A Multi-Target Regression Method to Predict Element Concentrations in Tomato Leaves Using Hyperspectral Imaging.

Recent years have seen the development of novel, rapid, and inexpensive techniques for collecting plant data to monitor the nutritional status of crops. These techniques include hyperspectral imaging, which has been widely used in combination with machine learning models to predict element concentrations in plants. When there are multiple elements, the machine learning models are trained with spectral features to predict individual element concentrations; this type of single-target prediction is known as single-target regression. Although this method can achieve reliable accuracy for some elements, there are others that remain less accurate. We aimed to improve the accuracy of element concentration predictions by using a multi-target regression method that sequentially augmented the original input features (hyperspectral imaging) by chaining the predicted element concentration values. To evaluate the multi-target method, the concentrations of 17 elements in tomato leaves were predicted and compared with the single-target regression results. We trained 5 machine learning models with hyperspectral data and predicted element concentration values and found a significant improvement in the prediction accuracy for 10 elements (Mg, P, S, Mn, Fe, Co, Cu, Sr, Mo, and Cd). Furthermore, our multi-target regression method outperformed single-target predictions by increasing the coefficient of determination (R2) for elements such as Mn, Cu, Co, Fe, and Mg by 12.5%, 10.3%, 11%, 10%, and 8.4%, respectively. Hence, our multi-target method can improve the accuracy of predicting 10-element concentrations compared to single-target regression.

Novel lignin-based extracellular barrier in glandular trichome.

Successful biochemical reactions in organisms necessitate compartmentalization of the requisite components. Glandular trichomes (GTs) act as compartments for the synthesis and storage of specialized compounds. These compounds not only are crucial for the survival of plants under biotic and abiotic stresses but also have medical and commercial value for humans. However, the mechanisms underlying compartmentalization remain unclear. Here we identified a novel structure that is indispensable for the establishment of compartments in cucumber GTs. Silica, a specialized compound, is deposited on the GTs and is visible on the surface of the fruit as a white powder, known as bloom. This deposition provides resistance against pathogens and prevents water loss from the fruits1. Using the cucumber bloomless mutant2, we discovered that a lignin-based cell wall structure in GTs, named 'neck strip', achieves compartmentalization by acting as an extracellular barrier crucial for the silica polymerization. This structure is present in the GTs of diverse plant species. Our findings will enhance the understanding of the biosynthesis of unique compounds in trichomes and provide a basis for improving the production of compounds beneficial to humans.

IMA peptides regulate root nodulation and nitrogen homeostasis by providing iron according to internal nitrogen status.

Legumes control root nodule symbiosis (RNS) in response to environmental nitrogen availability. Despite the recent understanding of the molecular basis of external nitrate-mediated control of RNS, it remains mostly elusive how plants regulate physiological processes depending on internal nitrogen status. In addition, iron (Fe) acts as an essential element that enables symbiotic nitrogen fixation; however, the mechanism of Fe accumulation in nodules is poorly understood. Here, we focus on the transcriptome in response to internal nitrogen status during RNS in Lotus japonicus and identify that IRON MAN (IMA) peptide genes are expressed during symbiotic nitrogen fixation. We show that LjIMA1 and LjIMA2 expressed in the shoot and root play systemic and local roles in concentrating internal Fe to the nodule. Furthermore, IMA peptides have conserved roles in regulating nitrogen homeostasis by adjusting nitrogen-Fe balance in L. japonicus and Arabidopsis thaliana. These findings indicate that IMA-mediated Fe provision plays an essential role in regulating nitrogen-related physiological processes.

UAV-based individual Chinese cabbage weight prediction using multi-temporal data.

The use of unmanned aerial vehicles (UAVs) has facilitated crop canopy monitoring, enabling yield prediction by integrating regression models. However, the application of UAV-based data to individual-level harvest weight prediction is limited by the effectiveness of obtaining individual features. In this study, we propose a method that automatically detects and extracts multitemporal individual plant features derived from UAV-based data to predict harvest weight. We acquired data from an experimental field sown with 1196 Chinese cabbage plants, using two cameras (RGB and multi-spectral) mounted on UAVs. First, we used three RGB orthomosaic images and an object detection algorithm to detect more than 95% of the individual plants. Next, we used feature selection methods and five different multi-temporal resolutions to predict individual plant weights, achieving a coefficient of determination (R2) of 0.86 and a root mean square error (RMSE) of 436 g/plant. Furthermore, we achieved predictions with an R2 greater than 0.72 and an RMSE less than 560 g/plant up to 53 days prior to harvest. These results demonstrate the feasibility of accurately predicting individual Chinese cabbage harvest weight using UAV-based data and the efficacy of utilizing multi-temporal features to predict plant weight more than one month prior to harvest.

Inhibition of NPR1 Leads to Shoot Growth Improvement under Low-Calcium Conditions in Arabidopsis.

Under low-Ca conditions, plants accumulate salicylic acid (SA) and induce SA-responsive genes. However, the relationship between SA and low-Ca tolerance remains unclear. Here, we demonstrated that the inhibition or suppression of nonexpressor of pathogenesis-related 1 (NPR1) activity, a major regulator of the SA signaling pathway in the defense response, improves shoot growth under low-Ca conditions. Furthermore, mutations in phytoalexin-deficient 4 (PAD4) or enhanced disease susceptibility 1 (EDS1), which are upstream regulators of NPR1, improved shoot growth under low-Ca conditions, suggesting that NPR1 suppressed growth under low-Ca conditions. In contrast, growth of SA induction-deficient 2-2 (sid2-2), which is an SA-deficient mutant, was sensitive to low Ca levels, suggesting that SA accumulation by SID2 was not related to growth inhibition under low-Ca conditions. Additionally, npr1-1 showed low-Ca tolerance, and the application of tenoxicam-an inhibitor of the NPR1-mediated activation of gene expression-also improved shoot growth under low Ca conditions. The low-Ca tolerance of double mutants pad4-1, npr1-1 and eds1-22 npr1-1 was similar to that of the single mutants, suggesting that PAD4 and EDS1 are involved in the same genetic pathway in suppressing growth under low-Ca conditions as NPR1. Cell death and low-Ca tolerance did not correlate among the mutants, suggesting that growth improvement in the mutants was not due to cell death inhibition. In conclusion, we revealed that NPR1 suppresses plant growth under low-Ca conditions and that the other SA-related genes influence plant growth and cell death.

Early differentiation of Casparian strip mediated by nitric oxide is required for efficient K transport under low K conditions in Arabidopsis.

The Casparian strip (CS) is a cell wall modification made of lignin that functions as an apoplastic barrier in the root endodermis to restrict nutrient and water transport between the soil and stele. CS formation is affected by nutritional conditions, and its physiological roles have been discussed. This study found that low K condition affects CS permeability, lignin deposition, and MYB36 mRNA accumulation. To understand the mechanism underlying these findings, we focused on nitric oxide (NO). NO is known to act as a signaling molecule and participates in cell wall synthesis, especially for lignin composition. However, the mechanism by which NO affects lignin deposition and corrects CS formation in the plant roots remains unclear. Through combining fluorescent observation with histological stains, we demonstrated that the root endodermal cell lignification response to low-potassium (K) conditions is mediated by NO through the MYB36-associated lignin-polymerizing pathway. Furthermore, we discovered the noteworthy ability of NO to maintain nutrient homeostasis for adaptation to low K conditions by affecting the correct apoplastic barrier formation of CS. Collectively, our results suggest that NO is required for the lignification and apoplastic barrier formation in the root endodermis during adaptation to low K conditions, which revealing the novel physiological roles of CS under low nutrient conditions and making a significant contribution to CS biology.

NAC103 mutation alleviates DNA damage in an Arabidopsis thaliana mutant sensitive to excess boron.

Excess boron (B) is toxic to plants and thereby causes DNA damage and cell death in root meristems. However, the underlying mechanisms which link boron and DNA damage remain unclear. It has been reported that the rpt5a-6 mutant of the 26S proteasome is sensitive to excess boron, resulting in more frequent cell death in root meristem and reduced root elongation. In this study, we showed that a reduction in root growth in the rpt5a mutant in the presence of high boron levels is repressed by a mutation in NAC domain containing transcription factor NAC103, a substrate of the proteasome, which functions in the unfolded protein response pathway. The mutation in NAC103 alleviated excess-B-induced DNA damage and cell death in root meristems of the rpt5a mutant. Superoxide ( O 2 - ) staining with nitroblue tetrazolium revealed that boron stress causes O 2 - accumulation in root tips, which was higher in the rpt5a-6 mutant, whereas the accumulation was lower in the rpt5a-6 nac103-3 double mutant. Our work demonstrates the overall involvement of NAC103 in maintaining healthy root meristem under excess boron conditions in the absence of RPT5A proteasome subunit.

Boric acid transport activity of marine teleost aquaporins expressed in Xenopus oocytes.

Marine teleosts ingest large amounts of seawater containing various ions, including 0.4 mM boric acid, which can accumulate at toxic levels in the body. However, the molecular mechanisms by which marine teleosts absorb and excrete boric acid are not well understood. Aquaporins (Aqps) are homologous to the nodulin-like intrinsic protein (NIP) family of plant boric acid channels. To investigate the potential roles of Aqps on boric acid transport across the plasma membrane in marine teleosts, we analyzed the function of Aqps of Japanese pufferfish (Takifugu rubripes) expressed in Xenopus laevis oocytes. Takifugu genome database contains 16 genes encoding the aquaporin family members (aqp0a, aqp0b, aqp1aa, aqp1ab, aqp3a, aqp4a, aqp7, aqp8bb, aqp9a, aqp9b, aqp10aa, aqp10bb, aqp11a, aqp11b, aqp12, and aqp14). When T. rubripes Aqps (TrAqps) were expressed in X. laevis oocytes, a swelling assay showed that boric acid permeability was significantly increased in oocytes expressing TrAqp3a, 7, 8bb, 9a, and 9b. The influx of boric acid into these oocytes was also confirmed by elemental quantification. Electrophysiological analysis using a pH microelectrode showed that these TrAqps increase B(OH)3 permeability. These results indicate that TrAqp3a, 7, 8bb, 9a, and 9b act as boric acid transport systems, likely as channels, in marine teleosts.

Role of GSL8 in low calcium tolerance in Arabidopsis thaliana.

Calcium (Ca) deficiency affects the yields and quality of agricultural products. Susceptibility to Ca deficiency varies among crops and cultivars; however, its genetic basis remains largely unknown. Genes required for low Ca tolerance in Arabidopsis thaliana have been identified. In this study, we identified a novel gene required for low Ca tolerance in A. thaliana. We isolated a mutant sensitive to low Ca concentrations and identified Glucan synthase-like (GSL) 8 as a gene responsible for low Ca tolerance. GSL8 is a paralog of the previously identified low Ca tolerance gene GSL10, which encodes ß-1,3 glucan(callose) synthase. Under low Ca conditions, the shoot growth of gsl8 mutants were inhibited compared to wild-type plants. A grafting experiment indicated that the shoot, but not root, genotype was important for the shoot growth phenotype. The ectopic accumulation of callose under low Ca conditions was reduced in gsl8 mutants. We further investigated the interaction between GSL8 and GSL10 by testing the gsl8 gsl10 double mutant for sensitivity to low Ca concentrations. The double mutant exhibited a more severe phenotype than the single mutant under 0.3 mM Ca, indicating additive effects of GSL8 and GSL10 with respect to low Ca tolerance. These results establish that GSL genes are required for low Ca tolerance in A. thaliana.

Root-specific activation of plasma membrane H+-ATPase 1 enhances plant growth and shoot accumulation of nutrient elements under nutrient-poor conditions in Arabidopsis thaliana.

Plasma membrane (PM) H+-ATPase contributes to nutrient uptake and stomatal opening by creating proton gradient across the membrane. Previous studies report that a dominant mutation in the OPEN STOMATA2 locus (OST2-2D) constitutively activates Arabidopsis PM H+-ATPase 1 (AHA1), which enlarges proton motive force for root nutrient uptake. However, the stomatal opening is also constitutively enhanced in the ost2-2D, causing drought hypersensitivity. To develop plants with improved nutrient acquisition and normal stomatal movement, we generated grafted plants (scion/rootstock: Col-0 (WT)/ost2-2D), and compared their growth, nutrient element content, and transcriptomes with those of control plants (WT/WT) under nutrient-rich or nutrient-poor conditions. WT/ost2-2D shoots had larger weights, rosette diameter, leaf blade area, and content of C, N, K, Ca, S, P, Mg, Na, Mn, B, Co, and Mo under nutrient-poor conditions compared with WT/WT shoots. The root weights and primary root length were greater in WT/ost2-2D plants than in WT/WT plants under both nutrient conditions. Root expression of the high-affinity nitrate transporter NRT2.1, potassium transporter HAK5, and divalent cation transporter IRT1 was higher in WT/ost2-2D plants than in WT/WT plants under nutrient-poor conditions. These results suggest that root-specific activation of PM H+-ATPase enhances plant growth by increasing root uptake of nutrient elements under nutrient-poor conditions. Our study presents a novel approach to improving nutrient uptake efficiency in crops for low-input sustainable agriculture.

Golgi-Localized OsFPN1 is Involved in Co and Ni Transport and Their Detoxification in Rice.

Cobalt (Co) and nickel (Ni) are beneficial and essential elements for plants, respectively, with the latter required for urease activity, which hydrolyzes urea into ammonium in plants. However, excess Co and Ni are toxic to plants and their transport mechanisms in rice are unclear. Here, we analyzed an ethyl methanesulfonate (EMS)-mutagenized rice mutant, 1187_n, with increased Co and Ni contents in its brown rice and shoots. 1187_n has a mutation in OsFPN1, which was correlated with a high Co and Ni phenotype in F2 crosses between the parental line and mutant. In addition, CRISPR/Cas9 mutants exhibited a phenotype similar to that of 1187_n, demonstrating that OsFPN1 is the causal gene of the mutant. In addition to the high Co and Ni in brown rice and shoots, the mutant also exhibited high Co and Ni concentrations in the xylem sap, but low concentrations in the roots, suggesting that OsFPN1 is involved in the root-to-shoot translocation of Co and Ni. The growth of 1187_n and CRISPR/Cas9 lines were suppressed under high Co and Ni condition, indicating OsFPN1 is required for the normal growth under high Co and Ni. An OsFPN1-green fluorescent protein (GFP) fusion protein was localized to the Golgi apparatus. Yeast carrying GFP-OsFPN1 increased sensitivity to high Co contents and decreased Co and Ni accumulation. These results suggest that OsFPN1 can transport Co and Ni and is vital detoxification in rice.

Arabidopsis Glucan Synthase-Like1 (GSL1) Is Required for Tolerance to Low-Calcium Conditions and Exhibits a Function Comparable to GSL10.

Crops that exhibit symptoms of calcium (Ca) deficiency constitute a major agricultural problem. Molecular breeding of resistant cultivars is a promising method for overcoming this problem. However, the involved genes must first be identified. Here, we show that the glucan synthase-like (GSL) 1 gene is essential for low-Ca tolerance in Arabidopsis thaliana. GSL1 is homologous to GSL10, which we previously showed was essential for low-Ca tolerance. Under low-Ca conditions, gsl1 mutants exhibit reduced growth and the onset of necrosis in new leaves. These symptoms are typical of Ca-deficient crops. A grafting experiment suggested that the shoot genotype, but not the root genotype, was important for the suppression of shoot necrosis. The ectopic accumulation of callose under low-Ca conditions was significantly reduced in gsl1 mutants compared with wild-type plants. Because the corresponding single-mutant phenotypes are similar, we investigated the interaction between GSL1 and GSL10 by testing the gsl1 gsl10 double mutant for sensitivity to low-Ca conditions. The double mutant exhibited a more severe phenotype than did the single mutants, indicating that the effects of GSL1 and GSL10 on low-Ca tolerance are additive. Because GSL genes are highly conserved within the plant kingdom, the GSL loci may be useful for breeding low-Ca tolerant crops.

OsVIT2 Mutation Increases Fe and Zn of Grain Without Compromising the Growth in Paddy Field.

Nearly 2 billion people who reside in developing countries are suffering from nutrient deficiency, also known as hidden hunger. A hidden hunger includes iron (Fe) and zinc (Zn) deficiency. One of the most efficient solutions to hidden hunger is the biofortification of crops through breeding. In this study, we characterized the mutant 1095_k, which has high grain Fe (~1.4-fold) and Zn (~1.2-fold) concentration compared with wild-type plants for a 5-year field trial. The yield components of 1095_k are similar to wild-type plants in a paddy field. In addition, 1095_k has a non-sense mutation in OsVIT2, a vacuolar localized Fe transporter. F2 crosses between 1095_k and wild type having the mutation showing higher grain Fe and Zn concentration. In contrast, plants without the mutation showed similar element concentrations as the wild type. These results suggest that OsVIT2 would be responsible for high Fe and Zn of grain and the 1095_k would be a useful breeding material for the biofortification of Fe and Zn.

Systemic Regulation of Iron Acquisition by Arabidopsis in Environments with Heterogeneous Iron Distributions.

Nutrient distribution within the soil is generally heterogeneous. Plants, therefore, have evolved sophisticated systemic processes enabling them to optimize their nutrient acquisition efficiency. By organ-to-organ communication in Arabidopsis thaliana, for instance, iron (Fe) starvation in one part of a root drives the upregulation of a high-affinity Fe-uptake system in other root regions surrounded by sufficient levels of Fe. This compensatory response through Fe-starvation-triggered organ-to-organ communication includes the upregulation of Iron-regulated transporter 1 (IRT1) gene expression on the Fe-sufficient side of the root; however, the molecular basis underlying this long-distance signaling remains unclear. Here, we analyzed gene expression by RNA-seq analysis of Fe-starved split-root cultures. Genome-wide expression analysis showed that localized Fe depletion in roots upregulated several genes involved in Fe uptake and signaling, such as IRT1, in a distant part of the root exposed to Fe-sufficient conditions. This result indicates that long-distance signaling for Fe demand alters the expression of a subset of genes responsible for Fe uptake and coumarin biosynthesis to maintain a level of Fe acquisition sufficient for the entire plant. Loss of IRON MAN/FE-UPTAKE-INDUCING PEPTIDE (IMA/FEP) leads to the disruption of compensatory upregulation of IRT1 in the root surrounded by sufficient Fe. In addition, our split-root culture-based analysis provides evidence that the IMA3/FEP1-MYB10/72 pathway mediates long-distance signaling in Fe homeostasis through the regulation of coumarin biosynthesis. These data suggest that the signaling of IMA/FEP, a ubiquitous family of metal-binding peptides, is critical for organ-to-organ communication in response to Fe starvation under heterogeneous Fe conditions in the surrounding environment.

Sorghum Ionomics Reveals the Functional SbHMA3a Allele that Limits Excess Cadmium Accumulation in Grains.

Understanding uptake and redistribution of essential minerals or sequestering of toxic elements is important for optimized crop production. Although the mechanisms controlling mineral transport have been elucidated in rice and other species, little is understood in sorghum-an important C4 cereal crop. Here, we assessed the genetic factors that govern grain ionome profiles in sorghum using recombinant inbred lines (RILs) derived from a cross between BTx623 and NOG (Takakibi). Pairwise correlation and clustering analysis of 22 elements, measured in sorghum grains harvested under greenhouse conditions, indicated that the parental lines, as well as the RILs, show different ionomes. In particular, BTx623 accumulated significantly higher levels of cadmium (Cd) than NOG, because of differential root-to-shoot translocation factors between the two lines. Quantitative trait locus (QTL) analysis revealed a prominent QTL for grain Cd concentration on chromosome 2. Detailed analysis identified SbHMA3a, encoding a P1B-type ATPase heavy metal transporter, as responsible for low Cd accumulation in grains; the NOG allele encoded a functional HMA3 transporter (SbHMA3a-NOG) whose Cd-transporting activity was confirmed by heterologous expression in yeast. BTx623 possessed a truncated, loss-of-function SbHMA3a allele. The functionality of SbHMA3a in NOG was confirmed by Cd concentrations of F2 grains derived from the reciprocal cross, in which the NOG allele behaved in a dominant manner. We concluded that SbHMA3a-NOG is a Cd transporter that sequesters excess Cd in root tissues, as shown in other HMA3s. Our findings will facilitate the isolation of breeding cultivars with low Cd in grains or in exploiting high-Cd cultivars for phytoremediation.

Regulation of ammonium acquisition and use in Oryza longistaminata ramets under nitrogen source heterogeneity.

Oryza longistaminata, a wild rice, vegetatively reproduces and forms a networked clonal colony consisting of ramets connected by rhizomes. Although water, nutrients, and other molecules can be transferred between ramets via the rhizomes, inter-ramet communication in response to spatially heterogeneous nitrogen availability is not well understood. We studied the response of ramet pairs to heterogeneous nitrogen availability using a split hydroponic system that allowed each ramet root to be exposed to different conditions. Ammonium uptake was compensatively enhanced in the sufficient-side root when roots of the ramet pairs were exposed to ammonium-sufficient and ammonium-deficient conditions. Comparative transcriptome analysis revealed that a gene regulatory network for effective ammonium assimilation and amino acid biosynthesis was activated in the sufficient-side roots. Allocation of absorbed nitrogen from the nitrogen-sufficient to the nitrogen-deficient ramets was rather limited. Nitrogen was preferentially used for newly growing axillary buds on the sufficient-side ramets. Biosynthesis of trans-zeatin (tZ), a cytokinin, was upregulated in response to the nitrogen supply, but tZ appeared not to target the compensatory regulation. Our results also implied that the O. longistaminata putative ortholog of rice (Oryza sativa) C-terminally encoded peptide1 plays a role as a nitrogen-deficient signal in inter-ramet communication, providing compensatory upregulation of nitrogen assimilatory genes. These results provide insights into the molecular basis for efficient growth strategies of asexually proliferating plants growing in areas where the distribution of ammonium ions is spatially heterogeneous.

CASP microdomain formation requires cross cell wall stabilization of domains and non-cell autonomous action of LOTR1.

Efficient uptake of nutrients in both animal and plant cells requires tissue-spanning diffusion barriers separating inner tissues from the outer lumen/soil. However, we poorly understand how such contiguous three-dimensional superstructures are formed in plants. Here, we show that correct establishment of the plant Casparian Strip (CS) network relies on local neighbor communication. We show that positioning of Casparian Strip membrane domains (CSDs) is tightly coordinated between neighbors in wild-type and that restriction of domain formation involves the putative extracellular protease LOTR1. Impaired domain restriction in lotr1 leads to fully functional CSDs at ectopic positions, forming 'half strips'. LOTR1 action in the endodermis requires its expression in the stele. LOTR1 endodermal expression cannot complement, while cortex expression causes a dominant-negative phenotype. Our findings establish LOTR1 as a crucial player in CSD positioning acting in a directional, non-cell-autonomous manner to restrict and coordinate CS positioning.

Boric acid transport activity of human aquaporins expressed in Xenopus oocytes.

Boric acid is a vital micronutrient that is toxic at high concentrations in animals. However, the mechanisms underlying boric acid transport in animal cells remain unclear. To identify the plasma membrane boric acid channels in animals, we analyzed the function of human aquaporins (AQPs), which are homologous to the nodulin-like intrinsic protein family of plant boric acid channels. When human AQPs were expressed in Xenopus laevis oocytes, the results of the swelling assay showed that boric acid permeability significantly increased in oocytes expressing AQP3, 7, 8, 9, and 10, but not in those expressing AQP1, 2, 4, and 5. The boric acid influxes of these oocytes were also confirmed by elemental quantification. Electrophysiological analysis using a pH microelectrode showed that these AQPs transported boric acid (B(OH)3 ) but not borate ions (B(OH)4- ). These results indicate that AQP3, 7, 8, 9, and 10 act as boric acid transport systems, likely as channels in humans.

Rosmarinic Acid and Sodium Citrate Have a Synergistic Bacteriostatic Effect against Vibrio Species by Inhibiting Iron Uptake.

BACKGROUND: New strategies are needed to combat multidrug-resistant bacteria. The restriction of iron uptake by bacteria is a promising way to inhibit their growth. We aimed to suppress the growth of Vibrio bacterial species by inhibiting their ferric ion-binding protein (FbpA) using food components. METHODS: Twenty spices were selected for the screening of FbpA inhibitors. The candidate was applied to antibacterial tests, and the mechanism was further studied. RESULTS: An active compound, rosmarinic acid (RA), was screened out. RA binds competitively and more tightly than Fe3+ to VmFbpA, the FbpA from V. metschnikovii, with apparent KD values of 8 µM vs. 17 µM. Moreover, RA can inhibit the growth of V. metschnikovii to one-third of the control at 1000 µM. Interestingly, sodium citrate (SC) enhances the growth inhibition effect of RA, although SC only does not inhibit the growth. The combination of RA/SC completely inhibits the growth of not only V. metschnikovii at 100/100 µM but also the vibriosis-causative pathogens V. vulnificus and V. parahaemolyticus, at 100/100 and 1000/100 µM, respectively. However, RA/SC does not affect the growth of Escherichia coli. CONCLUSIONS: RA/SC is a potential bacteriostatic agent against Vibrio species while causing little damage to indigenous gastrointestinal bacteria.