Location: Cereal Crops ResearchTitle: Genomic analysis and delineation of the tan spot susceptibility locus Tsc1 in wheat
|RUNNING, KATHERINE - North Dakota State University|
|KARIYAWASAM, GAYAN - North Dakota State University|
|ZURN, JASON - Kansas State University|
|ACEVEDO, MARICELIS - Cornell University - New York|
|CARTER, ARRON - Washington State University|
|LIU, ZHAOHUI - North Dakota State University|
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2022
Publication Date: N/A
Interpretive Summary: Tan spot is a destructive disease of wheat caused by a fungal pathogen. The disease causes the death of leaf tissue reducing the wheat plant's ability to perform photosynthesis, and ultimately leading to a reduction of grain yield. The fungus feeds on dead tissue and thus produces proteins that target and interact with specific wheat genes to cause cell death. One of the fungal proteins, known as Ptr ToxC, targets the wheat gene Tsc1. Wheat lines that lack the Tsc1 gene lack the target for Ptr ToxC and are therefore genetically resistant to tan spot. Here, researchers developed tools and conducted genetic experiments to lay the groundwork toward the identification of the DNA sequence of the Tsc1 gene. The location of Tsc1 was narrowed to a small segment of wheat chromosome 1A, where there were five genes that could be Tsc1. These genes contained features typical of plant disease resistance genes. By determining which of the five is Tsc1, researchers will be able to develop molecular tools to rapidly and efficiently develop new wheat varieties with improved resistance to tan spot.
Technical Abstract: The necrotrophic fungal pathogen Pyrenophora tritici-repentis (Ptr) causes the foliar disease tan spot in both bread wheat and durum wheat. Wheat lines carrying the tan spot susceptibility gene Tsc1 are sensitive to the Ptr-produced necrotrophic effector Ptr ToxC. A compatible interaction results in leaf chlorosis, reducing yield by decreasing the photosynthetic area of leaves. Developing genetically resistant cultivars will effectively reduce disease incidence. Toward that goal, the production of chlorosis in response to inoculation with Ptr ToxC-producing isolates was mapped in two low-resolution biparental populations derived from LMPG-6 × PI 626573 (LP) and Louise × Penawawa (LouPen). In total, 58 genetic markers were developed and mapped, delineating the Tsc1 candidate gene region to a 1.4 cM genetic interval spanning 184 kb on the short arm of chromosome 1A. A total of five candidate genes were identified in Chinese Spring reference genome, each with protein domains characteristic of resistance genes. Mapping of the chlorotic phenotype, development of genetic markers, both for genetic mapping and marker-assisted selection, and the identification of Tsc1 candidate genes provide a foundation for map-based cloning of Tsc1.