Abstract
Peanut (Arachis hypogaea L.) is the third most important oilseed crop in the world. The cultivated area in Mexico is currently 52,046 ha with a production of 91,109 ton in 2018 (FAO, 2020). Puebla state ranks third in the national production with 9,313 ton (SIAP, 2020). In September 2019, typical symptoms of charcoal rot (Macrophomina phaseolina (Tassi) Goid.) were observed in about 50% of cultivar Virginia Champs peanuts, and it affecting 1.5 ha located in Chietla (18° 27' 39" N; 98° 37' 11" W), Puebla, Mexico. Diseased plants showed brown discoloration in stem and root rot, with chlorotic foliage, dark microsclerotia were observed on the stem and premature dying. To isolate the causal agent of these symptoms, 20 infected plants were recovered and processed in the laboratory. Ten pieces of stem and root tissue were selected from each plant, cut into small pieces 5-mm in length, superficially disinfested with 1% sodium hypochlorite for 3 min, followed by three rinses with sterile distilled water. Later, dried on sterile paper and placed on Petri plates containing potato dextrose agar (PDA) medium, which were kept at 28°C for 7 days (12 h light and 12 h dark). Four colonies were purified via hyphal tip culture, fungus was consistently isolated from the analyzed tissues; additional microcultures were prepared to observe phenotypic characteristics. Colonies showed dense growth, with a gray initial mycelium, becoming black after 7 days. Microesclerotia with spherical to oblong in shape were observed after 5 days on PDA, with a black coloration, measuring an average of 74 µm width × 110 µm length (n=40). Phylogenetic analysis was conducted by amplification and sequencing of the internal transcribed spacer (ITS) region with the ITS5 and ITS4 primers (White et al. 1990). The obtained sequences were deposited in GenBank database under accession numbers: MW585378, MW585379, MW585380, and MW585381 containing approximately 601 bp of the ITS1-5.8S-ITS2 region (complete sequence); they were 99% identical with the reference sequence of Macrophomina phaseolina (GenBank accession KF951698) isolated in Phaseolus vulgaris from Mexico. Based on the symptoms in the field, colony morphology, color, and shape of the microsclerotia, and molecular identification, the fungus was identified as M. phaseolina (Tassi) Goid. The pathogenicity test was performed on peanut plants cultivar Virginia Champs grown on plastic pots with an autoclaved peat/soil mixture under greenhouse conditions (70% relative humidity and 28°C). Fifty two-month-old peanut plants were inoculated using the toothpick method. The toothpicks were previously sterilized and then placed in Petri plates with each of the four colonies of M. phaseolina until colonization. Small wounds were made with those toothpicks in the roots, and a sterile toothpick was used in the control plants, the assays were performed twice. After three weeks, the inoculated plants exhibited symptoms of wilting chlorosis on the leaves and brown to dark brown discoloration of the vascular ring, while control plants remained healthy. M. phaseolina was re-isolated from symptomatic root tissues and identified by phylogenetic approach, fulfilling Koch's postulates. To date, this fungus affects at least 372 hosts globally causing yield losses. Although in Mexico this fungus has been documented in Glycine max, Ipomoea batatas, Phaseolus vulgaris, Physalis ixocarpa, Saccharum officinarum, Sesamum indicum, Solanum melongena, S. tuberosum, and Sorghum bicolor (Farr and Rossman 2021). However, there are no reports of M. phaseolina as a potential pathogen on peanut; therefore, according to our knowledge, this is the first report of this fungus affecting A. hypogaea in Mexico.
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Claims 8
Claim · model-written summary
Typical charcoal rot symptoms were observed in about 50% of cultivar Virginia Champs peanuts in a 1.5 ha field in Puebla, Mexico.
- Taxon
- Peanut (Arachis hypogaea)
Arachis hypogaeat0 - Material
- Virginia Champse0
- Interactor
- Macrophomina phaseolina
Macrophomina phaseolinae0pathogen - Outcome
- symptoms of charcoal rote0
- Value
- about 50%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“typical symptoms of charcoal rot (Macrophomina phaseolina (Tassi) Goid.) were observed in about 50% of cultivar Virginia Champs peanuts”
Claim · model-written summary
Diseased peanut plants showed brown stem discoloration, root rot, chlorotic foliage, microsclerotia on the stem and premature dying.
- Taxon
- Peanut (Arachis hypogaea)Arachis hypogaeat0
- Outcome
- brown discoloration in stem and root rot, with chlorotic foliagee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“Diseased plants showed brown discoloration in stem and root rot, with chlorotic foliage, dark microsclerotia were observed on the stem and premature dying”
Claim · model-written summary
Microsclerotia on PDA averaged 74 um width by 110 um length.
- Taxon
- Peanut (Arachis hypogaea)Arachis hypogaeat0
- Outcome
- Microesclerotiae0
- Value
- 74 µm width × 110 µm lengthe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“Microesclerotia with spherical to oblong in shape were observed after 5 days on PDA, with a black coloration, measuring an average of 74 µm width × 110 µm length (n=40)”
Claim · model-written summary
ITS sequences of the isolates were 99% identical with the reference sequence of Macrophomina phaseolina.
- Taxon
- Peanut (Arachis hypogaea)Arachis hypogaeat0
- Interactor
- Macrophomina phaseolinaMacrophomina phaseolinae0pathogen
- Outcome
- identical with the reference sequencee0
- Value
- 99%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“they were 99% identical with the reference sequence of Macrophomina phaseolina (GenBank accession KF951698)”
Claim · model-written summary
The fungus was identified as M. phaseolina from symptoms, colony morphology, microsclerotia and molecular identification.
- Taxon
- Peanut (Arachis hypogaea)Arachis hypogaeat0
- Interactor
- M. phaseolinaMacrophomina phaseolinae0pathogen
- Outcome
- fungus was identified as M. phaseolinae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“the fungus was identified as M. phaseolina”
Claim · model-written summary
Peanut plants inoculated with M. phaseolina showed wilting chlorosis and vascular discoloration after three weeks, while control plants remained healthy.
- Taxon
- Peanut (Arachis hypogaea)Arachis hypogaeat0
- Treatment
- inoculatede0
- Interactor
- M. phaseolinaMacrophomina phaseolinae1pathogen
- Outcome
- symptoms of wilting chlorosis on the leaves and brown to dark brown discoloration of the vascular ringe0
- Comparator
- control plantse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“After three weeks, the inoculated plants exhibited symptoms of wilting chlorosis on the leaves and brown to dark brown discoloration of the vascular ring, while control plants remained healthy”
e1“colonies of M. phaseolina”
Claim · model-written summary
M. phaseolina was re-isolated from symptomatic roots and identified by phylogenetic approach, fulfilling Koch postulates.
- Taxon
- Peanut (Arachis hypogaea)Arachis hypogaeat0
- Interactor
- M. phaseolinaMacrophomina phaseolinae0pathogen
- Outcome
- re-isolated from symptomatic root tissuese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“M. phaseolina was re-isolated from symptomatic root tissues and identified by phylogenetic approach, fulfilling Koch's postulates”
Claim · model-written summary
This is the first report of M. phaseolina affecting A. hypogaea in Mexico.
- Taxon
- Peanut (Arachis hypogaea)Arachis hypogaeat0
- Outcome
- first report of this fungus affecting A. hypogaeae0
- Setting
- Mexicoe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Peanut (Arachis hypogaea)”
e0“this is the first report of this fungus affecting A. hypogaea in Mexico”
The same questions in other papers
inoculation · Macrophomina phaseolina · Arachis hypogaea (peanut)Positive and negative results
2 papers in the same direction as this paper · 2 in the opposite direction
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- positive
- negative
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