Fusarium Udum Research Articles

Assessment of diversity and plant growth promoting attributes of rhizobia isolated from Cajanus cajan L.

Eight (8) strains of rhizobia from Pigeon pea ( Cajanus cajan ) were isolated and identified based on their physiological and biochemical characteristics using standard methods. Five (5) of the isolates (KCC1 to KCC5) were subjected to partial 16S rDNA gene sequencing for phylogenetic analysis. Genetic diversity was investigated using restriction patterns produced by amplified rDNA restriction analysis (ARDRA) and were placed into different clusters. They were identified as Ensifer sinorhizobium hence named as Ensifer spp. KCC1 to KCC4. KCC5 is placed in Ensifer fredii clade. Nodulation and nitrogen fixing abilities of the isolates were confirmed by amplification of nod C and nif H genes. All of them showed indole-3-acetic acid production and phosphate solubilization activity. Only two isolates (KCC2 and KCC5) produced siderophore on CAS medium and showed strong antagonistic effect against Fusarium udum . None of the isolates produced cyanogen. The study showed that there is a considerable homogeneity amongst C. cajan root nodule isolates and can be exploited for plant growth promotion of C. cajan with effective antagonism against F. udum . Keywords: Diversity, Ensifer ( Sinorhizobium ) spp., pigeon pea ( Cajanus cajan )

Real-time PCR Assay Based on Topoisomerase-II Gene for Detection of Fusarium udum

Fusarium wilt is an important soilborne disease of pigeonpea, caused by Fusarium udum. In this study, we have designed a real-time PCR assay for the detection of Fusarium udum from infected pigeonpea plants. Based on Topoisomerase-II gene sequence data from Fusarium udum and other related Fusarium species, a pair of primer was designed. The species-specific primers were tested in real-time PCR SYBR green assay. No increasing fluorescence signals exceeding the baseline threshold was observed with tested microbes, except Fusarium udum DNA. A single dissociation peak of increased fluorescence was obtained for the specific primers at melting temperature of 81.25°C. The real-time PCR showed a lowest detection of 0.1pg genomic DNA. The assay was more sensitive, accurate and less time consuming for detection of Fusarium udum in infected plants root.

Jatrorrhizine and columbamine alkaloids isolated from Argemone mexicana are inhibitory to spore germination of some plant pathogenic fungi

The isomeric alkaloids jatrorrhizine and columbamine isolated from the whole plant of Argemone mexicana were assessed against spore germination of some fungi, e.g. Alternaria cajani, Bipolaris sp., Helminthosporium sp., Fusarium udum and Curvularia sp. Both the alkaloids were effective against most of the fungi tested. Jatrorrhizine was highly effective against spore germination of Bipolaris sp., Fusarium udum and Curvularia sp. at 5000 ppm concentration, whereas columbamine was highly effective against Alternaria cajani, Helminthosporium sp. and Fusarium udum at 5000 ppm.

Slow wilting components in pigeonpea (Cajanus cajan(L.) Millsp.)

Partial resistance to Fusarium wilt was characterized based on root inoculation on seven pigeonpea genotypes with a virulent isolate of Fusarium udum. Resistance to wilt seems to be mainly due to localization of the pathogen in roots and vascular systems in the stem. Three components of resistance (wilting rate or incubation period, weighted wilt index and number of colonized plants) were determined and compared to those of susceptible genotypes Bahar and TTB7. There were significant differences between the genotypes for the resistance components. The mechanisms of resistance in the genotypes appeared to be different, with genotype ICP8863, having a longer incubation period, minimum wilt index and minimum pathogen colonization as compared to other resistant genotypes (ICP9174, ICP87119 and ICP8858). Wilting rate or incubation period and number of colonized plant were significantly correlated with resistance in adult plants in the field (AUDPC). Wilt index was useful in discriminating between genotypes that had a similar incubation period and number of colonized plants. The partial character of resistance is probably based on quantitative differences in localization capacity among the genotypes. A quantitative relationship between components, incubation period and number of colonized plants and the AUDPC, if verified for a large number of genotypes, may be used to obtain an index of resistance that may predict resistance levels in the field.

Ethanolic extract of mango (Mangifera indica L.) malformed inflorescence as effective antifungal agent

Mango (Mangifera indica L.) suffers from floral and vegetative malformation and crop production is seriously affected. The anti-fungal activity of ethanolic extract of malformed mango inflorescence was observed at different concentrations (1000, 2000, 3000, 4000 and 5000 μl/ml) against 10 fungi, viz., Ustilago cynodontis, Cercospora cajani, Sphaerotheca sp., Cercospora sp., Alternaria solani, Bipolaris sp., Helminthosporium sp., Curvularia sp., Fusarium udum and Alternaria cajani. Spore germination of most of the fungi was inhibited at 5000 μg/ml. Some of them were also susceptible at 3000 or 4000 μg/ml concentration. Analysis of phenolic acids by high performance liquid chromatography (HPLC) showed 18 peaks in the extract, but only four could be identified, viz., capachin, gallic, benzoic and cinnamic acids. Because of the high efficacy of ethanolic extract of malformed mango inflorescence, its use under field conditions to control some plant diseases has been suggested.

The mixture of tertiary and quaternary alkaloids isolated from Argemone ochroleuca inhibits spore germination of some fungi

The mixture of tertiary and quaternary alkaloids isolated from Argemone ochroleuca was separately assessed against spore germination of some plant pathogenic fungi, e.g. Alternaria alternata, Alternaria brassicae, Alternaria cajani, Bipolaris sp., Curvularia lunata, Curvularia sp., Colletotrichum musae, Fusarium udum, Helminthosporium sp., Helminthosporium pennisetti and Helminthosporium speciferum. Spore germination of Fusarium udum and Helminthosporium sp. was completely inhibited at very low concentration (200 ppm). A similar effect was observed on A. alternata, C. musae and H. pennisetti at 600, 800 and 1000 ppm. With quaternary alkaloids, Curvularia sp. and Colletotrichum musae were most sensitive as complete inhibition of spore germination was observed at 400, 600, 800 and 1000 ppm and a similar effect was observed with A. brassicae and A. cajani at 600, 800 and 1000 ppm. The remaining fungi were also highly sensitive to the mixture at different concentrations.

Development of early maturing fusarium wilt resistant pigeonpea cultivars

Most of the East African pigeonpea ( Cajanus cajan (L.) Millsp) landraces are tall (up to 3.5 m), late maturing (10-12 months), low yielding and susceptible to Fusarium wilt ( Fusarium udum Butl.), one of the most serious fungal diseases in the region. Breeding populations were created by hybridization of the local landraces and early maturing, small and brown seeded Indian genotypes in 1984 and 1985. Selection for reduced height, early maturity, grain yield, seed colour and size, and resistance to Fusarium wilt was conducted for seven generations. Selected lines were evaluated at two Fusarium wilt infested plots for two years and also in a wilt infested soil in a glasshouse. Ten lines that were resistant or tolerant to Fusarium wilt, early maturing, short in height, high yielding and with large, white/beige seeds were finally selected. High positive significant correlations (r = 0.87** and 0.62**) between glasshouse and two field sick plot disease ratings were observed.

Antifungal activity of the mixture of quaternary alkaloids isolated from Argemone mexicana against some phytopathogenic fungi

The anti-fungal activity of a mixture of quaternary alkaloids of Argemone mexicana was observed at different concentrations (1000, 2000, 3000, 4000 and 5000 μl/ml) against 10 fungi, viz., Ustilago cynodontis, Cercospora cajani, Sphaerotheca sp., Cercospora sp., Alternaria solani, Bipolaris sp., Helminthosporium sp., Curvularia sp., Fusarium udum and Alternaria cajani. Spore germination was inhibited at 2000, 3000, 4000, 5000 μg/ml. Analysis of phenolics by high performance liquid chromatography (HPLC) recorded 11 peaks in the alkaloids but only three could be identified, viz., tannic, caffeic and ferulic acids. The significant efficacy of the alkaloid under in vitro conditions may open the possibility of its use by farmers under field conditions for controlling some crop diseases.

Wilt disease management and enhancement of growth and yield of Cajanus cajan (L) var. Manak by bacterial combinations amended with chemical fertilizer

Root nodulating Sinorhizobium fredii KCC5 and Pseudomonas fluorescens LPK2 were isolated from nodules of Cajanus cajan and disease suppressive soil of tomato rhizosphere, respectively. Both strains produced IAA, siderophore, solubilized insoluble phosphate, showed chitinase and β-1,3-glucanase activities, and strongly inhibited the growth of Fusarium udum. It also caused degradation and digestion of cell wall components, resulting in hyphal perforations, empty cell (halo) formation, shrinking and lysis of fungal mycelia along with significant degeneration of conidia. LPK2 produced volatile cyanogen (HCN). Combinations of S. fredii KCC5 and P. fluorescens LPK2 with half dose of chemical fertilizers showed a significant increase in seed germination (94%) while seed germination with co-inoculated strains (KCC5 + LPK2), KCC5 and LPK2 alone was 90, 84 and 82% respectively as compared to control 77%. After 120 days of sowing, per plant number of pods, nodules, shoot length, root length, shoot weight and root weight were greater for the combination with half dose of chemical fertilizers compared to the control. Combinations of S. fredii KCC5 and P. fluorescens LPK2 with half dose of chemical fertilizers resulted in an 82% increase in grain yield per hectare compared to the control. Both strains KCC5 and LPK2 led to proto-cooperation as evidenced by synergism, aggressive colonization of the roots, and enhanced growth, suggesting potential biocontrol efficacy against Fusarium wilt in C. cajan.

Antifungal activity of two alkaloids of Zephyranthes citrina and their field efficacy against powdery mildew (Erysiphe cichoracearum) of balsam

The anti-fungal activity of two alkaloids isolated from bulbs of Zephyranthes citrina was observed against 10 fungi, viz, Aternaria solani, A. triticina, Curvularia lunata, C. maculuns, Cercospora malvacearum, Erysiphe sp., Fusarium udum, Helminthosporium pisi, H. speciferum and Ustilago cynodontis. Different concentrations (200, 400, 600, 800, 1000 µg/ml of alkaloids (A and B) were used. Spore germination was inhibited at 600, 800, 1000 µg/ml. B alkaloid was used against Erysiphe cichoracearum causing powdery mildew in balsam (Impatiens balsamina) in the field as pre- and post-inoculation treatments at 1000, 1500, 2000 µg/ml doses. The extract was effective in both pre- and post-inoculation treatments. Foliar application of this alkaloid resulted in inducing synthesis of phenolic acid in the leaves of balsam. Maximum phenolics were detected in the leaves treated with 1500 µg/ml in both pre- and post-inoculation treatments. The increase in the production of phenolics in treated leaves of balsam can be correlated with the induction of resistance in treated plants against powdery mildew. The significant efficacy of the alkaloid under field conditions opens the possibility of its use by farmers for also controlling other diseases.

Mass multiplication and formulations of biocontrol agents for use against fusarium wilt of pigeonpea through seed treatment

Trichoderma harzianum and Pseudomonas fluorescens are the two major fungal biocontrol agents found in the soil and the rhizosphere of various crop systems. We used different agricultural waste bases such as wheat bran, rice bran, paddy straw and neem cake for mass-multiplying T. harzianum and P. fluorescens. Ten isolates each of T. harzianum and P. fluorescens were isolated from rhizosphere soil samples collected from various pigeonpea-growing fields. We evaluated the efficacy of these isolates, both in increasing seed quality variables of pigeonpea and in inhibiting the mycelial growth of Fusarium udum Butler. Trichoderma harzianum isolate 4 and Pseudomonas fluorescens isolate 3 were selected and mass-multiplied using different agricultural waste products as bases. Among the latter, boiled rice bran was found to increase the growth of both biocontrol agents. Talc and sodium alginate formulations of mass-multiplied biocontrol agents were prepared and evaluated for their affects against fusarium wilt under greenhouse conditions. Fresh cultures of both biocontrol agents were found to increase seedling emergence and reduce fusarium wilt disease incidence when compared to the control and the formulations.

English

Wheat root and crown rot (Triticum aestivum L.) is a disease problem in many wheat producing area as well as Moghan wheat growing area, Northwest of Iran. In this study, injured plants of wheat with blighting, stunting, and death of mature plants, also necrotic lesions on seminal crown roots, sub crown internodes and crown, as well as basal stem tissue symptoms were collected from different regions of Moghan wheat growing area. Fungi associated with wheat root and crown rot were isolated and identified based on general colony morphology, the morphology of mycelia, reproductive structure and taxonomic description. Also pathogenicity of 28 selected isolates from various identified species was determined on wheat (T. aestivum L. CV. Atila 4; a common grown cultivar of wheat in Moghan area) seedlings. The results indicated that the predominant pathogens implicated in causing common root and crown rot in this study was Bipolaris sorokiniana. In addition to B. sorokiniana, Fusarium culmorum, Fusarium Pseudograminearum and Gaeumannomyces/Phiallophora complex are the most widely distributed species on wheat growing belt in Moghan area. Fusarium solani, Fusarium crookwellence, Fusarium clamidosporum, Fusarium proliferatum, Fusarium poa, Fusarium udum and Fusarium babinda are wheat root associated species of Fusarium ascertained during our investigation. Pathogenicity test revealed that B. sorokiniana, F. culmorum, F. graminearum, F. crookwellence, F. udum and Gaeumannomyces/Phiallophora complex are active pathogens and others are saprophytes, which are also involved in the destruction of root tissues, without being the cause of injury.

Evaluation of Trichoderma species against Fusarium udum Butler Causing Wilt of Pigeonpea

One isolate each of Trichoderma viride, Trichoderma harzianum and Trichoderma virens were evaluated against twelve isolates of Fusarium udum collected from different districts of Bihar, Jharkhand and West Bengal by dual culture technique. All the bioagents inhibited the growth of F. udum in vitro . Dholi isolate of T. harzianum inhibited the growth of F. udum isolates Fu-5, Fu-12, Fu-14, Fu-21, Fu-24, Fu-27 and Fu-43 by 40.8, 74.5 , 49.4, 59.1, 60.5, 40.8 and 57.8 per cent, respectively and proved superior to other antagonists. T. viride was found to have potential in inhibiting the radial growth of F. udum isolates Fu-29, Fu-37, Fu-49 and Fu-57 while T. virens was more effective in inhibiting the growth of Fu-61. Combined application of T. harzianum and T. viride as seed treatment and soil application gave minimum disease incidence (26.4%) and maximum disease control (56%) followed by 54% disease control in T. harzainu m seed treatment and soil application. However, these two treatments were on par with each others. The results also revealed that soil application of bioagents was more effective than seed treatment.

Fungal Biosolubilization of Neyveli Lignite into Humic Acid

Reported in the present article are the results of investigations on the biosolubilization of a low-rank coal, viz. lignite (from Neyveli, Tamil Nadu, India) into humic acid. The solubilization of lignite was effected at ambient temperature and pressure with the aid of some potent fungal strains isolated from soil samples collected from Neyveli lignite mines. The isolated fungal microbes were characterized and studied under controlled conditions for optimum solubilization of lignite. Of the isolated fungal strains, Aspergillus fumigatus showed maximum (22.3%, w/w) solubilization, as contrasted with other isolated microbes, e.g., Fusarium udum, Fusarium solani, Aspergillus oryzae, and Aspergillus sydowii, which showed much less solubilization, being in the range of 4.5–16.8% (w/w). The process parameters were optimized in respect of media, initial pH, incubation period, and substrate concentration for maximum yield of the product. The solubilization becoming constant after a certain dose of lignite (10 g/100 ml) has been explained on the basis of non-availability of the surface area on the lignite particles owing to clogging/blockage of pores by the debris of dead cells and their metabolites. It could also be attributed to the broth becoming too dense, thereby inhibiting the growth and propagation of the microbial cells or possibly due to inhibition by the substrate at higher doses.

Optimization and production of salicylic acid by rhizobacterial strain <italic>Bacillus licheniformis </italic> MML2501

The Rhizobacterial isolate Bacillus licheniformis MML2501 effectively inhibited the mycelial growth of fungal pathogens viz., Macrophomina phaseolina, Fusarium udum, Fusarium oxysporum, Bipolaris oryzae, Pyricularia oryzae, Alternaria alternata and Curvularia lunata. Bacillus licheniformis MML2501 was tolerant to heavy metals such as zinc, cobalt and selenium. B. licheniformis MML2501 was tolerant to fungicides such as propiconazole and tridemorph and showed moderate tolerance to tricyclazole and it was showed resistant to antibiotics such as ampicillin, streptomycin, bacitracin, cephalotitin, erythromycin and oxytetracycline. Bacillus licheniformis MML2501 produced salicylic acid (SA), with a maximum yield of 18 μg/ml in optimized culture conditions such as pH 7.0, temperature 30°C, casaminoacids at a concentration of 0.4 % and at 200 rpm shaken condition. SA produced by Bacillus licheniformis MML2501 was further confirmed by TLC and HPLC analyses, in which the Rf value and retention time of 0.61 and 5.24 min, respectively were matching with that of authentic SA. Therefore the present study suggests that the rhizobacterial strain Bacillus licheniformis MML2501 has merits to be a beneficial bacteria for the crop protection through systemic resistance.

Fungal Spore Germination Inhibition by Alkaloids Dehydrocorydalmine and Oxyberberine

The alkaloids dehydrocorydalmine and oxyberberine isolated from Argemone mexicana were assessed against spore germi- nation of some fungi, e.g., Alternaria cajani, Bipolaris sp., Helminthosporium sp., Fusarium udum and Curvularia sp. While dehydroco- rydalmine inhibited 100% spore germination of the fungi Helminthosporium sp. and Curvularia sp. at 5 000 ppm, oxyberberine showed similar activity against spore germination of Bipolaris sp. and Curvularia sp. All the five fungi were significantly inhibited at 1 000 to 5 000 ppm concentrations.

Biocontrol of wilt disease complex of pigeonpea by fluorescent pseudomonads andBacillusspp. under pot and field conditions

Six potential isolates of Bacillus and Pseudomonas (out of 20 isolates screened under green house assay) were evaluated under pot and field conditions for the biocontrol of wilt disease complex of pigeonpea caused by Heterodera cajani, Meloidogyne spp. and Fusarium udum . Isolate Pa324 was found best for the biocontrol of wilt disease complex of pigeonpea followed by B18, Pf18, Pa70, Pa116 and B160 under pot condition. Isolate Pa324 caused greater reduction in multiplication of M. incognita and H. cajani and also reduced wilting caused by F. udum . Isolate Pa324 produced greater amount of siderophores followed by Pf18, Pa70 and Pa116. Isolate Pa324 showed greater hydrogen cyanide and indole acetic productions than other isolates. Moreover, seedling growth was higher when seeds were treated with Pf18 followed by Pa324, Pa116, B160 and B18. Isolate Pf18 caused a similar increase in seedling growth as was caused by Pa70. Under field condition too isolate Pa324 was best in reducing wilt disease complex follow...

Factors effecting chitinase activity of Rhizobium sp. from Sesbania sesban

AbstractTwenty six Rhizobium strains isolated from root nodules of Sesbania sesban were studied for chitinase activity on chitin agar plates. Among them, only 12 strains showed chitinase activity. The strain showing the highest chitinase activity was selected based on maximum clear zone/colony size ratio on chitin agar plates and chitinase activity in culture filtrate. The strain was identified as Rhizobium sp. which showed a high degree of similarity with Rhizobium radiobacter (= Agrobacterium radiobacter). The cultural and nutritional conditions were optimized for maximum chitinase activity. The Rhizobium sp. exhibited maximum chitinase activity after 36 h of incubation, at neutral pH. Among the different nutritional sources, arabinose and yeast extract were found to be good inducers for chitinase activity. Rhizobium sp. could degrade and utilize dead mycelia of Aspergillus flavus, Aspergillus niger, Curvularia lunata, Fusarium oxysporum and Fusarium udum.

Management of disease complex caused by root knot nematode and root wilt fungus on pigeonpea through soil organically enriched with Vesicular Arbuscular Mycorrhiza, karanj (Pongamia pinnata) oilseed cake and farmyard manure

This investigation was undertaken to compare the percentage response of colonization and development of VA-Mycorrhiza (Glomus fasciculatum) on a number of pulse crops viz. cowpea, chickpea, soybean, pigeonpea and lentil under glasshouse conditions. Among the above-mentioned crops, pigeonpea exhibited the best performance and was selected for further studies. In this host the development and colonization percentage of G. fasciculatum was investigated under two separate substrates i. e. soil amended with FYM and karanj oilseed cake keeping a control treatment of field soil. A third treatment amended with karanj oilseed cake and farm yard manure (FYM) was also kept which responded best in terms of colonization percentage. This treatment showing improved plant health as well as integration with G. fasciculatum was selected as an ideal treatment for the management of disease complex caused by root knot nematode, Meloidogyne incognita and root wilt fungus, Fusarium udum on pigeonpea. Thus the treatment constituting FYM, karanj oilseed cake and VA-Mycorrhiza reduced the disease incidence caused by both maladies to a great extent with the most promising improvement in plant growth parameters as compared to all others. The present investigation, in addition to proposing an ideal eco-friendly treatment for the management of this disease complex also proposed an excellent medium for the proliferation of the obligate bio-protectant, G. fasciculatum.

SCREENING OF BACILLUS ISOLATES FOR POTENTIAL BIOCONTROL OF THE WILT DISEASE COMPLEX OF PIGEON PEA (CAJANUS CAJAN) UNDER GREENHOUSE AND SMALL-SCALE FIELD CONDITIONS

Twenty isolates of unidentified Bacillus species were obtained from pathogen-suppressive soils of pigeon pea (Cajanus cajan) fields for the biocontrol of a wilt disease complex caused by Heterodera cajani; Meloidogyne incognita and Fusarium udum. Five isolates (B602; B603; B605; B615 and B618) were considered to have biocontrol potential on the basis of antifungal activity; inhibitory effect on the hatching and penetration of nematodes and colonization of pigeon pea roots by these isolates. The five Bacillus isolates were evaluated for biocontrol potential under pot conditions. Isolates B615 and B603 were found to be the most promising and should be further studied in field experiments.