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Rice (Oryza sativa L.) is a main food crop in China and is crucial for the maintenance of national food security. The growth of rice seedling roots is regulated by a variety of genes and is closely related to abscisic acid (ABA) metabolism and ABA signaling pathways. In this study, we found that OsABT could increase the length of rice root tip meristem cells and upregulate root development-related genes, thereby alleviating ABA’s inhibitory effects on rice root growth and seed germination. The overexpression of OsABT reduced the ABA content by downregulating ABA synthesis genes (OsNCED3 and OsNCED5) and upregulating the ABA catabolic gene (OsABA8ox2). In addition, OsABT interacted with OsPYL4, OsPYL10, and OsABIL2 via the ABA signal transduction pathway. By inhibiting the expression of positive regulatory genes (OsPYL9 and Rab16a) and increasing the expression of a negative regulatory gene (OsABIL1), OsABT negatively regulates the ABA signal transduction pathway. Transcriptome analysis revealed that OsABT inhibited the activity of Gene Ontology entries in response to ABA. Thus, OsABT increased the length of the rice root meristem, reduced the accumulation of ABA in the roots, and negatively regulated the ABA signal transduction pathway by interacting with key proteins in this pathway, ultimately relieving the inhibitory effect of ABA on rice root length and seed germination.

The herbicide fluridone (1-methyl-3-phenyl-5-[3-trifluoromethyl (phenyl)]-4(1H)-pyridone) interferes with carotenoid biosynthesis in plants by inhibiting the conversion of phytoene to phytofluene. Fluridone also indirectly inhibits the biosynthesis of abscisic acid and strigolactones, and therefore, our study indirectly addresses the effect of reduced ABA on the roots and leaf buds development in stem cuttings of Salix babylonica L. ‘Tortuosa’. The stem cuttings were kept in distilled water (control) or in a solution of fluridone (10 mg/L) in natural greenhouse light and temperature conditions. During the experiments, morphological observations were carried out on developing roots and leaf buds, as well as their appearance and growth. After three weeks of continuous treatments, adventitious roots and leaf buds were collected and analysed. Identification and analysis of anthocyanins were carried out using micro-HPLC-MS/MS-TOF, while HPLC-MS/MS was used to analyse phenolic acids, flavonoids and salicinoids. The fluridone applied significantly inhibited root growth, but the number or density of roots was higher compared to the control. Contents of salicortin and salicin were several dozen times higher in leaf buds than in roots of willow. Fluridone increased the content of salicortin in roots and leaf buds and declined the level of salicin in buds. Fluridone also declined the content of most anthocyanins in roots but enhanced their content in buds, especially cyanidin glucoside, cyanidin galactoside and cyanidin rutinoside. Besides, fluridone markedly decreased the level of chlorophylls and carotenoids in the leaf buds. The results indicate that applied fluridone solution reduced root growth, caused bleaching of leaf buds, and markedly affected the content of secondary metabolites in the adventitious roots and leaf buds of S. babylonica stem cuttings. The paper presents and discusses in detail the significance of fluridone’s effects on physiological processes and secondary metabolism.

Rhodotypos scandens (Thunb.) Makino is known to have a seed dispersal that is thick and stony (endocarp + seeds) and has potential as a landscaping tree seed. In several Rosaceae species, seeds are covered with a hard endocarp, making the internal seeds water-impermeable and germination difficult. Here, we analyzed the morphoanatomical traits and germination properties of R. scandens seeds. To identify ideal seed propagation conditions, we immersed R. scandens seeds in sulfuric acid for varying durations and subjected them to phytohormone (gibberellic acid A3 and fluridone) and a cold stratification (CS) (5 °C) treatment after endocarp removal (ER). The R. scandens stony seeds did not increase in mass by ≥25.0%. Following ER, the seed mass increased by ≥50.0% with water absorption when compared to the initial dry mass. Seed surfaces showed damage and cracks through scarification after 1 h of immersion in sulfuric acid, failing to germinate. A combination of ER, phytohormone treatment, and CS improved seed germination compared to ER alone (26.0 ± 5.3%). Overall, R. scandens seeds showed a dispersal with a hard endocarp from the parent plant, and a pre-treatment with ER, phytohormones, and CS was required for effective seed propagation.

Abstract Fluridone is widely used as a herbicide for controlling invasive aquatic plants such as hydrilla in surface water bodies. When applied on surface waters fluridone can attach to bed sediment, requiring rigorous extraction methods prior to analysis. Currently, very limited information exists in terms of fluridone residue detection in delta sediment. In this study, we researched fluridone detection in both water and sediment. To extract fluridone from sediment, here we have tested two extraction methods: (1) a rotavapor method (RM); and (2) a quick, easy, cheap, effective, rugged and safe (QuEChERS) method (QM). The extraction results of RM were compared with those of QM. To quantify fluridone concentrations in extracts, a high-performance liquid chromatography (HPLC)-UV detector was used. HPLC separation was achieved using an Allure C18 5 µm 150 × 4.6 mm column with a mobile phase composed of acetonitrile and water (60:40, v/v). The UV detector was operated at 237 nm. The method was tested and validated using a series of water and sediment samples taken from Sacramento–San Joaquin Delta in California. The average recovery of fluridone was 73% and 78% using RM and QM respectively. The proposed method can be used for testing fluridone in water and sediment samples.

The phytohormone abscisic acid (ABA) inhibits seed germination and seedling growth and is required for the inception of dormancy. Xanthoxal (also known as xanthoxin) is the first specific biosynthetic precursor of ABA. In this study, a modified method to produce xanthoxal is described. I tested the ability of either xanthoxal or ABA to reinstate dormancy in dormant red rice seeds whose dormancy was broken by fluridone (an inhibitor of the synthesis of carotenoids and, subsequently, ABA). Xanthoxal was shown to have a stronger inhibitory effect on germination than ABA when exogenously provided. Although this could indicate an additional effect of xanthoxal above that expected if xanthoxal were simply converted to ABA in the seed, alternative hypotheses cannot be excluded. One alternative is that exogenous xanthoxal may be trapped inside the cells to a greater extent than exogenous ABA, resulting in an intracellular level of ABA higher than that reached with a direct application of ABA. As a further alternative, exogenous xanthoxal may interfere with ABA action in the apoplast. In this study, following germination, early seedling growth was delayed only if ABA was applied. This suggests that inhibition of early seedling growth, but not of germination, requires extracellular ABA.

Abstract Background Notopterygium incisum is an important Chinese medicinal plant. Its mature seeds have underdeveloped embryos and are physiological dormant. We found the seeds with full developed embryos can germinate after treated by fluridone (FL), an inhibitor of abscisic acid (ABA). In order to understand the molecular mechanisms underlying seed dormancy release by FL, we compared the transcriptomic changes in dormancy release induced by two different methods, FL and cold stratification (CS) in N. incisum. We further analyzed the gene expression patterns involved in seed germination and dormancy using quantitative reverse-transcription PCR. Results RNA-sequence analysis revealed more dramatic changes in the transcriptomes of FL than those in CS, particularly for genes involved in the biosynthesis and regulation of gibberellins (GAs) and ABA. The down-regulation of ABA biosynthesis genes and the dramatic up-regulation of NiCYP707As, an ABA catabolic gene, contributed to the reduced ABA levels in FL. The increased GA3 levels in CS-treated seeds were due to the up-regulation of NiGA3OX. Both NiABI5 (a positive ABA regulator) and NiGAI (a negative regulator of GA) were down-regulated in FL and CS. The upregulation of strigolactones (SLs; the metabolites with the same precursor as ABA) biosynthesis and regulatory genes in both FL- and CS-treated seeds indicates that SLs contribute positively to seed dormancy release in N. incisum. Conclusions Our results indicated that FL- and CS-seed dormancy release possibly depends on two totally different mechanisms: alleviation of the effects of ABA and potentiation of the effects of GA, respectively. However, NiABI5 and NiGAI probably function as common factors integrating the effects of ABA and GA on seed dormancy release.

We examined the response of maturing tomato fruit exposed for 7 days to fluridone (1-methyl-3-phenyl-5-[3-trifluoromethyl(phenyl)]-4(1H)-pyridinone). Fluridone was applied in lanolin paste in the form of a 2–3 mm wide strip from the top to the base of the fruit. As a control, a similar stripe of lanolin was applied in the same way on the opposite side of the same fruit. The content of major carotenoids, as well as flavonoids, and free and bound phenolic acids were determined using a HPLC and HPLC-MS-MS methods. Fluridone almost completely blocked the biosynthesis of lycopene and substantial declined content of ß-carotene and lutein in the tomato fruit. The fluridone caused a decreased content of quercetin, rutin and naringenin, and increased level of epicatechin. The herbicide did not affect the content of p-coumaric acid, but reduced the level of caffeic acid, both free and ester form, and declined the content of free ferulic and chlorogenic acids. Changes in phenolics composition observed for the first time indicate that fluridone interferes with the biosynthesis of further products of the metabolism of p-coumaric acid, both flavonoids and phenolic acids.

Myriophyllum spicatum or Eurasian watermilfoil (hereafter, milfoil) is among the most problematic invasive aquatic plant species throughout much of North America. M. spicatum infestations can result in reduced diversity and abundance of native plant populations. Control of the invader is essential to promoting healthy ecosystems. Several treatment alternatives are available for milfoil control, although cost and efficacy vary significantly, with some treatments resulting in more harm to the native population than no treatment at all. A series of field-based microcosms containing actively growing milfoil were constructed in order to directly compare the impact of two herbicides (2,4-dichlorophenoxyacetic acid and fluridone) and the milfoil weevil (Euhrychiopsis lecontei) on weed control and plant biochemistry. Herbicide concentrations in water, plants, and sediments were monitored, as were weevil population dynamics and resulting invertebrate damage to milfoil stems. The impact of the different treatments on levels of polyphenols, carbohydrates, ash, and overall carbon and nitrogen levels in the milfoil were determined. Total biomass of the untreated milfoil increased by more than 2.7-fold during the 53-day experimental period. Conversely, the biomass of milfoil subjected to chemical or biological treatment either remained constant or decreased significantly during the experiment. The herbicide 2,4-D resulted in nearly 100% milfoil mortality by day 20, whereas fluridone toxicity was significantly slower but reached 75% by the end of the trial. Similarly, milfoil growth in the weevil-amended tanks was somewhat erratic but by the end of the trial, the total plant biomass was 71% less than that of un-amended controls. Although the total biomass remaining at the end of the fluridone and weevil treatments was similar, the carbohydrate and starch content of the shoots in the insect treatment were nearly 4.6- and 4.8-fold greater, respectively, than that of the herbicide treated plants. The higher starch content in insect-treated plants could lead to increased autofragmentation and spread of M. spicatum. However, herbicide treatments are frequently required for several years. Therefore, integrated pest management, which combines the long-term benefits of biological controls with the short-term benefits of herbicides may provide the best solution to the control of M. spicatum and the conservation of native plants.

Carotenoids are lipophilic pigments found in plants and algae, as well as some bacteria, archaea, and fungi that serve two functions—(1) as light harvesting molecules—primary carotenoids, and (2) as antioxidants, acting against reactive oxygen species–secondary carotenoids. Because of their strong antioxidant properties, they are also valuable for the development of anti-aging and photo-protective cosmetic applications. Of particular interest is the carotenoid phytoene, for its colorless and UV absorption characteristics. In this study, we targeted a reduction of phytoene desaturase (PDS) activity with the pigment-inhibiting herbicide 1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]pyridin-4-one (fluridone), which leads to the over-accumulation of phytoene in the recently characterized microalgal strain Chlorococcum sp. (UTEX B 3056). After post-incubation with fluridone, phytoene levels were measured at ~33 ug/mg cell tissue, as opposed to non-detectable levels in control cultures. Hence, the novel microalga Chlorococcum sp. is a viable candidate for the production of the high-value carotenoid phytoene and subsequent applications in cosmeceuticals, as well as more obvious nutraceutical and pharmaceutical applications.

Fluridone (FLU) was a pyrrolidone herbicide that was used for selective weeding in wheat, rice, corn and pasture and was also a biosynthesis inhibitor of abscisic acid (ABA), a significant plant hormone. ABA-promoted callose deposition facilitates rice resistance to pests but whether FLU had the opposite influence was unknown. The effects of FLU on the feeding behavior of the brown planthopper (Nilaparvata lugens Stål; BPH), after feeding with rice plants treated with FLU, were studied, using an electrical penetration graph (EPG). For susceptible rice cultivar (TN1), the duration for which BPH sucked phloem sap (N4 wave duration) after 15 μmol/L of FLU treatment was longer than that of the control but decreased after 30 and 60 μmol/L FLU treatments. Fecundity of BPH treated with 15 μmol/L FLU had no significant change, while the deposition area of callose was significantly decreased. For moderately-resistant rice cultivar (IR42), no differences in BPH feeding behavior and fecundity were observed but the deposition area of callose declined after treated with 15 μmol/L of FLU. These findings suggested that a low concentration of FLU (15 μmol/L) promoted BPH feeding behavior in TN1 but not in IR42 and the response in IR42 appeared to be more complicated, which provided supplementary evidence that ABA promoted plant resistance to BPH.

Tendo em vista a importância das sempre-vivas pelo seu valor ornamental e vulnerabilidade ao extrativismo, pesquisas para garantir a propagação da espécie tornam-se imprescindíveis. Objetivou-se com a pesquisa avaliar se existe associação entre a cor do tegumento e a qualidade de sementes de sempre-vivas, na presença ou ausência de dormência e em diferentes temperaturas. Quatro espécies do gênero Comanthera (C. elegans, C. nitida, C. bisculata e C. sp.) foram separadas com relação a cor do tegumento e em substrato umedecido com água ou solução de fluridone 0,1%, em temperatura alternadas de 10/25 e 15/25° C, avaliando-se a primeira contagem de germinação, germinação e índice de Velocidade de germinação O delineamento experimental utilizado foi inteiramente casualizado, em esquema fatorial 4 x 2 x 2 Representados pelos fatores tegumento (verde, bege, vermelho, marrom), temperatura (10/25 e 15/25° C) e quebra de dormência por fluridone 100 μM (sem ou com)]. De maneira geral, a temperatura alternada de 15/25° C favorece a germinação das sempre-vivas. A germinação e vigor das sementes aumenta com o uso do fluridone. O efeito da cor do tegumento é variável entre as espécies, sendo que maiores taxas de germinação e vigor foram observadas em sementes de cor verde para C. sp. e menores valores em C. bisculata. Para C. nitida e C. elegans a cor do tegumento não influencia na qualidade das sementes. O uso do fluridone favorece e uniformiza a germinação das sementes com diferentes graus de maturidade fisiológica. A temperatura alternada 15/2 ° C é ideal para obtenção de maior germinação e vigor de sementes de sempre-vivas.

Dune reed (DR) and swamp reed (SR) are two ecotypes of reed (Phragmites communis Trin.) that displayed differences in stress tolerance. To uncover the molecular basis for such difference, the effects of heat stress were studied using the calli derived from the two ecotypes. Heat stress caused increased ion leakage, inhibited growth, decreased cell viability, and elevated hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents in the calli of both ecotypes, but DR callus showed better heat tolerance than SR callus. In DR callus, heat stress caused significant increase in the endogenous ABA content but not in SR callus. Application of fluridone (an ABA synthesis inhibitor) aggravated the heat stress damages on the DR callus whereas it had only minimal impact on the SR callus. Exogenous application of ABA alleviated the heat stress symptoms in the calli of both ecotypes. ABA treatment increased the activities of superoxide dismutase, catalase, ascorbate peroxidase and peroxidase, and also decreased H2O2 and MDA contents. These results indicate that the ability of ABA synthesis under heat stress is a key factor attributing to the higher heat tolerance of DR than SR.

The effect of fluridone (or flurochloridone), the inhibitor of carotenoid, chlorophyll and abscisic acid synthesis, on the abscission of Ligustrum vulgare leaves was investigated. Both forms of fluridone inhibited the abscission of petioles when they were applied as a 1.0% concentration in lanolin to the leaf blade. Fluridone was capable of inhibiting abscission even when it was applied to the petiole as late as 7 hours after the blade was cut off. Fluridone applied in lanolin to the apical part of intact pea seedlings or on the cut surface after decapitation of the epicotyl caused albinism of the stipules. The degree of albinism decreased according to the concentration of applied flurodine (from the highest - 0.5% to the lowest - 0.03%) and was higher in intact than in decapitated plants. Albinism also appeared in pea seedlings grown from seeds swollen in differently concentrated solutions of flurochloridone, particularly in the basal part of the shoots. Complete albinism occurred only in plants cultivated from seeds swollen in high concentrations (0.06-0.12%). The lowest concentration (0.007%) stimulated root growth of the pea seedlings, but inhibited epicotyl growth.

O objetivo deste estudo foi avaliar a eficiência do herbicida fluridone no controle de plantas aquáticas submersas (Egeria densa, Egeria najas e Ceratophyllum demersum), assim como seus efeitos sobre algumas características ambientais. A pesquisa foi conduzida no reservatório da Usina Hidrelétrica Eng. Souza Dias (Jupiá), região noroeste do Estado de São Paulo, em uma reentrância denominada lagoa Vírgula. A lagoa foi dividida em nove faixas e seis delas receberam uma aplicação inicial de fluridone para se obter uma concentração de 20 ppb. As aplicações subseqüentes foram dimensionadas para recompor esta concentração. Para o estudo do carreamento do herbicida pelo fluxo de água, foi efetuado o monitoramento das suas concentrações nas nove faixas da lagoa (com e sem aplicação) e em áreas a jusante e a montante. Foram analisados os efeitos do fluridone sobre características ambientais como: turbidez, temperatura da água, condutividade elétrica, concentração de oxigênio, pH e resíduos de fluridone. A eficácia do controle foi avaliada visualmente (pelos sintomas de fitointoxicação nas três espécies estudadas) e pela amostragem de biomassa. Observou-se que o fluridone controlou de forma satisfatória E. najas e E. densa. Quando cessou o efeito do fluridone, aconteceu a reinfestação de E. densa e E. najas. Não houve controle de C. demersum. O fluridone não produziu efeitos adversos sobre as características de qualidade ambiental estudadas.This study aimed to evaluate the efficacy of the herbicide fluridone to control submersed aquatic weeds (Egeria densa, Egeria najas and Ceratophyllum demersum), as well as its effects on some environmental characteristics. The research was carried out in the reservoir of Eng. Souza Dias (Jupiá) Hydro-elecric plant power, Station in northwestern São Paulo, Brazil, in Lagoa Vírgula bay. The bay was divided in nine zones and six of them received an initial application of fluridone to achieve the concentration of 20 ppb. The amounts of fluridone used in all other applications were calculated to restore the 20 ppb concentration. In order to study the herbicide loss due to water flow, fluridone concentrations were monitored in all treated and non-treated zones of the bay and in upstream and downstream areas. Fluridone effects on some environmental characteristics, such as turbidity, water temperature, electric conductivity, oxigen concentration, pH and fluridone residues were evaluated. Visual evaluation of phytotoxicity symptoms on the three species studied and biomass evaluations were also carried out. Fluridone controlled the submersed aquatic plants E. najas and E. densa. E. densa and E. najas regrew as the effect of fluridone ended while C. demersum was not controlled. Fluridone did not produce any negative effect on the environmental quality characteristics studied in the treated areas.

O objetivo deste trabalho foi desenvolver um método de análise de resíduos do herbicida fluridone em peixes. O herbicida foi extraído do peixe (partes comestíveis), concentrado em colunas de florisil e então analisado em cromatógrafo líquido com detector de UV visível a 313 nm. Os coeficientes de correlação obtidos para linearidade do detector e do método foram de 0,99983 e 0,99987, respectivamente. Com o método descrito foi possível extrair, separar e identificar com eficiência o herbicida fluridone das amostras de peixe, o qual apresentou médias de percentagens de recuperação variando de 60 a 73%. O limite de detecção foi de 20 mg kg-1.The aim of this research was to develop an analytical method to detect and quantify residues of fluridone in fish. The herbicide was extracted from edible parts of fish, concentrated in florisil cartridge and then analyzed by HPLC. The detection and quantification were performed by UV absorbance (313 nm). The correlation values obtained for the linearity of the detector and the method were 0,99983 and 0,99987, respectively. The recovery coefficient ranged from 60 to 73%. The detection limit was 20 mg kg-1.

Este projeto teve por objetivo avaliar a eficácia de herbicidas para controle de plantas aquáticas submersas das espécies Egeria densa e Egeria najas. O estudo foi realizado em três etapas consecutivas: em laboratório, em caixas d'água e numa represa de pequeno porte, sem fluxo de água. Na primeira etapa, avaliou-se a eficiência de 23 herbicidas utilizados em áreas agrícolas e disponíveis no mercado brasileiro. As elevadas concentrações em que os herbicidas foram efetivos inviabilizam programas de controle fundamentados em uma única aplicação. No experimento em caixas d'água, foram avaliados os efeitos de doses crescentes de fluridone, nas formulações líquida e granulada, no controle de Egeria densa e Egeria najas. Foram testadas as concentrações de 10, 20, 40, 80 e 150 ppb de fluridone na formulação líquida e 20, 40, 80 e 150 ppb na granulada. Após uma única aplicação, os resultados indicaram que o fluridone, nas concentrações de 80 e 150 ppb, em ambas as formulações, foi eficaz no controle dessas duas espécies. No experimento em represa de pequeno porte sem fluxo de água, avaliou-se o efeito da manutenção das concentrações de fluridone no controle de Egeria najas. Uma represa de 1.980 m² foi tratada com sete aplicações de fluridone, na formulação líquida, visando a manutenção das concentrações do ingrediente ativo na água entre 10 e 20 ppb. Os resultados indicaram que o controle proporcionado pelo herbicida foi superior a 99%. Não houve modificação significativa nas características relacionadas à qualidade da água.The objective of this research was to evaluate the efficacy of herbicides in controlling the submerged aquatic weeds Egeria densa and Egeria najas. The study was carried out in three consecutive stages: in the laboratory, in tanks and in a small pond without water flow. In the first stage, the efficacy of 23 herbicides used in agriculture and available in Brazil was evaluated. Results showed that none of the herbicides could be used to control these species, if applied just once. In the tank experiment the effect of increasing rates of fluridone (in two formulations: liquid and pellet), on the control of the species Egeria densa and Egeria najas was evaluated. Concentrations of 10, 20, 40, 80 and 150 ppb of the liquid formulation and 20, 40, 80 and 150 ppb of pellet formulations were used. After a single application, results showed that fluridone, at 80 and 150 ppb of both liquid and pellet formulations, was efficient in controlling both species. In the small pond experiment, the effect of keeping fluridone concentrations for an extended period of time on the control of Egeria najas was evaluated. A 1,980 m² pond was treated seven times to keep herbicide concentrations in water between 10 and 20 ppb. Results showed that control was higher than 99%. No meaningful change in water quality was found during the experiment.

Although crosstalk between cytosolic and plastidic terpenoid pathways has been validated in many plant species, we report here for the first time a striking elevation of the nucleus-encoded artemisinin biosynthesis relevant DBR2 mRNA following the incubation of plants with fosmidomycin (FM). FM decreased singlet oxygen (1O2) scavengers such as β-carotene and α-tocopherol and subsequently invoked 1O2 burst. The treatment of plants with fluridone (FD) neither decreased α-tocopherol content nor triggered 1O2 emission. In conclusion, FM can up-regulate 1O2-sensitive nuclear genes responsible for artemisinin biogenesis by mitigating the accumulation of plastidic scavenging terpenoids, thereby eliciting 1O2 generation and initiating 1O2 retrograde signaling.