predatory mites Blattisocius tarsalis and Cheyletus malaccensis in grain piles and storage facilities

Predatory mites can be released into storage facilities to control various stored product pests. However, their ability to disperse within grain piles and structures (warehouses and processing facilities) has not been well assessed. This study aimed to evaluate two predatory mites, Blattisocius tarsalis and Cheyletus malaccensis, as biological control agents by examining their dispersal abilities in piles of rice grains and storage facilities. The mites were evaluated for their capacity to navigate vertically through polyvinyl chloride (PVC) tubes filled with paddy rice at depths of 40 and 100 cm to determine if they could reach the eggs of various lepidopteran pests at the bottom. Additionally, their dispersal ability over varying time intervals and their preferences concerning light intensity were assessed in 2-metre-long channels coated with rice flour residues. An integrated assessment of their vertical and horizontal dispersal capacities, along with the influence of light, was conducted in a controlled pilot storage room (4 × 3 × 3 m). Blattisocius tarsalis demonstrated impressive dispersal capabilities, reaching pest eggs at vertical depths of 40 and 100 cm through rice and dispersing 2 m horizontally in just 4 h. This proficiency extended to pilot storage room conditions, where it successfully navigated all distances, both horizontally and vertically, showing a preference for navigating away from the light. Cheyletus malaccensis proved to be an effective predator at close range to pest eggs but demonstrated limited dispersal capabilities in complex setups. This study underlines the suitability of B. tarsalis as a biological control agent capable of dispersing in various environments. Conversely, the utility of C. malaccensis may be more specialised and effective within a narrow movement range. These findings highlight the importance of understanding mite dispersal behaviours for optimising pest management strategies and contributing to the more sustainable and effective storage of rice grains.

Occurrence of per- and polyfluoroalkyl substances in wheat, maize, rice, and soybean from chinese major grain producing regions.

Dietary exposure to per- and polyfluoroalkyl substances (PFAS) has been a concern for many years. Previous studies demonstrated that foods such as meat, milk, fish, vegetables, and tuber crops could be potential sources of human exposure to PFAS. However, research on PFAS contamination in grains remains limited. Therefore, this study conducted a comprehensive investigation of PFAS contamination in raw grains from major grain-producing regions in China. Among all grain species, soybeans exhibited the highest Σ16PFAS level (1.01ng/g dw), followed by rice (0.570ng/g dw), wheat (0.542ng/g dw), and maize (0.245ng/g dw). Short-chain perfluoroalkyl carboxylates (PFCAs) displayed higher detection frequencies compared to their long-chain homologues and perfluoroalkyl sulfonates (PFSAs). Perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) were dominant in wheat, maize, and soybean samples, while sodium p-perfluorous nonenoxybenzenesulfonate (OBS) was predominant in rice. OBS contributed approximately 70% to Σ16PFAS concentrations in rice. The concentration difference of OBS was not significant between indica rice and japonica rice, however, a disparity was observed between early indica rice and mid-late indica rice, suggesting that the growing period potentially affects OBS level in rice grains. Compared to other regions, east China displayed relatively higher PFAS concentrations in grain samples. This finding is consistent with previous studies and may be attributed to the intensive industrial and human activities. The estimated daily intake (EDI) of Σ16PFAS in grains from this study ranged from 0.0829 to 3.32ng/kg bw/day. The dietary health risks associated with PFOA in wheat and OBS in rice warrant further attention.

Efficacy of Titanium Dioxide Nanoparticles Using Juniperus phoenicea in Controlling Rice Weevil (Sitophilus oryzae) and Its Effect on the Microbial Contents and Nutritive Value of Grains

The rice weevil, Sitophilus oryzae is a primary pest attack many kinds of crops. It causes a lot of loss and reduces the economic values of products. The study investigated to determine the insecticidal effect of titanium dioxide nanoparticles using Juniperus phoenicea (TiO2 NPs) against the insect, and the nutritional and antimicrobial value of rice grains after treatment by TiO2 NPs was estimated. Adult was the target of bioassay of the biocomponent. Four concentrations were prepared as 30, 50, 80 and 100%. Some biochemical components were evaluated as response indicators of insect. Obtained data demonstrated significant differences between the four concentrations, where the highest mortality was recorded after 120 h. On the adults (85%). Treatment with the titanium dioxide nanoparticles inhibited the activities of acetylcholine esterase and total soluble protein. While it increases the activity of catalase as antioxidant enzyme. Nutritional values increased with increasing the proportion of TiO2 NPs, except for the decrease in protein. No colonization of coliform bacteria and fungi cell was recorded in 80% of TiO2 NPs, aerobic bacteria were reduced to a lower number 12 CFU/g 103 at 100%. Biosynthesized titanium dioxide nanoparticles with J. phoenicea extract is promising bio-insecticide and antimicrobial in integrated pest management control, preserving the nutritional value of grains during storage.

Foliar application of chitosan and brassinosteroids on glutinous rice (‘RD6’): Alteration in growth, agronomic trait, antioxidant capacity, elemental composition and aroma compound, 2-acetyl-1-pyrroline (2AP) in rice grain

Foliar application of chitosan and brassinosteroids on glutinous rice (‘RD6’): Alteration in growth, agronomic trait, antioxidant capacity, elemental composition and aroma compound, 2-acetyl-1-pyrroline (2AP) in rice grain

Key active mercury methylating microorganisms and their synergistic effects on methylmercury production in paddy soils

Rice contamination with neurotoxic methylmercury (MeHg) from paddy soils is an escalating global concern. Identifying the microorganisms responsible for mercury (Hg) methylation in these soils is essential for controlling Hg contamination in the food chain and mitigating health impacts. Current research often focuses on total Hg-methylating microorganisms, overlooking the contributions of active ones, which can lead to either overestimating or neglecting the specific roles of microorganisms in Hg methylation within paddy soils. In this study, active Hg-methylating microorganisms in paddy soils were identified using a combination of DNA-SIP, Hg isotope labelling, and Hg methylation gene sequencing techniques. Our findings revealed that Geobacter and Anaerolinea are pivotal active Hg-methylating microorganisms across a contamination gradient in paddy soils. Transcriptomic analysis of soils from major rice-producing provinces in China confirmed the widespread and synergistic involvement of these microorganisms. Microbial incubation further validated their interaction significantly enhances Hg methylation, with Me198Hg concentrations increasing 2.8-fold compared to Geobacter alone and 5.2-fold compared to Anaerolinea alone. These findings enhance our understanding of microbial Hg methylation in paddy soils, providing critical insights for accurately predicting soil MeHg load, rice grain MeHg contamination, and human MeHg exposure risks.

Life cycle assessment of ethanol production from broken wheat and rice grains

Life cycle assessment of ethanol production from broken wheat and rice grains

Evaluating rice lipid content, yield, and quality in response to nitrogen application rate and planting density

To investigate the effects of nitrogen (N) application rate and planting density (D) on the contents of lipid and free fatty acid, fatty acid composition, yield and quality of rice grain, a field experiment was conducted using Koshihikari (japonica) as experimental material from 2021 to 2022 with three N levels (90, 150 and 210 kg ha-1, denoted as N1, N2 and N3, respectively) and three transplanting densities (19.0 × 104, 26.7 × 104 and 40.0 × 104 plants ha-1, denoted as D1, D2 and D3, respectively). The results showed that N application rate and planting density had highly significant impacts only on the contents of free fatty acid and saturated fatty acid, respectively. Increased N and planting density enhanced the contents of lipid (29.41 mg g-1) and free fatty acid (21.47%). The highest values were obtained under N3D3 increasing by 7.02% and 3.23 percentage points, respectively, compared to other treatments. No significant differences in lipid content were found among treatments, whereas free fatty acid exhibited significant differences. The unsaturated fatty acid content increased with increasing N but first decreased and then increased with increasing planting density, while saturated fatty acid content showed the opposite trend. Appropriate N level and planting density improved the relative chlorophyll content and net photosynthetic rate of rice flag leaves, as well as increased grain yield, effective panicle number and spikelete number per panicle, but decreased the seed setting rate. Under N2D2, the relative chlorophyll content and net photosynthetic rate remained relatively high throughout the grain filling stage, resulting in the highest grain yield, with increases of 43.87-47.03% compared to other treatments. A moderate N level improved the milling quality of rice, while increased planting density reduced it. However, both increased N and planting density reduced the appearance quality and cooking and eating quality of rice. Overall, the effects of increasing N application rate and planting density on enhancing rice lipid and free fatty acid contents were limited. A combination of 150 kg ha-1 N application rate and 26.7 × 104 plants ha-1 was recommended for achieving relatively higher yield, lipid content and better grain quality.

Quantitative trait locus mapping and OsFLOq12 identification for rice grain hardness: towards improved rice flour for wheat substitution.

Recent shifts in consumer dietary preferences have led to a significant decline in rice consumption in Korea, resulting in surplus rice production. To address this issue, rice flour has been proposed as a substitute for wheat flour. However, the physical, chemical and structural differences between rice and wheat, particularly in grain hardness, pose challenges in using rice flour as an alternative. Understanding the genetic factors that influence rice grain hardness is crucial for improving the milling process and producing high-quality rice flour suitable for wheat flour substitution. In this study, various grain traits, including length, width, thickness, length-to-width ratio and hardness, were measured in a population of brown and milled rice. Quantitative trait locus (QTL) analysis revealed a significant association between grain hardness and thickness, with QTLs for grain hardness mapped on chromosomes 1 and 12 for brown and milled rice, respectively. A total of 20 candidate genes related to grain hardness were identified through QTL analysis. Among them, OsFLOq12 (LOC_Os12g43550) was identified as a key gene influencing grain hardness, which encodes a Ras small GTPase. Phenotypic analysis showed differences in endosperm appearance and particle size between lines with low and high grain hardness. The genetic analysis of OsFLOq12 revealed a single nucleotide polymorphism associated with grain hardness. This study provides valuable insights into the genetic background of grain hardness, offering a foundation for breeding rice varieties optimized for flour production as a viable substitute for wheat flour. © 2024 Society of Chemical Industry.

Maximizing Productivity and Profitability of Rice through Crop Establishment Methods and Weed Management Practices in Winter Rice-Garden Pea Relay Cropping System

A field experiment was conducted at the farmer’s field at Pirakata Brahmin Gaon under the jurisdiction of Krishi Vigyan Kendra, Jorhat to study resource conservation through crop establishment methods and weed management practices in winter rice (Oryza sativa. L.) - garden pea (Pisum sativum var. hortense) relay cropping system during 2019-20 & 2020-21. The treatment consisted of four crop establishment methods of winter rice (T) viz., T1: WDSR (Broadcasting), T2: WDSR (Modified Drum Seeder with furrow opener), T3: PTR (Farmers’ Practice), T4: PTR (Mechanized Transplanting by paddy transplanter) where WDSR: Wet Direct Seeded Rice, PTR: Puddled Transplanted Rice along with three weed management practices of rice (W) viz., W0: Weedy check, W1: Pretilachlor 0.75 kg/ha as pre-emergence fb bispyribac-sodium 0.025 kg/ha (20 DAS/DAT) as post-emergence, W2: Pretilachlor 0.75 kg/ha as pre-emergence fb manual weeding (30 DAS/DAT). The experiment was laid out in a factorial randomized block design with three replications. The soil of the experimental site was sandy clay loam in texture, medium acidic in reaction, medium in organic carbon and available N and low in available P2O5 and K2O. The study revealed that the establishment method that T2, T3 and T4 had higher growth and yield parameters of the crop as compared to T1: WDSR (B) which resulted in higher grain and straw yield of winter rice as well as uptake of nutrients. The highest grain yield of 49.79 and 50.13 q/ha of winter rice was recorded under T4: PTR (MTR) followed by 46.62 and 47.8 q/ha in T2: WDSR (Drum seeder) during 2019 and 2020, respectively. The percent increase in grain yield of winter rice in W1 and W2 as compared to W0 (control) was 82.97, 84.52 in 2019 and 81.62, 81.58, respectively in 2020. The treatment combination T4W2 recorded the highest grain and straw yield of winter rice which was statistically at par with T4W1, T2W1 and T2W2. The higher B:C of 2.27 and 2.14 was recorded in T2W1 with higher gross return and net return followed by T2W2 (2.18 and 2.08 during 2019 and 2020, respectively).

Genetic Dissection of Milled Rice Grain Shape by Using a Recombinant Inbred Line Population and Validation of qMLWR11.1 and qMLWR11.2

Grain shape in rice (Oryza sativa L.) is a complex trait governed by multiple quantitative trait loci (QTLs). To dissect the genetic basis of rice shape, QTL analysis was conducted for milled rice grain width (MGW), milled rice grain length (MGL), and milled rice length-to-width ratio (MLWR) using a recombinant inbred line (RIL) population of F10 and F11 generations derived from a cross between Yuexiangzhan and Shengbasimiao. A high-density genetic map consisting of 2412 bins was constructed by sequencing 184 RILs, spanning a total length of 2376.46 cM. A total of 19 QTLs related to MGL, MGW, and MLWR were detected under two environments. The range of phenotypic variation attributed to individual QTL ranged from 1.67% to 32.08%. Among those, a novel locus for MGL, MGW and MLWR, designated as qMLWR3.2, was pinpointed within a specific ~0.96-Mb region. Two novel loci for MGW and MLWR, qMLWR11.1 and qMLWR11.2, were verified within ~1.22-Mb and ~0.52-Mb regions using three RIL-developed populations, respectively. These findings lay the foundation for further map-based cloning and molecular design breeding in rice.

Palmer amaranth (Amaranthus palmeri) Control in Furrow-Irrigated Rice with Fluridone

Abstract Herbicide-resistant Palmer amaranth is creating additional challenges for producers choosing to adopt a furrow-irrigated rice production system due to the absence of a sustained flood, enabling extended weed emergence. Fluridone has been shown to control Palmer amaranth effectively in cotton production systems and was recently registered for use in rice. Experiments were initiated in 2022 and 2023 to evaluate 1) Palmer amaranth control and rice tolerance to preemergence- and postemergence-applied fluridone at a 0.5x (84 g ai ha-1) and 1x rate (168 g ai ha-1) on a silt loam soil and 2) the effect of various herbicide programs containing fluridone on Palmer amaranth biomass, seed production, and rough rice grain yield. Preemergence applications of fluridone at a 1x rate in combination with clomazone resulted in 84% control of Palmer amaranth 21 d after treatment (DAT). Fluridone, in combination with clomazone preemergence, caused up to 36% rice injury 21 DAT; however, early season injury did not negatively affect rice yields. Palmer amaranth biomass and fecundity were reduced with herbicide programs that included fluridone plus florpyrauxifen-benzyl, and, in some instances, there was no Palmer amaranth biomass or seed production following multiple applications of both herbicides. Fluridone- and florpyrauxifen-benzyl-based herbicide programs achieved effective control of Palmer amaranth when applied timely, but injury to hybrid rice is enhanced with preemergence applications of fluridone that are not permitted with the current label.

Nutrient Uptake Patterns and Soil Fertility Assessment in Diverse Crop Rotations under Irrigated Dry Conditions in Telangana, India

An experiment was conducted during the 2023-24 kharif and rabi seasons at the College Farm, AICRP on the IFS unit, PJTSAU, Hyderabad. To develop efficient cropping systems for the Telangana region, it is essential to evaluate them based on productivity, nutrient uptake and economic viability. This study assessed various cropping sequences with regard to nutrient absorption and soil fertility status specific to Telangana and the findings were presented here. The rice-maize cropping system demonstrated higher nutrient uptake, resulting in a higher rice grain equivalent yield compared to Bt cotton under region-specific system. The Bt cotton + greengram (1:2) - sesame cropping system exhibited significantly higher nutrient uptake compared to the pigeonpea + foxtail millet (2:5) - sweet corn, making it more effective for sustaining long-term soil health. Among the crops cultivated for family nutritional security, the fingermillet – groundnut demonstrated significantly higher nutrient uptake compared to the pigeonpea + sorghum (2:3) - sesame. The nutrient uptake in the fodder bajra - lucerne system was higher than that in the fodder sorghum - fodder oats system when comparing the two fodder cropping systems. It has been observed that fodder systems required a greater amount of nutrients for their growth and development compared to other cropping systems.

Achieving synergistic benefits through integrated governance of cultivated cadmium contamination via multistakeholder collaboration.

Rice serves as a vital staple food, but its accumulation of cadmium (Cd) has sparked widespread concerns regarding food safety and ecosystem security. Here, we conducted a seven-year systematic field experiment in the Xiangjiang River Basin of China, where an integrated governance framework (IGF) was established to ensure rice safety. The IGF, tailored to geographical zoning and pollution gradation, includes targeted soil treatments, crop management strategies, and stakeholder engagement. The quality of both the soil and the crop was improved, with a reduction in soil Cd availability of 36%, and a decrease in Cd in rice grain of 57-78%. This framework not only addresses multiple challenges but also supports sustainable development goals (SDGs 2, 3, 6, 9) by fostering comprehensive synergies among science, policy, and local community participation. Our findings provide empirical guidance for safe rice production in Cd-contaminated areas and provide solid scientific-driven decision support globally.

Determine the Balance of Nitrogen, Potassium, and Silicon Fertilization for the Control of Rice Tungro Disease Using Response Surface Methodology

This study evaluates the efficacy of combined N, K, and Si treatments to find the balance of these three elements for tungro disease control and rice grain production. The study was conducted in a pot under a glasshouse. These elements were chosen as several findings have indicated the positive benefits of nitrogen (N), potassium (K), and silicon (Si) fertilization on plant development, yield, and biotic stress relief. The methods used were central composite design and response surface methodology. Complete and balanced nutrition has always been the first line of defense for plants due to the direct involvement of mineral elements in plant protection. The results showed that rice tungro disease could be controlled with 138:42:62:200 (N:P2O5:K2O:Si). A high rate of nitrogen is needed to reduce disease development. The results on N may explain that not all conditions of rice plants are at risk with high N rates. Adding Si fertilizer contributes to plant defense mechanisms and plays a role in yield formation. In contrast, the balance of fertilizer for maximizing grain yield per plant was found to be not dependent on nitrogen but needed either low K (62 kg K2O/ha) or high K (80 kg K2O/ha) but with moderate Si (150 kg Si/ha). Prioritizing tungro disease control and adopting the rate of N:K2O:Si (138:62:200), it was found that there was a yield reduction of an average of 7.7%.

Integrating Nitrogen, Water, and Other Management Practices to Improve Grain and Ratoon Forage Yields in Perennial Rice

Perennial rice has recently garnered global attention due to its potential to save on seeds and labor costs and its high production efficiency. The “mid-season rice–ratoon forage” mode is a new planting system that has emerged in recent years. However, detailed information is still lacking on the regenerative characteristics, grain and ratoon forage yields, and forage nutrient content of perennial rice under different planting densities, nitrogen (N) rates, stubble heights, and water management practices. Four experiments with perennial rice were conducted in Sichuan Province, Southwest China, from 2017 to 2022. The results show that the rice grain and ratoon forage yields were significantly affected by year, planting density, and N. The grain yield was 28.18% and 60.81% lower in 2018F and 2019F, respectively, than in 2017F; similarly, the ratoon forage yield was 29.01% and 52.74% lower in 2018S and 2019S, respectively, than in 2017S. The low grain yield was mainly associated with lower numbers of spikelets per panicle and panicles per m2, which resulted from a lower regrowth rate, and the low ratoon forage yield was mainly attributed to the lower regrowth rate. The rice grain and ratoon forage yields increased with an increase in the N rate and planting density. The ratoon forage was found to be rich in crude protein, crude fat, crude fiber, calcium, nitrogen, phosphorus, potassium, and other nutrients. Moreover, the content of these nutrients increased significantly with an increase in the N rate. The regrowth rate and maximum tillers showed trends of first increasing and then decreasing with an increase in the stubble height under dry and wet alternation irrigation during the winter season. When the relative soil moisture decreased to below 80% during the winter season, the regrowth rate and seedling development index could reach more than 99% and 84%, respectively. Our results suggest that integrating N, water, and other management practices (including the combination of a 150 kg ha−1 N rate, 18.0 hills per m2, 10–20 cm rice stubble height, and alternating dry and wet irrigation during the winter season) is a feasible approach for achieving high grain and ratoon forage yields in perennial rice systems.

Heavy metal contamination and potential health risks in upland rice-producing soils of rotational shifting cultivation in northern Thailand

Rotational shifting cultivation (RSC) is commonly practiced in northern Thailand for upland rice cultivation, primarily for household consumption. However, the potential health risks from heavy metal contamination in these soils have not been thoroughly explored. This study aimed to evaluate the contamination of six heavy metals (Arsenic (As), Mercury (Hg), Cadmium (Cd), Lead (Pb), Copper (Cu), and Chromium (Cr)) in upland rice across RSC fields with varying fallow periods and assess the associated health risks from rice consumption. Four RSC fields with 5, 6, 10, and 12-year fallow periods were examined. The RSC-6Y and RSC-12Y fields were used for upland rice cultivation in 2022, while the RSC-5Y and RSC-10Y fields were cultivated in 2023. The geo-accumulation index (Igeo) was calculated, and translocation factors (TF) were assessed for the transfer of heavy metals from soil to straw (TFStraw/Soil), straw to grain (TFGrain/Straw), and soil to grain (TFGrain/Soil). The results indicated that after burning vegetation in the RSC fields, the highest concentrations of Pb, Cr, and Hg were found in the ash. In RSC soils, Cu, Cr, As, Pb, and Hg levels were below reference standards, with Cd undetected. In rice grains, the order of concentration was Pb > Cu > Cr > As, with Hg and Cd undetected. Pb levels in rice grains exceeded the safety threshold. Igeo values indicated no contamination to moderate contamination across sites, with negative Igeo values for Cr and Cu, and zero values for Cd. The TF results showed limited transfer of As, Hg, and Cd from soil to rice plants (TFStraw/Soil < 0.1), but notable transfer for Pb, Cr, and Cu. Pb was readily transferred from soil to grain (TFGrain/Soil), posing a potential health risk. The study highlights potential non-carcinogenic and carcinogenic risks from heavy metal exposure, particularly Pb, and underscores the need for further research to determine contamination sources and mitigation strategies.

Growth substrate limitation enhances anaerobic arsenic methylation by Paraclostridium bifermentans strain EML.

Microbial arsenic methylation is established as a detoxification process under aerobic conditions (converting arsenite to monomethylated arsenate) but is proposed to be a microbial warfare strategy under anoxic conditions due to the toxicity of its main product, monomethylarsonous acid (MMAs(III)). Here we leveraged a paddy soil-derived anaerobic arsenic methylator, Paraclostridium bifermentans strain EML, to gain insights into this process. Strain EML was inoculated into a series of media involving systematic dilutions of Reinforced Clostridial Broth (RCB) with 25 µM arsenite to assess the impact of growth substrate concentration on arsenic methylation. Growth curves evidenced the sensitivity of strain EML to arsenite, and arsenic speciation analysis revealed the production of MMAs(III). Concentrations of MMAs(III) and arsenic methylation gene (arsM) transcription were found to be positively correlated with RCB dilution, suggesting that substrate limitation enhances arsM gene expression and associated anaerobic arsenic methylation. We propose that growth substrate competition among microorganisms may also contribute to an increase in anaerobic arsenic methylation. This hypothesis was further evaluated in an anaerobic co-culture system involving strain EML and either wild-type Escherichia coli K-12 MG1655 (WT) or E. coli expressing the MMAs(III)-resistance gene (arsP) (ArsP E. coli). We observed increased MMAs(III) production in the presence of E. coli than its absence and growth inhibition of WT E. coli to a greater extent than ArsP E. coli, presumably due to the MMAs(III) produced by strain EML. Collectively, our findings suggest an ecological role for anaerobic arsenic methylation, highlighting the significance of microbe-microbe competition and interaction in this process.IMPORTANCEMicrobial arsenic methylation is highly active in rice paddy fields under flooded conditions, leading to increased accumulation of methylated arsenic in rice grains. In contrast to the known detoxification process for aerobic arsenic methylation, the ecological role of anaerobic arsenic methylation remains elusive and is proposed to be an antibiotic-producing process involved in microbial warfare. In this study, we interrogated a rice paddy soil-derived anaerobic arsenic-methylating bacterium, Paraclostridium bifermentans strain EML, to explore the effect of growth substrate limitation on arsenic methylation in the context of the microbial warfare hypothesis. We provide direct evidence for the role of growth substrate competition in anaerobic arsenic methylation via anaerobic prey-predator co-culture experiments. Moreover, we demonstrate a feedback loop, in which a bacterium resistant to MMAs(III) enhances its production, presumably through enhanced expression of arsM resulting from substrate limitation. Our work uncovers the complex interactions between an anaerobic arsenic methylator and its potential competitors.

New Innovations in Seed Morphology, and Plant Physiology for Crop Protection

The seed is a mainly reproductive unit of the spermatophyta and links the subsequent generations. Other essential seed activities include survival in arid, cold, or other adverse conditions and dispersal. There is a lot of variety in the internal and external architecture of seeds. OsMKP1, a mitogen-activated protein kinase phosphatase, is encoded by GSN1. Rice glume cells proliferate when GSN1 expression is suppressed, producing larger but fewer rice grains. The GSN1 directly interacts with OsMAPK6 and dephosphorylates it, rendering it inactive. Thus, precise regulation of OsMAPK6 activity via reversible phosphorylation is essential for regulating the rice grain size. Some genes also negatively control the grain width and weight by inhibiting cell proliferation. The embryo, which is made up of cotyledons, hypocotyl, and radicle; the endosperm, which feeds the growing embryo; and the seed coat, which envelops the embryo and the endosperm, are the three main parts of plant seeds, each of which has unique biological functions and outcome. The growing seed can benefit from the ability to predict when a sugar burst would arrive through the phloem, since this would allow the seed to quickly adapt to its storage product synthesis. However, there are still certain obstacles that prevent the use against a variety of insect species. The adoption of various formulation procedures that improve dsRNA persistence and cellular absorption in insects is expected to overcome these issues, which are mostly related to the varying RNAi sensitivity of oral RNAi in insects. The CRISPR/Cas system has become the most popular being shown to be useful for editing the genome of plants, its uses in plants have grown significantly in comparison to other technologies.