Screening and evaluation of the biocontrol efficacy of a Trichoderma brevicompactum strain and its metabolite trichodermin against banana Fusarium wilt / 生物工程学报

The banana Fusarium wilt (BFW) caused by Fusarium oxysporum f. sp. cubense tropical race4 (FocTR4) is difficult to control worldwide, which causes a huge economic losse to banana industry. The purpose of this study was to screen Trichoderma strains with antagonistic activity against FocTR4, to isolate and purify the active compound from the fermentation broth, so as to provide important biocontrol strains and active compound resources. In this work, Trichoderma strains were isolated and screened from the rhizosphere soil of crops, and the strains capable of efficiently inhibiting FocTR4 were screened by plate confrontation, and further confirmed by testing inhibition for the conidial germination and mycelial growth of FocTR4. The phylogenetic tree clarified the taxonomic status of the biocontrol strains. Moreover, the active components in the fermentation broth of the strains were separated and purified by column chromatography, the structure of the most active component was analyzed by nuclear magnetic resonance spectroscopy (NMR), the BFW control effect was tested by pot experiments. We obtained a strain JSHA-CD-1003 with antagonistic activity against FocTR4, and the inhibition rate from plate confrontation was 60.6%. The fermentation broth of JSHA-CD-1003 completely inhibited the germination of FocTR4 conidia within 24 hours. The inhibition rate of FocTR4 hyphae growth was 52.6% within 7 d. A phylogenetic tree was constructed based on the ITS and tef1-α gene tandem sequences, and JSHA-CD-1003 was identified as Trichoderma brevicompactum. Purification and NMR identification showed that the single active compound was trichodermin, and the minimum inhibitory concentration (MIC) was 25 μg/mL. Pot experiments showed that the fermentation broth of strain JSHA-CD-1003 was effective against BFW. The control rate of leaf yellowing was 47.4%, and the rate of bulb browning was 52.0%. Therefore, JSHA-CD-1003 effectively inhibited FocTR4 conidial germination and mycelium growth through producing trichodermin, and showed biocontrol effect on banana wilt caused by FocTR4, thus is a potential biocontrol strain.

Exploring Novel Sources of Resistance to Cercospora Leaf Spot and Fusarium Wilt Diseases in Cotton

Identify the sources of resistance to Cercospora leaf spot and Fusarium wilt diseases in Cotton under natural field conditions with artificial inoculation at Regional Agricultural Research Station, Warangal of the Telangana State in India. The experimental material consisted of Fifty two cotton germplasms and 13 Bt cotton hybrids with a check. They were tested against Cercospora leaf spot and Fusarium wilt diseases during Kharif 2016. Out of 52 cotton germplasms,14 entries viz.,HYPS-152,H-1250,SA-434,KH-2244N,KH-134,MRK-38,LH-2170,AKH-2822,LH-900,JK-2764,NH-615, GBHU-164,RAH-100 and HOC-5 were found resistant to Cercospora leaf spot and nine entries namely MCU-13, HYPS-152, H-1250, RAH-4, RCH-2, JK-2764, CCH1071, SCS-101, CCH-11 were found resistant to Fusarium wilt disease.Out of screened 13 Bt cotton hybrids, one entry Ankur-3224 was found resistant to Cercospora leaf spot disease and three entries namely First class, Ankur-3224 and RCH-812 were found moderately resistant to Fusarium wilt disease.

Occurrence and Distribution of Lentil Wilt in Major Lentil Growing Regions of Madhya Pradesh, India

In the present investigation, roving survey was conducted during the October to February of 2020–2021 and 2021–22 to acquire information on the natural disease incidence and distribution of lentil wilt in the farmers’ fields in eight different districts of Madhya Pradesh. A pooled mean of disease incidence ranging from 6.62%–20.36% was observed during 2020–22. The district wise scenario of lentil wilt over a period of two consecutive years revealed that maximum average incidence of 18.96% was recorded in Sagar district followed by 17.67% in Khandwa district. However, minimum average wilt incidence of 12.17% was recorded in Mandla district followed by 12.55% in Jabalpur district. Looking to the occurrence of lentil wilt, Sagar, Khandwa, Damoh, Katni and Dindori were identified as hotspot pockets for occurrence of lentil wilt in surveyed districts of Madhya Pradesh. Further, reduction of 26.28% in wilt occurrence was recorded in the farmers’ practice advocated as seed treatment before sowing. Under the seven cropping patterns observed, the minimum wilt incidence of 13.96% was recorded in rice followed by lentil which is the most predominant cropping pattern across the surveyed locations. Further different varieties were screened for occurrence of lentil wilt at Sagar. Among the 14 varieties, maximum incidence of lentil wilt was recorded in PL 5 followed by Shekhar masoor 3. However, two varieties namely JL 1 and L 4076 were found free from wilt incidence in selected hot spot pocket for lentil wilt.

Identifying F. oxysporum Strains Causing Wilt in Southern Indian Chickpeas

Fusarium oxysporum (Schletend: Fr) f. sp. ciceri (Padwick), referred to as Foc, is a soil-borne fungus that poses a constant threat to chickpeas (Cicer arietinum L.) by causing wilt disease. Typical wilt symptoms were observed in chickpea plants collected from 24 different locations across three southern Indian states. The process involved isolating Fusarium species from the roots of these wilted plants, resulting in the identification of various strains exhibiting diverse cultural and morphological characteristics on potato dextrose agar medium. All twenty four isolates were subjected to Koch's postulates using the standard method, which yielded varied responses in terms of disease incidence. After analyzing cultural, morphological, molecular traits, and conducting pathogenicity tests, the fungus was definitively identified as F. oxysporum Schlechtend. Fr. f. sp. ciceri (Padwick) Matuo and K. Sato. Among the 24 isolates tested on the chickpea wilt susceptible cultivar JG-62, one was non-pathogenic with zero percent disease incidence (PDI), while one isolate was highly pathogenic showed 100 percent PDI. Highly pathogenic four isolate was further used for molecular identification with secreted in xylem primers (SIX). Comparative studies of cultural traits and conidial morphology among different isolates revealed variations in growth patterns, pigmentation, sporulation, and the size and structure of macro and micro conidia, as well as chlamydospores.

Screening of marine resistant strain based on PKS and NRPS genes and the activity of its metabolites / 生物工程学报

Based on polyketide syntheses gene (PKS) and non-ribosomal peptide synthetases gene (NRPS), one strain with high anti-pathogenic activity was screened from 77 strains isolated from Arctic marine sediments and identified. By optimizing the composition of culture medium and fermentation conditions, the production of this strain's active metabolites was improved and the main metabolites were identified by HRMS, 1H NMR and 13C NMR. The antibacterial spectrum of the main metabolites and the effect of the metabolites on cucumber Fusarium wilt were also determined. The results showed that the strain was Bacillus velezensis and it showed growth promoting effect on plants. When the strain was cultured in 5 g/L maltose, 10 g/L tryptone, 10 g/L sodium chloride, at 30 ℃, 150 r/min for 60 h, the diameter of the inhibition zone increased from (16.23±0.42) to (24.42±0.57) mm. The metabolites of this strain mainly contain macrolide compound macrolactin A, which has antagonistic effect on a variety of pathogenic bacteria and fungi. Cucumber seedling experiments showed that the metabolites of this strain had a protective effect on cucumber Fusarium wilt, and showed a good potential for development and application as a biocontrol agent.

Fusarium Wilt Changes Microbial Community Structure in Rhizosphere Soil of Chrysanthemum morifolium / 中国实验方剂学杂志

Objective:To explore the differences in rhizosphere microbial community structure between <italic>Fusarium</italic> wilt-infected and healthy <italic>Chrysanthemum morifolium </italic>plants<italic>.</italic> Method:The rhizosphere soils of diseased and healthy<italic> C. morifolium </italic>plants were sampled and subjected to high-throughput 16S ribosomal DNA （rDNA） and internal transcribed spacer （ITS） sequencing， to identify the microbial community structure including bacteria and fungi. Result:<italic>Fusarium</italic> wilt reduced the bacterial abundance and diversity but had no significant effect on fungal alpha-diversity.The proportions of Acidobacteria， Gemmatimonadetes， and Nitrospirae in rhizosphere soil of healthy <italic>C.morifolium</italic> plants were higher than those of diseased plants， while the proportions of Proteobacteria and Bacteroidetes were lower（<italic>P</italic><0.05）. <italic>Fusarium</italic> fungi accounted for 27.49%， 14.53%， and 11.94% in diseased plants whereas 0.47%， 1.01%， and 0.67% in healthy plants.Pathogenic bacteria <italic>Pectobacterium</italic> and <italic>Dickeya</italic> were enriched in rhizosphere soil of diseased plants. The abundances of nitrifying， detoxifying， and photosynthetic bacteria in rhizosphere soil of healthy plants were higher than those of diseased plants. Conclusion:<italic>Fusarium</italic> wilt reduces the bacterial richness and diversity and triggers the enrichment of massive <italic>Fusarium</italic> fungi， <italic>Pectobacterium</italic>， and <italic>Dickeya</italic>. The proportion of beneficial bacteria in rhizosphere soil of healthy plants is significantly higher than that of diseased plants.

Morphological and molecular characterization of Fusarium spp. associated with Fusarium wilt disease of Piper nigrum L. in Northwestern region of Sarawak

Aims@#Piper nigrum L. (black pepper) is an economically important commodity plant in Malaysia, which generated RM 200.95 million from pepper export in the year of 2018. However, the increase in pepper production is restricted by diseases. Fusarium wilt is one of the major diseases of P. nigrum L. The objectives for this study were to isolate Fusarium spp. associated with Fusarium wilt of P. nigrum L. from selected pepper farms in the northwestern region of Sarawak and to characterize the Fusarium spp. isolated morphologically and molecularly.@*Methodology and results@#Fusarium spp. were isolated from diseased root samples. The pathogen was grown on potato dextrose agar (PDA) under dark condition at circa (ca.) 25 °C for morphological characterisation. Molecular characterisation was done by using internal transcribed spacer (ITS). Phylogenetic tree was constructed to study the genetic relationship of the isolates. Fusarium solani, F. oxysporum, F. proliferatum were the three Fusarium species identified. There were variations in morphological characters observed between and among the species, including the colony form, margin, elevation, surface appearance and pigmentation. No distinctive morphological characteristic was specific to a location. In addition, growth rate, macroconidia sporulation rate, and microconidia sporulation rate of the isolates were not correlated. In molecular phylogeny, the three Fusarium species were separated into three distinct clades representing the three identified species. The genetic relatedness between isolates within each species was depicted in the tree. @*Conclusion, significance and impact of study@#Variations were observed among isolates in this study based on morphological and molecular characterization. This study would contribute information on the variations of Fusarium spp. associated with Fusarium wilt of P. nigrum L. from the northwestern region of Sarawak.

Action of Trichodermil 1306 in the control of Fusarium oxysporum f. sp. lycopersici in tomato crops / Ação do Trichodermil 1306 no controle de Fusarium oxysporum f. sp. lycopersici na cultura do tomateiro

Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici, is one of the most important diseases of tomato crop in Brazil. Several alternatives to fungicides have been evaluated in search for products that control this disease and have low environmental impact and toxicity to living beings. In this context, the use of Trichoderma spp. is an alternative to agrochemicals, since they are bioregulators and antagonists of several phytopathogens. This work aimed to evaluate the antagonistic and mycoparasitory action of the Trichodermil 1306 biofungicide against F. oxysporum, and its action in the control of fusarium wilt in tomato seeds and seedlings. The biofungicide was used at concentrations of 0, 50, 100, and 150% of the dose recommended for application of 20 L with a backpack sprayer. The experiment was conducted in a completely randomized design with five replications. Data were submitted to analysis of variance and mean compared by Tukey's test at 5% probability. The 100% Trichodermil concentration was the most efficient for treating tomato seeds. Although this concentration did not show differences in relation to the lowest dose used (50%) in the tomato seed antagonism, mycoparasitism and F. oxysporum incidence tests were recommended because that the lowest concentration resulted in 18% lower root protrusion than that observed with 100% dosage. The in vitro antagonistic and mycoparasitory action of this biological fungicide indicates its potential in the control of fusarium wilt in tomato crops.(AU)

A murcha-de-fusário, causada por Fusarium oxysporum f. sp. lycopersici, é uma das mais importantes doenças da cultura do tomate no Brasil. Várias alternativas aos fungicidas têm sido avaliadas na busca de produtos que controlem a doença e tenham baixo impacto ambiental e toxicidade aos seres vivos. Nesse contexto, o uso de Trichoderma spp. é uma alternativa a agrotóxicos, pois são biorreguladores e antagonistas de vários fitopatógenos. O objetivo do trabalho foi avaliar a ação antagonista e micoparasitória do biofungicida Trichodermil 1306 em F. oxysporum, e no controle da murcha-de-fusário em sementes e mudas de tomate. O biofungicida foi utilizado nas concentrações de 0, 50, 100 e 150% da dose recomendada para aplicação com pulverizador costal de 20 L. O experimento foi conduzido em delineamento inteiramente casualizado, com cinco repetições. Os dados foram submetidos à análise de variância e as médias foram comparadas pelo teste de Tukey a 5% de probabilidade. A concentração de Trichodermil 100% foi a mais eficaz para o tratamento de sementes de tomateiro. Embora essa concentração não tenha se diferenciado da menor dosagem utilizada (50%) para os testes de antagonismo, micoparasitismo e incidência de F. oxysporum em mudas de tomate, sua recomendação se justifica pelo fato da menor concentração ter propiciado protrusão radicular 18% menor do que a observada na concentração de 100%. A ação antagonista e micoparasitória in vitro do fungicida biológico testado no presente estudo indica potencialidade de uso para o controle de murcha-de-fusário em tomateiro.(AU)

Inoculation methods and aggressiveness of five Fusarium species against peach palm / Métodos de inoculação e agressividade de cinco espécies de Fusarium à pupunheira

ABSTRACT: Fusarium wilt is a major disease which affects peach palm (Bactris gasipaes Kunth.var gasipaes Henderson). This study aimed to evaluate inoculation methods and aggressiveness of isolates of five Fusarium species on peach palm. Fusarium proliferatum can infect the leaves, stem, and roots of peach palm. F. proliferatum, F. oxysporum species complex (FOSC), F. verticillioides, F. solani species complex (FSSC), and Gibberella fujikuroi species complex (GFSC) are pathogenic to peach palm. The use of Fusarium-colonized ground corn for root inoculation was effective and reduced the level of damage to plants.

RESUMO: A fusariose é uma das principais doenças da pupunheira (Bactris gasipaes Kunth.var gasipaes Henderson). O objetivo deste trabalho foi avaliar métodos de inoculação e a agressividade de isolados de cinco espécies de Fusarium à pupunheira. Demonstrou-se que Fusarium proliferatum pode infectar folhas, caule e raízes de pupunheira. Verificou-se que as espécies F. proliferatum, F. oxysporum species complex (FOSC), F. verticillioides, F. solani species complex (FSSC) e Gibberella. fujikuroi species complex (GFSC) são patogênicas à pupunheira e, que o uso da quirera colonizada por Fusarium para inoculação de raízes foi efetivo e reduziu o nível de injúrias às plantas.

Evaluation of different banana genotypes for resistance to panama disease / Avaliacao de diferentes genótipos de bananeira quanto a resistencia ao mal-do-panamá

Panama disease, or fusarium wilt disease, caused by the fungus Fusarium oxysporum f.sp. cubense is a disease causing great losses in banana production worldwide, hindering production in certain areas of the world. In Brazil, banana crop has suffered great losses due to favorable soil and climate conditions for the development of pests and diseases and, also, by the low technological level used in most growing areas of the country. Therefore, the use of genetic resistance for the control of this disease becomes a promising alternative, making possible the cultivation of bananas in some areas that had been decimated by this pathogen. Thus, this study evaluated the performance of banana genotypes subjected to artificial inoculation with F. oxysporum f.sp. cubense in a nursery and in the field. The genotypes Tropical, Pacovan, Caipira, Japira, Princesa and Fhia-18, besides 'Prata Anã', as a susceptible control, were evaluated in a completely randomized design, with 4 replications, and each replication consisted of two plants. The seedling were also subjected to a field test in a completely randomized design, with three replications. Disease severity, for external symptoms, was evaluated 50 days after inoculation, using a rating scale in which, all plants, except for Fhia-18, which did not show symptoms, had initial yellowing of older leaves. Field evaluations consisted of measuring plant height and diameter, and after harvesting the banana bunches, internal symptoms were observed in the pseudostems. Cultivars Prata- Anã and Caipira had greater susceptibility to the disease.

Alguns problemas da bananicultura mundial se tornaram também problemas para o Brasil. A doença fúngica de solo, que limita o cultivo da banana 'Maçã' é de difícil controle e tornou-se grave problema em algumas importantes áreas de cultivo é o mal-do-Panamá, uma das mais importantes doenças da bananeira, causada pelo fungo Fusarium oxysporum f.sp. cubense, provoca elevadas perdas na produção e pode persistir no solo por muitos anos. Portanto o objetivo desse trabalho é avaliar o comportamento de genótipos de bananeira quando submetidos à inoculação artificial de Fusarium oxysporum f.sp. cubense em situação de viveiro de mudas e situação de campo. Foram avaliados os genótipos Tropical, Pacovan, Caipira, Japira, Princesa e Fhia-18, além da 'Prata Anã' como testemunha (suscetível), em delineamento inteiramente casualizado, com 4 repetições, sendo duas plantas por repetição. As mudas também foram submetidas a teste de campo em que o delineamento experimental foi inteiramente casualizado com 3 repetições. A severidade da doença quanto aos sintomas externos foi avaliada aos 50 dias após a inoculação utilizando escala de notas, na qual todas as plantas, com exceção da Fhia-18 que não apresentou sintomas, apresentaram amarelecimento inicial nas folhas velhas.No teste de campo foram avaliados, altura e diâmetro das plantas e após a retirada dos cachos, foi observado os sintomas internos do pseudocaule onde as cultivares Prata-Anã e Caipira apresentaram maior suscetibilidade a doença.

First Report on Fusarium Wilt of Zucchini Caused by Fusarium oxysporum, in Korea

Fusarium wilt of zucchini in Jeonju, Korea, was first noticed in May 2013. Symptoms included wilting of the foliage, drying and withering of older leaves, and stunting of plants. Infected plants eventually died during growth. Based on morphological characteristics and phylogenetic analyses of the molecular markers (internal transcribed spacer rDNA and translation elongation factor 1alpha), the fungus was identified as Fusarium oxysporum. Pathogenicity of a representative isolate was demonstrated via artificial inoculation, and it satisfied Koch's postulates. To our knowledge, this is the first report of F. oxysporum causing wilt of zucchini in Korea.

Construction of cDNA expression library of watermelon for isolation of ClWRKY1 transcription factors gene involved in resistance to Fusarium wilt.

Full-length cDNAs are very important for genome annotation and functional analysis of genes. The number of full-length cDNAs from watermelon remains limited. Here we report first the construction of a full-length enriched cDNA library from Fusarium wilt stressed watermelon (Citrullus lanatus Thunb.) cultivar PI296341 root tissues using the SMART method. The titer of primary cDNA library and amplified library was 2.21 × 106 and 2.0 × 1010 pfu/ml, respectively and the rate of recombinant was above 85%. The size of insert fragment ranged from 0.3 to 2.0 kb. In this study, we first cloned a gene named ClWRKY1, which was 1981 bp long and encoded a protein consisting of 394 amino acids. It contained two characteristic WRKY domains and two zinc finger motifs. Quantitative real-time PCR showed that ClWRKY1 expression levels reached maximum level at 12 h after inoculation with Fusarium oxysporum f. sp. niveum. The full-length cDNA library of watermelon root tissues is not only essential for the cloning of genes which are known, but also an initial key for the screening and cloning of new genes that might be involved in resistance to Fusarium wilt.

Raios gama na sobrevivência de plantas de maracujazeiro amarelo inoculadas com Fusarium oxysporum f sp. passiflorae / Gamma rays on the survival of yellow passion fruit inoculated with Fusarium oxysporum f sp. passiflorae

A murcha de Fusarium ou fusariose ocorre em diversas regiões produtoras de maracujá amarelo e tem ocasionado grandes danos devido à morte das plantas. A mutagênese associada à seleção in vitro utilizando fitotoxinas possibilita a aplicação de uma pressão de seleção sobre um grande número de propágulos e, assim, pode direcionar a seleção dos mutantes específicos. Neste trabalho, foi analisado o efeito de raios gama sobre a sobrevivência de plantas de maracujazeiro amarelo inoculados com F. oxysporum f. sp. passiflorae. Brotações foliares provenientes de segmentos caulinares de P. edulis irradiados a 20Gy foram submetidas a dois ciclos de seleção em meio de cultura suplementado com o filtrado da cultura fúngica (40% e 50% de filtrado). As plantas selecionadas foram inoculadas com a suspensão de conídio em casa de vegetação e após, transferidas para o campo em local com histórico da doença. Ao final da etapa de seleção in vitro, sobreviveram 17,05% das plantas irradiadas e nenhuma planta do tratamento testemunha. A inoculação com a suspensão de conídio não resultou em diferenças significativas na sobrevivência das plantas irradiadas e não irradiadas. No entanto, em condições de campo, foi confirmado o efeito da radiação no aumento da sobrevivência das plantas, sendo verificada a sobrevivência de 77,78% das plantas irradiadas e a morte de todas as plantas do tratamento testemunha.

The Fusarium vascular wilt occurs in several passion fruit producing regions and it has been caused hight plant mortality. Mutagenesis associated with in vitro selection using phytotoxins enables the application of a strong selection pressure on a large number of propagules and driving the selection of specific mutants. In this research, it was investigated the effect of gamma rays on the survival of yellow passion fruit plants inoculated with F. oxysporum f. sp. passiflorae. Shoots from stem segments of P. edulis irradiated at 20Gy were subjected to two cycles of selection in culture medium supplemented with a fungal culture filtrate (40% and 50% of filtrate). The selected plants were inoculated with conidia suspension in greenhouse and then transferred to field with a serious incidence of Fusarium wilt. At the end of the in vitro selection stage no control plants and 17.05% of irradiated plants survived. The suspension conidia inoculation resulted in no significant differences in survival for irradiated and non-irradiated plants. However, under field conditions radiation positively affect the plant survival. Of the irradiated plants 77.78% survived and all control plants died.

Reação de linhagens de feijoeiro ao fungo Fusarium oxysporum f. sp. phaseoli em condições controladas / Reaction of common bean lines to Fusarium oxysporum f. sp. phaseoli in controlled conditions

Entre os patógenos que mais contribuem para a redução da produtividade do feijoeiro no Brasil está o Fusarium oxysporum f. sp. phaseoli. O emprego de cultivares resistentes é o controle mais eficaz para esse patógeno. Conduziu-se este trabalho, com o objetivo de avaliar linhagens de feijoeiro (Phaseolus vulgaris L.) do banco de germoplasma da Universidade Federal de Lavras (UFLA), quanto a reação ao Fusarium oxysporum f. sp. phaseoli e, ao mesmo tempo, estimar os parâmetros genéticos e fenotípicos que possam auxiliar em futuros programas de melhoramento para esse caráter. Foram avaliadas 367 linhagens em dez experimentos. As testemunhas 'Carioca' (suscetível) e 'Carioca MG' (resistente) foram utilizadas em todos os experimentos. O delineamento utilizado foi inteiramente ao acaso, com cinco repetições e parcelas de uma planta por vaso. As inoculações foram realizadas segundo a metodologia de corte e imersão de raízes na suspensão de esporos do fungo e as avaliações realizadas aos 21 dias após a inoculação com base no índice de severidade da doença empregando-se notas de 1 (plantas sem sintomas) a 9 (plantas mortas).Das linhagens do banco de germoplasma da Universidade Federal de Lavras (UFLA) avaliadas, 36,5 por cento foram resistentes ao Fusarium oxysporum f. sp. phaseoli. Entre as resistentes, a maioria foi linhagens obtidas antes de 1990. Das 18 linhagens dos experimentos de VCU, do período de 2005/06, apenas quatro foram suscetíveis. A estimativa da herdabilidade (h²) foi elevada (h² = 87 por cento), indicando que, a princípio, o caráter é de fácil seleção.

Among the pathogens that most contribute for reducing the productivity of beans in Brazil is the Fusarium oxysporum f. sp. phaseoli. The use of resistant cultivars is the most effective control for this pathogen. The aim of this study was to evaluate germoplasm bean (Phaseolus vulgaris L.) lines of the Federal University of Lavras (UFLA) as the reaction to the Fusarium oxysporum f. sp. phaseoli and at the same time, to estimate the genetic and phenotypic parameters that could help in future programs of improvement for this character. Three hundred and sixty seven lines were evaluated in ten experiments. The controls' Carioca'(susceptible) and 'Carioca MG'(resistant) were used in all experiments. The experimental design used was a entirely randomized one, with five replicates and plots of one plant per pot. The inoculations were carried out following the method of cutting and dumping of roots in the suspension of spores of the fungus and the assessments conducted at 21 days after inoculation based on the index of severity of the disease employing up notes of 1 (plants without symptoms) to 9 (dead plants). Among the lines of germoplasm bank of the Federal University of Lavras (UFLA) assessed, 36.5 percent were resistant to Fusarium oxysporum f. sp. phaseoli. Among the resistance, most of the lines were obtained before 1990: out of the 18 lines of the experiments of VCU evaluated in 2005/06, only four were susceptible. The estimate of heritability (h²) was high (h² = 87 percent), indicating that, in principle, the character is of easy selection.

Reação de cultivares e linhagens de feijoeiro em relação a Meloidogyne javanica e Fusarium oxysporum f. sp. phaseoli / Reaction of cultivars and lines of bean in relation to Meloidogyne javanica and Fusarium oxysporum f. sp. phaseoli

Os nematoides do gênero Meloidogyne e o fungo do gênero Fusarium sp. podem limitar a produção das culturas. Assim, no presente trabalho, o objetivo foi avaliar o comportamento de nove cultivares e duas linhagens de feijoeiro P. vulgaris ao nematoide M. javanica e ao fungo F. oxysporum f. sp. phaseoli (Fofsp) e a interação destes. Os ensaios foram conduzidos sob condições de casa-de-vegetação, em delineamento estatístico inteiramente ao acaso, com quatro tratamentos com oito repetições na avaliação efetuada aos 35 dias e quatro tratamentos para a avaliação aos 60 dias da inoculação. Na primeira avaliação, foram determinados o número de galhas (NG) para M. javanica, no sistema radicular, e a severidade (SEV), para F. oxysporum f. sp. phaseoli. Na avaliação aos 60 dias, as análises foram idênticas aos da primeira avaliação, porém, determinou-se também o fator de reprodução do nematoide. Nas duas avaliações realizadas, foi observado que M. javanica isoladamente ou em associação com F. oxysporum foi parasita de todas as linhagens e cultivares de feijão testadas. Para F. oxysporum isoladamente, as cultivares 'Pérola' e 'IAPAR 14' e a linhagem LP99-85 comportaram-se como resistentes. Na cultivar 'Pérola', observou-se um aumento significativo da severidade dos sintomas à murcha de Fusarium, quando o fungo estava associado a M. javanica.

The nematode of the genera Meloidogyne and the fungi Fusarium may reduce the crop yield. So, the present paper had as objective to evaluate the behavior of nine cultivars and two lines of bean P. vulgaris to the nematode M. javanica the fungi F. oxysporum f. sp. phaseoli (Fofsp) and its interaction. The trials were conducted under greenhouse conditions at randomized design using four treatments replicated eight times for the evaluations made at 35 days, and four treatments for the evaluation at 60 days after inoculation. The first evaluation was determined the number of galls (NG) for M. javanica root system, and severity (SEV) for F. oxysporum f. sp. phaseoli. In assessing the 60 days, the analysis were identical to the first however, it was determined the factor of nematode reproduction (FR). For both evaluations, it was observed that M. javanica alone or in association with F. oxysporum, were parasite of all tested bean cultivars and lines. For F. oxysporum alone the cultivars 'Perola', 'IAPAR 14' and the line LP99-85, behaved as resistants. For the cultivar 'Perola', it was observed a significant increase of severity of the symptom of Fusarium when the fungi associated with M. javanica.

Effect of Iron Availability on Induction of Systemic Resistance to Fusarium Wilt of Chickpea by Pseudomonas spp

Selected isolates of Pseudomonas fluorescens (Pf4-92 and PfRsC5) and P. aeruginosa (PaRsG18 and PaRsG27) were examined for growth promotion and induced systemic resistance against Fusarium wilt of chickpea. Significant increase in plant height was observed in Pseudomonas treated plants. However, plant growth was inhibited when isolates of Pseudomonas were used in combination with Fusarium oxysporum f. sp. ciceri (FocRs1). It was also observed that the Pseudomonas spp. was colonized in root of chickpea and significantly suppressed the disease in greenhouse condition. Rock wool bioassay technique was used to study the effect of iron availability on the induction of systemic resistance to Fusarium wilt of chickpea mediated by the Pseudomonas spp. All the isolates of Pseudomonas spp. showed greater disease control in the induced systemic resistance (ISR) bioassay when iron availability in the nutrient solution was low. High performance liquid chromatography (HPLC) analysis indicated that all the bacterial isolates produced more salicylic acid (SA) at low iron (10microM EDDHA) than high iron availability (10microFe3+ EDDHA). Except PaRsG27, all the three isolates produced more pseudobactin at low iron than high iron availability.