", sp. nov., is an emerging root-associated pathogen responsible for ta" by Teddy Garcia-Aroca, Paul P. Price et al.

Faculty Publications

Title

, sp. nov., is an emerging root-associated pathogen responsible for taproot decline of soybean in the southern United States

Authors

Teddy Garcia-Aroca, Department of Plant Pathology and Crop Physiology, Louisiana State University, Baton Rouge, Louisiana 70803.
Paul P. Price, LSU AgCenter, Macon Ridge Research Station, Winnsboro, Louisiana 71295.
Maria Tomaso-Peterson, Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Starkville, Mississippi 39762.
Tom W. Allen, Delta Research and Extension Center, Mississippi State University, Stoneville, Mississippi 38776.
Tessie H. Wilkerson, Delta Research and Extension Center, Mississippi State University, Stoneville, Mississippi 38776.
Terry N. Spurlock, Department of Entomology and Plant Pathology, University of Arkansas System Division of Agriculture Cooperative Extension Service, Lonoke, Arkansas 72086.
Travis R. Faske, Department of Entomology and Plant Pathology, University of Arkansas System Division of Agriculture Cooperative Extension Service, Lonoke, Arkansas 72086.
Burt Bluhm, Department of Entomology and Plant Pathology, University of Arkansas, Fayetteville, Arkansas 72701.

Document Type

Article

Publication Date

1-1-2021

Abstract

Taproot decline (TRD) is a disease of soybean that has been reported recently from the southern United States (U.S.). Symptoms of TRD include foliar interveinal chlorosis followed by necrosis. Darkened, charcoal-colored areas of thin stromatic tissue are evident on the taproot and lateral roots along with areas of necrosis within the root and white mycelia within the pith. Upright stromata typical of can be observed on crop debris and emerging from infested roots in fields where taproot decline is present, but these have not been determined to contain fertile perithecia. Symptomatic plant material was collected across the known range of the disease in the southern U.S., and the causal agent was isolated from roots. Four loci, ⍺-actin (), β-tubulin (), the nuclear rDNA internal transcribed spacers (nrITS), and the RNA polymerase subunit II (), were sequenced from representative isolates. Both maximum likelihood and Bayesian phylogenetic analyses showed consistent clustering of representative TRD isolates in a highly supported clade within the species complex in the "HY" clade of the family Xylariaceae, distinct from any previously described taxa. In order to understand the origin of this pathogen, we sequenced herbarium specimens previously determined to be "" based on morphology and xylariaceous endophytes collected in the southern U.S. Some historical specimens from U.S. herbaria collected in the southern region as saprophytes as well as a single specimen from Martinique clustered within the "TRD" clade in phylogenetic analyses, suggesting a possible shift in lifestyle. The remaining specimens that clustered within the family Xylariaceae, but outside of the "TRD" clade, are reported. Both morphological evidence and molecular evidence indicate that the TRD pathogen is a novel species, which is described as .

Publication Source (Journal or Book title)

Mycologia

First Page

326

Last Page

347

Recommended Citation

Garcia-Aroca, T., Price, P. P., Tomaso-Peterson, M., Allen, T. W., Wilkerson, T. H., Spurlock, T. N., Faske, T. R., & Bluhm, B. (2021). , sp. nov., is an emerging root-associated pathogen responsible for taproot decline of soybean in the southern United States. Mycologia, 113 (2), 326-347. https://doi.org/10.1080/00275514.2020.1846965

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