Root-knot nematodes belonging to the genus
are agriculturally important pests, and biocontrol strategies offer safer alternatives for their management. In the present study, two fungal species from ...Indian soils were identified as
and
based on morphological characteristics and further confirmed using molecular markers.
evaluation of
against
and
showed 82 and 73% parasitism, respectively, whereas
gave 65.2 and 57.7% parasitism, respectively. Similarly, culture filtrates of
caused 57.7 and 53.7% mortality of
and
, respectively, whereas
caused higher mortality of 87.3 and 64%, respectively. Besides, greenhouse evaluation of both fungi against
infecting tomato significantly reduced nematode disease burden reflecting parasitic success measured as the total number of galls, egg masses, eggs per egg mass, and derived nematode multiplication factor. Application of
and
reduced nematode multiplication factor by 80 and 95%, respectively, compared with control. General metabolite profiling of tested fungi using gas chromatography-mass spectrometry and ultra-performance liquid chromatography-quadrupole/time of flight mass spectrometry reported for the first time here showed presence of various volatile and non-volatile compounds with nematicidal activity,
, trimethyl-heptadiene, methyl-hexadecanol, dodecadienal, decane, terpendole E, dodecane, acetamido-6-anthraquinone, and hexadecanol. Also, other compounds such as undecane, dibutyl-disulfide, octadecenal, paganin, talathermophilin, dactylarin, tolypyridone A, tolypyridone B, pyridoxatin, and destruxin were identified, reported in the literature to possess antibacterial, antifungal, and insecticidal properties. This is the first report of the occurrence of both fungi from India and pioneer demonstration of
for root-knot nematode management.
Sustainable food production is necessary to meet the demand of the incessantly growing human population. Phytopathogens pose a major constraint in food production, and the use of conventional ...fungicides to manage them is under the purview of criticism due to their numerous setbacks. In the present study, essential oil-grafted copper nanoparticles (EGC) were generated, characterized, and evaluated against the maize fungal pathogens,
f. sp.
, and
. The ED
for the fungi under study ranged from 43 to 56 μg ml
, and a significant inhibition was observed at a low dose of 20 μg ml
under
conditions. Under net house conditions, seed treatment + foliar spray at 250 and 500 mg L
of EGC performed remarkably against maydis leaf blight (MLB), with reduced percent disease index (PDI) by 27.116 and 25.292%, respectively, in two
seasons (May-Sep, 2021, 2022). The activity of enzymatic antioxidants,
, β-1, 3-glucanase, PAL, POX, and PPO, and a non-enzymatic antioxidant (total phenolics) was increased in treated maize plants, indicating host defense was triggered. The optimum concentrations of EGC (250 mg L
and 500 mg L
) exhibited improved physiological characteristics such as photosynthetic activity, shoot biomass, plant height, germination percentage, vigor index, and root system traits. However, higher concentrations of 1,000 mg L
rendered phytotoxicity, reducing growth, biomass, and copper bioaccumulation to high toxic levels, mainly in the foliar-sprayed maize leaves. In addition, EGC and copper nanoparticles (CuNPs) at 1,000 mg L
reduced the absorption and concentration of manganese and zinc indicating a negative correlation between Cu and Mn/Zn. Our study proposes that the CuNPs combined with EO (Clove oil) exhibit astounding synergistic efficacy against maize fungal pathogens and optimized concentrations can be used as an alternative to commercial fungicides without any serious impact on environmental health.
A desirable substitute for chemical pesticides is mycopesticides. In the current investigation, rDNA-ITS (Internal transcribed spacer) and TEF (Transcriptional Elongation Factor) sequencing were used ...for molecular identification of six
Beauveria bassiana
strains. Both, leaf discs and potted plant bioassaye were carried out to study their pathogenicity against the cassava mite,
Tetranychus truncatus
. LC
50
and LC
90
values of potential
B
.
bassiana
strains were estimated. We also discovered a correlation between intraspecific
B
.
bassiana
strains pathogenicity and comprehensive metabolome profiles. Bb5, Bb6, Bb8, Bb12, Bb15, and Bb21 strains were identified as
B
.
bassiana
by sequencing of rDNA-ITS and TEF segments and sequence comparison to NCBI (National Center for Biotechnology Information) GenBank. Out of the six strains tested for pathogenicity, Bb6, Bb12, and Bb15 strains outperformed against
T
.
truncatus
with LC
50
values 1.4×10
6
, 1.7×10
6
, and 1.4×10
6
and with a LC
90
values 7.3×10
7
, 1.4×10
8
, and 4.2×10
8
conidia/ml, respectively, at 3 days after inoculation and were considered as potential strains for effective mite control. Later, Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the above six
B
.
bassiana
strains was done on secondary metabolites extracted with ethyl acetate revealed that the potential
B
.
bassiana
strains (Bb6, Bb12, and Bb15) have higher levels of acaricidal such as Bis(dimethylethyl)-phenol: Bb6 (5.79%), Bb12 (6.15%), and Bb15 (4.69%). Besides, insecticidal (
n
-Hexadecanoic acid), and insect innate immunity overcoming compound (Nonadecene) were also identified; therefore, the synergistic effect of these compounds might lead toa higher pathogenicity of
B
.
bassiana
against
T
.
truncatus
. Further, these compounds also exhibited two clusters, which separate the potential and non-potential strains in the dendrogram of Thin Layer Chromatography. These results clearly demonstrated the potentiality of the
B
.
bassiana
strains against
T
.
truncatus
due to the occurrence of their bioactive volatile metabolome.
Fusarium wilt caused by
f. sp.
(
) is the most devastating disease of lentil present worldwide. Identification of multi-race fusarium wilt resistance genes and their incorporation into existing ...cultivars will help to reduce yield losses. In the present study, 100 lentil germplasms belonging to seven lentil species were screened against seven prevalent races of
, and accessions IC201561 (
subsp.
, EC714243 (
. subsp.
, and EC718238 (
were identified as resistant. The typical R gene codes for the nucleotide-binding site and leucine-rich repeats (NBS-LRR) at the C terminal are linked to either the Toll/interleukin 1-like receptor (TIR) or coiled coil (CC) at the N terminal. In the present study, degenerate primers, designed from the NBS region amplifying the P-loop to the GLPLA motif, isolated forty-five resistance gene analogues (RGAs) from identified resistant accessions. The sequence alignment identified both classes of RGAs, TIR and non-TIR, based on the presence of aspartate (D) and tryptophan (W) at the end of the kinase motif, respectively. The phylogenetic analysis grouped the RGAs into six classes, from LRGA1 to LRGA6, which determined the diversity of the RGAs present in the host. Grouping of the RGAs identified from
, LnRGA 2, 9, 13 with I2 revealed the structural similarity with the fusarium resistance gene. The similarity index ranged from 27.85% to 86.98% among the RGAs and from 26.83% to 49.41% among the known R genes, I2, Gpa2, M, and L6. The active binding sites present along the conserved motifs grouped the RGAs into 13 groups. ADP/ATP, being the potential ligand, determines the ATP binding and ATP hydrolysis activity of the RGAs. The isolated RGAs can be used to develop markers linked to the functional R gene. Furthermore, expression analysis and full-length gene isolation pave the path to identifying the molecular mechanism involved in resistance.
Beauveria bassiana
is an entomopathogenic fungus that causes the white muscadine disease in insects. The majority of entomopathogenic fungi are soil and insect borne, 15 soil samples were collected ...from seven different locations during 2021, from January to December. Similarly, during 2022, March to December, 15 fungus-infected insect specimens were collected from five different locations hence soil and insect samples from various ecosystems were collected. As a result, 30
B. bassiana
isolates from 11 different geographical areas were identified using morphological characteristics and multilocus sequence data in this investigation. The taxonomical positions of the isolates were determined using morphological characteristics and phylogenetic inferences based on three loci (Internal Transcribed Sequence, Elongation Factor-1α, and
B. bassiana
chitinase 1). In phylogenetic analysis of
B. bassiana
, the Maximum Likelihood analytical method produced distinct tree topology when compared to Neighbor-joining and minimum evolution. Three isolates
viz.
, Bb3, Bb7 and Bb20 were found closely linked with reference isolate (KTU-24) and other showed the higher population diversity among them. The genetic distances of 30
B. bassiana
isolates revealed that 15 were not closely related (D varied from 0.003 to 0.036). The pathogenicity of
B. bassiana
isolates from various hosts along with one commercial formulation (Beveroz) was assessed against
Tetranychus truncatus
under
in vitro
conditions by a completely randomized design (CRD) experiment. The same experiment was repeated thrice to confirm the pathogenicity of
B. bassiana
against
T. truncatus
. Later, the collected
T. truncatus
mortality data was converted into corrected mortality by using the Abbott formula and the values were examined using analysis of variance (ANOVA) in SPSS 23.0 software. Duncan’s Multiple Comparison Test was also done to compare the percentage mortality rates among the 30
B. bassiana
isolates. The recorded results showed that the Bb6, Bb15 and Bb12 isolates caused significantly higher mortality of
T. truncatus
, i.e., 97.73, 96.73 and 94.50% respectively, than the other isolates. This study showed the relativeness among the
B. bassiana
isolates and establishes their bio-efficacy against
T. truncatus
, which further can be used for commercialization as bio-pesticide.
The genus
Diaporthe
Nitschke (
Phomopsis
Sacc. & Harter) infect various agricultural and horticultural important crops and cause diseases such as damping off, leaf spots, blights, canker, dieback, ...wilt, root and fruit rots.
P. vexans, P. helianthi
and
P. phaseolorum
are the important species within genus causing huge yield and economic loss. Being primarily seed borne it also hinders import and export of germplasm and seeds. Therefore, extensive characterization is required to diagnose and manage the disease. Seventeen isolates collected from ITCC, IARI and ICAR-NBPGR belonging to eight species were morphological and molecularly characterized and diversity was analyzed. Several morphological and cultural characters were studied and analyzed. Due to lack of sufficient morphological variation to identify/differentiate species, molecular characterization using house-keeping genes, internal transcriber spacer (ITS) was carried out. ITS produced amplicon of ~ 600 bp in the isolates of
Phomopsis
and phylogenetic tree obtained revealed that isolates of a species belonging same geographic region had more sequence similarity than isolates belonging to different geographic regions this might be due to population adaption under varied environments. Development of EF-1alpha-based marker specific to
P. phaseolorum
helps in easily detection of pathogen in quarantine stations. In addition, species of
Phomopsis
were previously named based on host association which has led to misidentification and proliferation of species. Cross pathogenicity of isolates on three important hosts, brinjal, soybean and chilli revealed its broad host range and naming only basis of host association is unjustified.
In developing a
Trichoderma viride-
based biocontrol program for
Fusarium
wilt disease in chickpea, the choice of the quality formulation is imperative. In the present study, two types of ...formulations
i.e.
powder for seed treatment (TvP) and tablet for direct application (TvT), employing
T. viride
as the biocontrol agent, were evaluated for their ability to control chickpea wilt under field conditions at three dosages
i.e.
recommended (RD), double of recommended (DD) and half of recommended (1/2 RD). A screening study for the antagonistic fungi strains based on volatile and non-volatile bioassays revealed that
T. viride
ITCC 7764 has the most potential among the five strains tested (ITCC 6889, ITCC 7204, ITCC 7764, ITCC 7847, ITCC 8276), which was then used to develop the TvP and TvT formulations. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of volatile organic compounds (VOCs) of
T. viride
strain confirmed the highest abundance of compositions comprising octan-3-one (13.92%), 3-octanol (10.57%), and 1-octen-3-ol (9.40%) in the most potential
T. viride
7764. Further Physico-chemical characterization by standard Collaborative International Pesticides Analytical Council (CIPAC) methods revealed the optimized TvP formulation to be free flowing at pH 6.50, with a density of 0.732 g cm
-3
. The TvT formulation showed a pH value of 7.16 and density of 0.0017 g cm
-3
for a complete disintegration time of 22.5 min. The biocontrol potential of TvP formulation was found to be superior to that of TvT formulation in terms of both seed germination and wilt incidence in chickpea under field conditions. However, both the developed formulations (TvP and TvT) expressed greater bioefficacy compared to the synthetic fungicide (Carbendazim 50% WP) and the conventional talc-based formulation. Further research should be carried out on the compatibility of the developed products with other agrochemicals of synthetic or natural origin to develop an integrated disease management (IDM) schedule in chickpea.
This study evaluates the biocontrol efficacy of three bacterial strains (Pseudomonas fluorescens DTPF-3, Bacillus amyloliquefaciens DTBA-11, and Bacillus subtilis DTBS-5) and two fungal strains ( ...Trichoderma harzianum Pusa-5SD and Aspergillus niger An-27) antagonists, along with their combinations at varying doses (5.0, 7.5, and 10.0 g/kg of seeds), against wheat powdery mildew. The most effective dose (10 g/kg seeds) was further analyzed for its impact on induced resistance and plant growth promotion under greenhouse conditions. The study measured defense enzyme activities, biochemical changes, and post-infection plant growth metrics. All tested microbial antagonists at 10 g/kg significantly reduced PM severity, with B. subtilis strain DTBS-5 outperforming others in reducing PM severity and achieving the highest biocontrol efficacy. It was followed by B. amyloliquefaciens strain DTBA-11 and P. fluorescens strain DTPF-3, with the fungal antagonists showing no significant effect. Wheat crops treated with B. subtilis strain DTBS-5 exhibited substantial increases in defense-related enzyme activities and biochemicals, suggesting an induced resistance mechanism. The study found a 45% increase in peroxidase (POD) activity, a 50% increase in catalase (CAT) activity, a 30% increase in phenolic content, and a 25% increase in soluble protein content in the wheat plants treated with microbial antagonists. The study highlights the effectiveness of microbial antagonists, particularly B. subtilis strain DTBS-5, in managing wheat PM through biocontrol, induced resistance, and enhanced plant growth, offering a sustainable alternative to chemical treatments.
Stemphylium
leaf blight, caused by
Stemphylium vesicarium
, is a very important fungal disease in onions since its epidemics are able to affect both the bulb yield and the seed quality. The aim of ...this study was to screen onion genotypes at stage I (seed to bulb) and further screen the identified resistant and susceptible genotypes at stage II (bulb to seed). One hundred and fifty-seven genotypes were screened against SLB under artificially inoculated field conditions. Results revealed a significant variation among the morphological and biochemical traits studied. Correlation studies revealed a significant and negative correlation between percent disease incidence (PDI), pseudostem width, neck thickness, and dry matter. Fifteen genotypes were identified as moderately resistant, and the rest were categorized as susceptible. Bulbs of the genotypes, identified as moderately resistant, were again screened for resistance in stage II. All the genotypes were categorized as moderately susceptible. Biochemical analysis revealed that total foliar phenol content, pyruvic acid, catalase, and peroxidase increased up to 20 days after inoculation (DAI) and thereafter declined. Protein content was highest in the initial stage and declined at 10, 20, and 30 DAI. The higher biochemical activity was observed in moderately resistant category genotypes compared with the susceptible ones. Correlation analysis showed a highly significant and negative correlation of PDI with total foliar phenol content (TFPC), pyruvic acid, catalase, peroxidase, and protein content. To conclude, it was observed that screening against SLB should be done at both the stages (stage I and Stage II) to identify resistant onion genotypes. Direction selection for genotypes with high dry matter, higher phenols, and enzymes may be an alternative pathway to select genotypes for a robust resistance breeding program.
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