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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED RESISTANCE TO SOYBEAN PATHOGENS AND PESTS

Location: Soybean/maize Germplasm, Pathology, and Genetics Research

Title: First report of Colletotrichum chlorophyti causing soybean anthracnose

Authors
item Yang, Hui-Ching -
item Haudenshield, James
item Hartman, Glen

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 15, 2012
Publication Date: October 1, 2012
Citation: Yang, H., Haudenshield, J.S., Hartman, G.L. 2012. First report of Colletotrichum chlorophyti causing soybean anthracnose. Plant Disease. 96:1699.

Interpretive Summary: Anthracnose of soybean is a fungal disease that occurs throughout the major soybean production areas of the world. The fungal species that cause soybean anthracnose infect all parts of the soybean plant. Anthracnose of soybean is caused by several Colletotrichum species. Petiole samples were collected from Alabama, Illinois, and Mississippi. Diseased tissues suspected of being caused by Colletotrichum species were cut into 1-2 cm in lengths, surface-disinfested, and placed on water agar to recover the fungus. Some of the isolates were identified as C. chlorophyti based on morphological characteristics. These isolates were inoculated on soybean plants, which developed necrosis of apical tissues and at the edge of young leaves and petioles. This is the first report of C. chlorophyti in the United States, and of it infecting soybean. This information will be useful to plant pathologists especially those in APHIS.

Technical Abstract: Anthracnose of soybean is caused by several Colletotrichum species. Petiole samples were collected from Alabama, Illinois, and Mississippi. Diseased tissues suspected of being caused by Colletotrichum species were cut into 1-2 cm in lengths, surface-disinfested, and placed on water agar. Pure cultures obtained by picking single spores from sporulating acevuli on tissue or hyphal tips on agar were transferred to acidic potato-dextrose agar (APDA) at 24 ± 1°C under 12 h cool-white fluorescent lighting. Isolates were grouped by their morphological characteristics. One group consisting of six isolates (4 from IL and 1 each from AL and MS) was identified as C. chlorophyti. Soybean plants (cv.Williams 82) at the V2-V3 stage were atomized with a suspension of fragmented mycelia (40 mg/mL) using one isolate from IL. Plants were kept in a moisture chamber with > 90% relative humidity for 48 h in the dark, and then transferred to normal growing conditions. Three days post-inoculation, necrosis of apical tissues and at the edge of young leaves and petioles were observed. Further comparisons based on sequence analyses of the partial ITS rDNA region, actin, ß-tubulin, GAPDH, and histone 3 genes resulted in = 96% identity of all the 5 sequences to two C. chlorophyti isolates. This is the first report of C. chlorophyti in the United States, and of it infecting soybean.

Last Modified: 11/26/2014