Rice Bakanae Disease Research Articles

FfCOX17 is Involved in Fumonisins Production, Growth, Asexual Reproduction, and Fungicide Sensitivity in Fusarium fujikuroi.

Fusarium fujikuroi, a causal agent of Rice Bakanae Disease, produces secondary metabolites such as gibberellin, pigments bikaverin, and mycotoxins fumonisins. Fumonisins produced by F. fujikuroi pose a severe threat to human and animal health. The copper chaperone protein plays a critical role in different growth stages of plants, fungi, and yeasts, but their functions and regulation in fumonisin biosynthesis are still unclear. Here, a copper chaperone protein, FfCOX17, was identified in F. fujikuroi. The FfCOX17 deletion mutant (∆FfCOX17) exhibited decreased vegetative growth and asexual reproduction. The transcriptional level of the FfFUM2 gene was significantly induced in ∆FfCOX17, and the fumonisin production in ∆FfCOX17 mutants was significantly increased compared to wild-type F. fujikuroi, but the pathogenicity of ∆FfCOX17 mutants was unaffected, which may be caused by the no significantly changed gibberellin content. ∆FfCOX17 showed decreased sensitivity to oxidative stress, osmotic stress, and increased sensitivity to cell wall stress, heat shock stress, and high concentration glucose. In addition, ∆FfCOX17 also showed increased sensitivity to fungicide fluazinam and fludioxonil, and decreased sensitivity to phenamacril and prochloraz. Taken together, this study suggested that FfCOX17 is critical for fumonisin production, vegetative growth, asexual reproduction, and fungicide sensitivity, but is not required for the virulence function of F. fujikuroi on rice.

Morphological and molecular characterization of Fusarium sp. causing Bakanae disease of rice (Oryza sativa) in western Uttar Pradesh, India

Rice (Oryza sativa L.) is considered as one of the main staple food grains. The Asian countries lead in production and consumption of rice i.e. more than 90% rice is produced and consumed in Asia. India is considered as one of the leading exporters of rice. Rice is affected by number of diseases and pests and among the several diseases which infects the rice crop, a fungal disease commonly known as Bakanae disease or Foot rot of rice is caused by Fusarium moniliforme (Gibberella fujikuroi) fungus. It is one of the important diseases of rice and leads to severe losses in rice yield particularly in basmati rice. According to some previous reports, some other Fusarium species were also found to be causing the disease. Therefore, the following study was conducted in the year 2018–19 at Sardar Vallabhbhai Patel University of Agriculture & Technology, Meerut, Uttar Pradesh, India, to find out and identify the Fusarium sp.mainly associated with the Bakanae disease in western Uttar Pradesh. Twelve isolates of Fusarium moniliforme were collected and isolated from different locations of western Uttar Pradesh and their characterization of morphological and molecular characters was carried out. Morphological characters, like fungal growth type, pigmentation, radial growth, colony characters were studied and compared with the standard culture of Fusarium moniliforme obtained from ITCC, New Delhi. The molecular characterization was done with specific primers. The results indicated that Bakanae disease of rice in western Uttar Pradesh is primarily caused by Fusarium moniliforme. The study also confirms that identification based on morphological and culture characteristics must be coupled with molecular characteristics for proper identification of specific fungal sp. causing Bakanae disease

Decreased sensitivity of <i>Fusarium fujikuroi</i> Nirenberg isolates from Hyogo Prefecture to Pefurazoate

We obtained 434 isolates of Fusarium fujikuroi Nirenberg collected from Hyogo Prefecture and examined their sensitivity to pefurazoate (Pf) and ipconazole (Ip). The minimum inhibitory concentration range profiles in sensitivity to Pf and Ip were from 0.78 μg/mL to 12.5 μg/mL and from 0.39 μg/mL to 1.57 μg/mL, respectively. The efficacy of seed treatment with Pf and Ip against rice Bakanae disease was evaluated using a seedling test with inoculated seeds. The treatment with the mixture of Pf, fludioxonil, and copper oxychloride, and the mixture of Ip-copper hydroxide flowable, showed high efficacy (protective values were larger than 96.0). In contrast, the treatment with the emulsion of Pf showed low efficacy (protective values were less than 90.0) in 7 out of 12 isolates. These results indicated that the sensitivity of some F. fujikuroi isolates to Pf decreased in the Hyogo Prefecture.

Molecular Diagnosis of Thiophanate-Methyl-Resistant Strains of Fusarium fujikuroi in Japan.

Fusarium fujikuroi is the pathogen of rice bakanae disease and is subclassified into gibberellin and fumonisin groups (G and F groups). Thiophanate-methyl (TM), a benzimidazole fungicide, has been used extensively to control F. fujikuroi. Previous investigation showed that F-group strains are TM sensitive (TMS), whereas most G-group strains are TM resistant (TMR) in Japan. The minimum inhibitory concentration in TMS strains was 1 to 10 μg ml-1, whereas that in TMR strains was >100 μg ml-1. E198K and F200Y mutations in β2-tubulin were detected in TMR strains. A loop-mediated isothermal amplification-fluorescent loop primer method was developed for diagnosis of these mutations and applied to 37 TMR strains and 56 TMS strains. The results indicated that 100% of TMR strains were identified as having either the E198K mutation (41%) or the F200Y mutation (59%), whereas none of the TMS strains tested showed either mutation. We found one remarkable TMR strain in the F group that had an F200Y mutation. These results suggest that E198K and F200Y mutations in β2-tubulin contribute to TM resistance in F. fujikuroi.

Characterization of Prochloraz Resistance in Fusarium fujikuroi from Heilongjiang Province in China.

Prochloraz is widely used to control rice bakanae disease caused by Fusarium fujikuroi. The current study was aimed at monitoring the development of F. fujikuroi resistance to prochloraz in the Heilongjiang Province and analyzing the fitness of F. fujikuroi strains with different resistance levels. The results indicated that most of the 89 F. fujikuroi strains collected from the Heilongjiang Province were resistant to prochloraz, with resistance frequency reaching 92.1%. To assess the field resistance risk of prochloraz, 21 F. fujikuroi strains with different resistance levels were selected to investigate their biological characteristics and assess their fitness. Mycelial growth, sporulation, and germination rates were significantly different among the tested strains. However, when grouped into two subpopulations, no significant difference was tested between prochloraz-resistant and prochloraz-sensitive strains. Pathogenicity assays revealed that the disease severity index of prochloraz-resistant strains was higher than that of prochloraz-sensitive strains. Cross-resistance assays showed no cross-resistance between prochloraz and five other fungicides, namely phenamacril, ipconazole, tebuconazole, carbendazim, and fluopyram. Ffcyp51A gene overexpression was observed in the prochloraz-resistant F. fujikuroi strains after exposure to prochloraz. Collectively, these results indicated that F. fujikuroi resistance against prochloraz was severe. Furthermore, prochloraz-resistant strains were highly fit and could potentially become a dominant population in rice fields, consequently resulting in yield loss.

Antibody Generation and Rapid Immunochromatography Using Time-Resolved Fluorescence Microspheres for Propiconazole: Fungicide Abused as Growth Regulator in Vegetable.

Propiconazole (PCZ) is a fungicide popularly used to prevent and control wheat and rice bakanae disease, etc. However, it was recently found to be illegally employed as a plant regulator to induce thick stems and dark green leaves of Brassica campestris, a famous vegetable in Guangdong, South China. Due to a lack of available recognition molecules to the target analyte, it is still a big challenge to establish a rapid surveillance screening method. In this study, a novel chiral hapten was rationally designed, and an artificial immunogen was then prepared for the generation of a specific antibody against propiconazole for the first time. Using the obtained antibody, a highly sensitive time-resolved fluorescence microspheres lateral flow immunochromatographic assay (TRFMs-LFIA) was established with a visual limit of detection of 100 ng/mL and a quantitative limit of detection of 1.92 ng/mL for propiconazole. TRFMs-LFIA also exhibited good recoveries ranging from 78.6% to 110.7% with coefficients of variation below 16%. The analysis of blind real-life samples showed a good agreement with results obtained using HPLC-MS/MS. Therefore, the proposed method could be used as an ideal screening surveillance tool for the detection of propiconazole in vegetables.

Decreased Susceptibility of Rice Bakanae Disease Pathogen to Prochloraz Fungicides in Fukushima

Decreased Susceptibility of Rice Bakanae Disease Pathogen to Prochloraz Fungicides in Fukushima

Rice-associated antagonistic bacteria suppress the Fusarium fujikoroi causing rice bakanae disease

Rice-associated antagonistic bacteria suppress the Fusarium fujikoroi causing rice bakanae disease

Activity of A Novel Succinate Dehydrogenase Inhibitor Fungicide Pydiflumetofen Against Fusarium fujikuroi causing Rice Bakanae Disease.

New fungicides are tools to manage fungal diseases and overcome emerging resistance in fungal pathogens. In this study, a total of 121 Fusarium fujikuroi isolates were collected from various geographical regions of China and their sensitivity to a novel succinate dehydrogenase inhibitor (SDHI) fungicide 'pydiflumetofen' was evaluated. The 50% effective concentration (EC50) value of pydiflumetofen for mycelial growth suppression ranged from 0.0101 to 0.1012 μg/ml and for conidial germination inhibition ranged from 0.0051 to 0.1082 μg/ml. Pydiflumetofen-treated hyphae showed contortion and increased branching, cell membrane permeability, and glycerol content significantly. The result of electron microscope transmission indicated that pydiflumetofen damaged the mycelial cell wall and the cell membrane, and almost broke up the cells, which increased the intracellular plasma leakage. There was no cross-resistance between pydiflumetofen and the widely used fungicides such as carbendazim, prochloraz, and phenamacril. Pydiflumetofen was found safe to seeds and rice seedlings of four rice cultivars, used up to 400 μg/ml. Seed treatment significantly decreased the rate of diseased plants in the greenhouse as well as in field trials in 2017 and 2018. Pydiflumetofen showed superb results against the rice bakanae disease (RBD), when used at 10 or 20 g a.i./100 kg of treated seeds, providing over 90% control efficacy (the maximum control efficacy was up to 97%), which was significantly higher than that of 25% phenamacril (SC) at 10 g or carbendazim at 100 g. Pydiflumetofen is highly effective against F. fujikuroi growth and sporulation as well as RBD in the field.

Sequencing of non-virulent strains of Fusarium fujikuroi reveals genes putatively involved in bakanae disease of rice

Bakanae, one of the most important diseases of rice, is caused by the fungal pathogen Fusarium fujikuroi. The elongation of internodes is the most common symptom induced by the pathogen, and it is related to the production of gibberellins. Despite this, the pathogenicity mechanism of F. fujikuroi is still not completely clear, and there are some strains inducing stunting instead of elongation. Even if there are relatively many genomes of F. fujikuroi strains available in online databases, none of them belongs to an isolate of proven non-virulence, and therefore there has been no comparative genomics study conducted between virulent and non-virulent strains. In the present work, the genomes of non-virulent strain SG4 and scarcely virulent strain C2S were compared to the ones of 12 available virulent isolates. Genes present in the majority of available virulent strains, but not in the non-virulent one, underwent functional annotation with multiple tools, and their expression level during rice infection was checked using pre-existing data. Nine genes putatively related to pathogenicity in F. fujikuroi were identified throughout comparative and functional analyses. Among these, many are involved in the degradation of plant cell wall, which is poorly studied in F. fujikuroi-rice interactions. Three of them were validated through qPCR, showing higher expression in the virulent strain and low to no expression in the low virulent and non virulent strains during rice infection. This work helps to clarify the mechanisms of pathogenicity of F. fujikuroi on rice.

Estimation of yield loss and relationship of weather parameters on incidence of bakanae disease in rice varieties under shallow low land ecologies of Eastern India

Aim: To assess yield loss in different rice varieties due to rice bakanae disease and to understand the role of weather parameters on disease incidence and losses. Methodology: Roving survey and surveillance was carried out for three consecutive years to assess the status of rice bakanae disease among twenty popular rice varieties growing in Eastern India. Field experiment was conducted for three successive years, i.e., 2016, 2017 and 2018 at Cuttack. Highly susceptible variety Pooja was selected for the experiment. Data on disease incidence was collected daily from 10 days after transplanting to harvesting stage and data were recorded at standard meteorological week. Correlation was performed to find the effect of different weather parameters on the incidence of bakanae disease on rice. Results: Disease being seed borne caused significant reduction in yield and quality. The maximum disease incidence was recorded in Pooja with 18.25, 28.50 and 40.25 per cent in three years. The same variety showed maximum yield loss of 35.26 per cent compared all other varieties. The data on relationship of bakanae disease incidence with weather parameters showed that the rainfall (-0.444) had significant negative correlation during 2018, while RH (0.525 and 0.606) had significant positive correlation during 2017 and 2018. Interpretation: This study gives some information for formulating breeding programs to develop resistant varieties and management measures for preventing Bakanae disease.

Efficacy of a novel succinate dehydrogenase inhibitor pydiflumetofen to control rice bakanae disease caused by Fusarium fujikuroi

Efficacy of a novel succinate dehydrogenase inhibitor pydiflumetofen to control rice bakanae disease caused by Fusarium fujikuroi

Molecular phylogeny, pathogenic variability and phytohormone production of Fusarium species associated with bakanae disease of rice in temperate agro-ecosystems

Bakanae is the emerging disease threating the rice cultivation globally. Yield reduction of 4-70% is recorded in different parts of the world. A total of 119 Fusarium isolates were collected from rice plants at different geographical locations and seeds of different rice cultivars. The isolates were evaluated for morphological, biochemical and pathogenic diversity. The amplification of TEF-1α gene was carried out for exploring the species spectrum associated with the cultivated and pre-released rice varieties. The production of gibberellin varied from 0.53 to 2.26µg/25ml, while as that of Indole acetic acid varied from 0.60 to 3.15µg/25ml among the Fusarium isolates. The phylogenetic analysis identified 5 different species of the genus Fusarium viz. Fusarium fujikuroi, F. proliferatum, F. equiseti, F.oxysporum and F. persicinum after nucleotide blasting in NCBI. Only two Fusarium spp. F. fujikuroi and F. proliferatum were found to be pathogenic under virulence assays of the isolates. The isolates showed a considerable variation in morphological and pathogenic characters. The isolates were divided into different groups based on morphology and pathogenicity tests. The isolates showed a considerable variation in morphology, phytohormone profile and virulence indicative of population diversity. Three species F. equiseti, F.oxysporum and F. persicinum which have not been reported as pathogens of rice in India were found to be associated with bakanae disease of rice, however their pathogenicity could not be established.

Rice Bakanae Disease: Yield Loss and Management Issues in Bangladesh

Fusarium moniliforme, a causal agent of rice Bakanae is a seedborne fungal disease which infects plants through the roots or crowns and it then grows systemically within the plant. From the in-vitro and in-vivo results, it was concluded that Bavistin, Knowin, Haydazim, Topsil plus and Sunphanate @ 0.3% could be effective as seed treating fungicides against bakanae disease. Overnight root dipping of seedlings with Bavistin and Knowin @ 0.3% was effective to control bakanae disease. Seed and seedling treatments with carbendazim fungicides could be used for further dissemination. In field trials, none of the fungicides namely Bavistin, Knowin, Ridomil, Forastin, Sunphanate and Cupravit @ 0.3% were effective against bakanae compared to rogueing when those were sprayed in the standing crop at tillering stage. In seedbed condition, wet seed bed reduced the % of bakanae infected hill (0.31%) in comparison with semi dry (2.18%) and dry (3.45%). In combination with seed bed conditions and seed treatments, wet seed bed with healthy or infected seed but treated with homai @ 0.3% reduced the bakanae incidence (0.21-0.39%). Semi dry seed bed with healthy or infected seed but treated with homai @ 0.3% also control the bakanae disease (0.32-2.68%) compared to dry seed bed (0.82-2.7%).

Mapping of a Major QTL, qBK1Z, for Bakanae Disease Resistance in Rice.

Bakanae disease is a fungal disease of rice (Oryza sativa L.) caused by the pathogen Gibberella fujikuroi (also known as Fusarium fujikuroi). This study was carried out to identify novel quantitative trait loci (QTLs) from an indica variety Zenith. We performed a QTL mapping using 180 F2:9 recombinant inbred lines (RILs) derived from a cross between the resistant variety, Zenith, and the susceptible variety, Ilpum. A primary QTL study using the genotypes and phenotypes of the RILs indicated that the locus qBK1z conferring bakanae disease resistance from the Zenith was located in a 2.8 Mb region bordered by the two RM (Rice Microsatellite) markers, RM1331 and RM3530 on chromosome 1. The log of odds (LOD) score of qBK1z was 13.43, accounting for 30.9% of the total phenotypic variation. A finer localization of qBK1z was delimited at an approximate 730 kb interval in the physical map between Chr01_1435908 (1.43 Mbp) and RM10116 (2.16 Mbp). Introducing qBK1z or pyramiding with other previously identified QTLs could provide effective genetic control of bakanae disease in rice.

Combined and single effects of elevated CO2 and temperatures on rice bakanae disease under controlled conditions in phytotrons

AbstractBakanae disease, caused by Fusarium fujikuroi, was investigated under different CO2 and temperature environments in order to simulate climate changes in the F. fujikuroi–rice pathosystem. F. fujikuroi‐infected plants were grown under six phytotron conditions: low (18/22 °C night/day), medium (22/26 °C), and high (26/30 °C) temperature, at either ambient (450 ppm) or elevated (850 ppm) CO2 concentrations. Bakanae disease index (DI), seedling death incidence, fungal DNA quantity, and chlorophyll and carbohydrate contents varied significantly in infected plants as a consequence of changes in both CO2 and temperature. Plant height and dry weight were only influenced by single factors (temperature for height, and temperature or CO2 for dry weight), and not by the CO2 × temperature interaction. Medium and high temperatures (irrespective of the CO2 level) increased the DI significantly (range from 67.5% to 95.8%) compared to low temperatures (range from 45.8% to 47.5%). Under elevated CO2 levels, noticeable differences in the expression of four rice defence‐related genes and fungal DNA quantity were observed between those plants grown at higher temperatures and those at lower temperatures. Overall, combined and single effects of elevated CO2 and high temperatures seem to be favourable for bakanae disease development in the Mediterranean basin.

Rice bakanae disease: an emerging threat to rice production in Bangladesh

Bakanae disease has been reported from almost all the rice growing countries in the world. The disease has been emerged as a major problem in some of the Asian countries including Bangladesh. Bakanae is becoming a serious threat to sustainable rice production in Bangladesh particularly in the northeastern part of the country and accounted for causing up to 25% yield losses. The disease has become difficult to manage due to lacking appropriate disease diagnosis. Fusarium fujikuroi mainly caused this disease but other Fusarium species are also reported to be involved for causing this disease. It, therefore, is crucial to understand the association of Fusarium species with Bakanae disease for sustainable rice disease management in Bangladesh.
 Asian J. Med. Biol. Res. December 2020, 6(4): 608-610

Identification of Rice Seed-Derived Fusarium spp. and Development of LAMP Assay against Fusarium fujikuroi

Fusarium species are important seedborne pathogens that cause rice bakanae disease (RBD). In this study, 421 strains were isolated from 25 rice samples collected from Zhejiang, Anhui, and Jiangxi provinces of China. Furthermore, 407 isolates were identified as F. fujikuroi (80.05% isolation frequency), F. proliferatum (8.31%), F. equiseti (5.94%), F. incarnatum (2.61%), F. andiyazi (0.95%), and F. asiaticum (0.48%) based on morphology and translation elongation factor 1-alpha (TEF1-α) gene. Phylogenetic analysis of combined sequences of the RNA polymerase II largest subunit (RPB1), RNA polymerase II second largest subunit (RPB2), TEF1-α gene, and ribosomal DNA (rDNA) internal transcribed spacer (ITS) showed that 17 representative strains were attributed to six species. Pathogenicity tests showed that representative isolates possessed varying ability to cause symptoms of bakanae on rice seedlings. Moreover, the seed germination assay revealed that six isolates had different effects, such as inhibition of seed germination, as well as seed and bud rot. The loop mediated isothermal amplification (LAMP)-based assay were developed for the detection of F. fujikuroi. According to sequences of desaturase-coding gene promoter, a species-specific marker desM231 was developed for the detection of F. fujikuroi. The LAMP assay using seeds collected from field was validated, and diagnostics developed are efficient, rapid, and sensitive.

Expression difference of P450–1 and P450–4 between G- and F-groups of Fusarium fujikuroi

Fusarium fujikuroi is the pathogen of rice bakanae disease and has been intensively studied for gibberellin (GA) production. F. fujikuroi is phylogenetically subclassified into G- and F-groups, which differ in GA and fumonisin production. A higher amount of GA is produced by the G-group than the F-group. A previous study found that the GA production difference between the G-group strain Gfc0801001 and the F-group strain Gfc0825009 was due to the GA gene cluster. In this study, higher expression of P450–1 and P450–4 in the GA gene cluster were detected in G-group strains than in F-group strains. The nucleotide sequence of the bidirectional promoter region between P450–1 and P450–4 and expression of P450–1 and P450–4 were compared between G- and F-group strains. The promoter sequence was identical among G-group strains while nucleotide substitutions were detected at various locations in F-group strains. Most F-group strains did not share the same substitutions. These results combined with the ancestral position of the F-group in the phylogenetic tree suggest that the population carrying highly expressed sequence generates the G-group rather than the low expression of P450–1 and P450–4 in the F-group due to a specific mutation occured in G-group.

Invasion and Colonization Pattern of Fusarium fujikuroi in Rice.

Bakanae disease in rice can cause abnormal elongation of the stem and leaves, development of adventitious roots, a larger leaf angle, and even death. Little is known about the infection, colonization, and distribution of Fusarium fujikuroi in rice plants across different growth stages. In this study, microscopic observation and quantitative real-time PCR were combined to investigate the pathogenesis of bakanae, using artificially inoculated seedlings of a susceptible rice cultivar, Zerawchanica karatals (ZK), a resistant cultivar, Tainung 67 (TNG67), naturally infected adult field plants (cultivars Kaohsiung 139, Taikeng 2, and Tainan 11), and an F. fujikuroi isolate expressing green fluorescent protein. In rice seedlings, F. fujikuroi hyphae were found to directly penetrate the epidermis of basal stems and roots, then extend inter- and intracellularly to invade the vascular bundles. Occlusion of vascular bundles and radial hyphal expansion from vascular bundles to surrounding parenchyma were observed in adult plants. Analysis of consecutive 3-cm segments of the whole plant revealed that F. fujikuroi was largely confined to the embryo, basal stem, and basal roots in seedlings, and distributed unevenly in the lower aerial parts (including nodes and internodes) of adult plants. The elongation and development of adventitious roots did not necessarily correlate with the amount of F. fujikuroi in diseased plants. Treatment of rice seeds with gibberellic acid-3 (GA3) at 0.5 mg/liter resulted in significantly more elongation of ZK than TNG67 seedlings, suggesting that the susceptibility of ZK to bakanae is associated with its higher sensitivity to GA3.