Triticale as a Source of Resistance to Wheat Streak Mosaic Virus and Triticum Mosaic Virus

Authors

Marcos Winicius Goncalves de Souza, University of Nebraska-LincolnFollow

First Advisor

Katherine Frels

Committee Members

Blaine Johnson, Satyanarayana Tatineni

Date of this Version

7-2024

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Agronomy

Under the supervision of Professor Katherine Frels

Lincoln, Nebraska, July 2024

Comments

Copyright 2024, Marcos Winicius Goncalves de Souza. Used by permission

Abstract

Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) present a great threat to wheat production in the Great Plains area of the United States due to the loss of photosynthetic area causing reductions in crop yields. Effective control of these viruses is limited to a few available strategies including controlling volunteer wheat and using currently identified resistant genes to both the vector and viruses. While effective, these genes show temperature sensitivity and yield drag, and evidence that the vectors and viruses can overcome them has been found. Thus, new methods of genetic resistance are urgently needed. Field observations have indicated that triticale (x Triticosecale Wittmack) exhibits strong tolerance to both viruses, suggesting it is a potential source of resistance genes to be introgressed in wheat. Our project aimed to characterize resistance to both viruses in a controlled environment with manual inoculation of WSMV and TriMV and under field conditions with natural inoculation. We tested 92 triticale genotypes from the University of Nebraska-Lincoln’s Small Grains breeding program and analyzed their phenotypic response to WSMV and TriMV. Under an initial screening in the greenhouse, eight genotypes were selected based on their response to the viruses and a validation study was conducted on them where they were inoculated with WSMV, TriMV, or co-infected with both. Our results show that four genotypes (NT23244, NT23245, NT23246, and NT21436) were not affected by WSMV and exhibited low symptoms of TriMV. These four tolerant genotypes also exhibited the lowest disease severity when co-infected with both viruses. Additionally, under field conditions, the four genotypes also exhibited lower symptoms, confirming their tolerance under different conditions. These findings highlight the potential of triticale as an alternative source for WSMV and TriMV resistance genes, thus helping manage these viral diseases to preserve wheat yield.

Advisor: Katherine Frels