F1000ResearchF1000Research2046-1402F1000 Research LimitedLondon, UK10.12688/f1000research.136445.1Brief ReportArticlesStudies on variability in mode of infection by the isolates of leaf pathogens isolated from diseased leaves of
Musa paradisiaca from Uttar Dinajpur District
Banana is (
Musa sp) one of the most exoteric and materialistic fruit crop of many tropical and subtropical areas in India. Banana leaf diseases, caused by several fungal pathogens are one of the major diseases. Among the fungi causing banana leaf diseases,
Curvulariasp/
C. lunata is one of the main causal organisms causing leaf spot disease in banana plant. Two fungal isolates- MUSLF-2, MUSLF-3 and one fungal isolate- MUSLF-1 were isolated from the infected leaf from Ramganj and Gotgaon locations. Based on light microscopic and scanning electron microscopic studies, MUSLF-2 and MUSLF-3 were identified as
Curvularia sp. After Koch’s postulate, three fungal isolates- MUSLF-2, MUSLF-3 [
Curvularia sp] and MUSLF-1 were applied in banana field along with foliar spray of spore suspensions. The symptoms were similar to those observed in the
in vitro detached leaf inoculation technique.
The present research work depicts about the severity of leaf spot diseases of
Musa paradisiaca and the nature of mode of infections exhibited by the fungal pathogens.
Curvularia sp.Leaf spot diseasesMusa paradisiacaKoch’s postulateScanning electron microscopyTransmission electron microscopyThe author(s) declared that no grants were involved in supporting this work.Introduction
Between December 2022 and January 2023, leaf spot disease was observed on leaves of field-grown banana plants in the Uttar Dinajpur District, West Bengal. Diseased leaf samples were collected from Ramganj (Lat - 25.64855° long - 88.430628°), Gotgaon (Lat - 25.646622° long - 20 88.440895°) and Kaluhar ((Lat - 25.637923° long - 88.444335°) places. Symptoms first appeared as yellowish-brown spots in the middle and margin of leaves. Symptoms range from a few lesions scattered across leaves to lesions densely covering large sections of leave (
Figure 1).
Collection of diseased leaf samples of banana.
Two fungal isolates - MUSLF-2, MUSLF-3 and one fungal isolate - MUSLF-1 were isolated from the infected leaf from Ramganj and Gotgaon locations onto potato dextrose agar amended with Monocef. Based on light microscopic and scanning electron microscopic studies, MUSLF-2 and MUSLF-3 were identified as
Curvularia sp. (
Figures 2 &
3). Koch’s postulate was successfully established for
Curvularia sp. causing leaf spot disease in banana. Disease symptoms were developed within seven days on inoculated detached leaves and in inoculated leaf surfaces, conidial germination was observed.
Curvularia sp. was reisolated from the infected spots. Leaf diseases by
Curvularia sp. or
Curvularia lunata or other species of
Curvularia were reported by previous researchers (
Addrah
et al., 2021;
Manzar
et al., 2021) in support of our research findings.
Transfer of diseased leaf samples to media and isolation of leaf pathogens from diseased banana leaves along with variability in their morphologies.
SEM view of MUSLF-2 and MUSLF-3 isolates; Test of pathogenicity and establishing Koch’s Postulates by MUSLF-2 and MUSLF-3 isolates -
<italic toggle="yes">Curvularia</italic> sp. (Spore suspension showing spore count).
Mycelial invasion of the pathogen in infected leaf was confirmed through the section of leaves under light microscope with cotton blue staining (
Figures 4 &
5). The surface morphology of healthy and
Curvularia sp. inoculated leaves were studied by scanning electron microscopy (
Figures 6 &
7). Changes in internal structures of healthy and
Curvularia sp. inoculated leaves were observed through transmission electron microscopy (
Figure 8). Role of
Curvularia in causing leaf spots in other crop plants was studied by researchers (
Khoo
et al., 2022;
Bandara
et al., 2022).
Leaf samples after artificial inoculation with spore suspension of MUSLF-2 and MUSLF-3 isolates -
<italic toggle="yes">Curvularia</italic> sp. - 1×10
<sup>3</sup> conidia/ml following detached leaf technique; Section of
<italic toggle="yes">Curvularia</italic> sp. infected leaf of
<italic toggle="yes">Musa paradisiaca</italic> under light microscope with cotton blue stain.
Section of MUSLF-1 infected leaf of
<italic toggle="yes">Musa paradisiaca</italic> under light microscope with cotton blue stain; Conidial germination observation under light microscope in
<italic toggle="yes">Curvularia</italic> sp. infected leaf of
<italic toggle="yes">Musa paradisiaca</italic> after artificial inoculation in detached leaf technique.
Conidial germination observation under Scanning Electron Microscopy (SEM) in
<italic toggle="yes">Curvularia</italic> sp. infected leaf of
<italic toggle="yes">Musa paradisiaca</italic> after artificial inoculation in detached leaf technique.
Hyphal observation under Scanning Electron Microscopy (SEM) in MUS LF-1infected leaf of
<italic toggle="yes">Musa paradisiaca</italic> after artificial inoculation in detached leaf technique.
Observation of internal structure of healthy and infected leaf of banana under Transmission Electron Microscope (TEM).
After Koch’s postulate, three fungal isolates- MUSLF-2, MUSLF-3 [
Curvularia sp.] and MUSLF-1 grown in sand maize meal media were applied in banana field along with foliar spray of spore suspensions (1×10
3 conidia/ml). Although the method of inoculation was somewhat artificial, the symptoms were similar to those observed in the
in vitro detached leaf inoculation condition (
Figures 9 &
10). Similar finding on first report of
Curvularia lunata causing leaf spots in banana plant from Uttar Dinajpur District is in support of our present research (
Chowhan and Chakraborty, 2022).
Preparation of sand maize meal media; Growth of
<italic toggle="yes">Curvularia</italic> sp. (MUSLF-2, 3) and MUSLF-1 isolate in sand maize meal media.
Application of
<italic toggle="yes">Curvularia</italic> sp. (MUSLF-2, 3) and MUSLF-1 grown sand maize meal media in rhizpspheric zone of banana and foliar spray of spore suspensions in leaves of
<italic toggle="yes">Musa paradisiacal</italic>; Establishment of leaf spot in field and confirmation of
<italic toggle="yes">Curvularia</italic> sp.
In a nutshell, the research finding focuses on the nature of symptoms of leaf spot diseases of banana and role of
Curvularia sp. in establishment of leaf spot through Koch’s postulate in detached leaf technique as well as in field condition.
Data availability
No data is associated with the research.
Acknowledgements
Authors take this opportunity to express earnest gratefulness to the Director of USIC - Scanning Electron Microscopy Unit, University of North Bengal for taking the scanning electron microscopic photographs and the Director of USIC-AIIMS, New Delhi for taking the transmission electron microscopic photographs.
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The first report of
Curvularia senegalensis causing leaf and floral spots on
Zinnia elegans in Sri Lanka.Ceylon J. Sci.2022;51:73–77.
10.4038/cjs.v51i1.7981ChowhanPChakrabortyAP:
First report of
Curvularia lunata (ON246070) causing leaf spot disease of banana from Raiganj, West Bengal, India.Plant Health Progress.2022;24:32–36.
10.1094/PHP-05-22-0054-RSKhooYWRosinaBAmiruddinS:
First report of
Curvularia lunata causing leaf spot on
Oryza sativa in Sabah, Malaysian Borneo.Plant Dis.2022.
3654188310.1094/PDIS-08-22-1939-PDNManzarNKashyapASSharmaP:
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10.1094/PDIS-03-21-0637-PDN10.5256/f1000research.149588.r275397Reviewer response for version 1KhooYing Wei12Referee
Chinese Academy of Agricultural Sciences, Beijing, China
Universiti Malaysia Sabah, Kota Kinabalu, Malaysia
Competing interests: No competing interests were disclosed.
3. Which one do you want to refer to,
Curvularia sp or
C. lunata?
4. Please restructure this sentence: “Two fungal isolates- MUSLF-2, MUSLF-3 and one fungal isolate- MUSLF-1 were isolated from the infected leaf from Ramganj and Gotgaon locations.”
5. Without molecular results, how can you confirm the isolates are either
Curvularia sp. or
Curcularia lunata based on macroscopic and microscopic characterization?
6. Remove “about” before “the severity”
7. Add “the” before “mode”
8. A scale bar should be added to the figure
In cases where a figure has multiple parts or panels, it is better to label each with a letter: A, B, C, etc. in lowercase or upper-head letters depending on the journal’s guidelines.
9. Figures no.5, 7, and 8 Figure 2 are not clear, same goes for some figures in Figures 3, 4, 9, and 10.
10. Your identification of the fungi lacks strong evidence to support its accuracy.
Is the work clearly and accurately presented and does it cite the current literature?
Partly
If applicable, is the statistical analysis and its interpretation appropriate?
Not applicable
Are all the source data underlying the results available to ensure full reproducibility?
Partly
Is the study design appropriate and is the work technically sound?
No
Are the conclusions drawn adequately supported by the results?
No
Are sufficient details of methods and analysis provided to allow replication by others?
No
Reviewer Expertise:
Plant Pathology
I confirm that I have read this submission and believe that I have an appropriate level of expertise to state that I do not consider it to be of an acceptable scientific standard, for reasons outlined above.