Rama S. Kota

Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)




Wheat streak mosaic is a serious virus disease that threatens the production of winter wheat in. some areas of the United States. It is caused by a virus transmitted by a wheat-curl mite, Aceria tulipae Keifer. Immunity from the virus has not been found in Triticum species but tolerance to some strains of the virus has been reported. An obvious way to improve this important crop plant is to exploit the variability of its relatives. A good source of immunity found in Agropyron intermedium Beau (2n = 70) has been used in crosses with common wheat, Triticum aestivum L. em, Thell. Transferring the immunity has been difficult because homoeologous chromosomes will not pair due to the presence of a gene on 5BL that acts as a suppressant. Interchanges between chromosomes can be achieved in several ways. One is by irradiation. Another is by removing or suppressing a dominant gene on 5B that prevents paring of homoeologous. A third is by taking advantage of the joining of two telocentrics from different chromosomes originating from misdivision. The transfer of characters to wheat from alien species contributes to our understanding of evolutionary relationship and may improve common wheat. If the interchanged segments are homoeologous and compensating, they are transmitted normally through egg and pollen. Once transfers are achieved, it is desirable to evaluate the derived lines cytologically and agronomically. The purposes of this study are two-fold. One is to characterize lines cytologically. Chromosome paring in F1 hybrids can indicate the size and nature of translocations. In the Triticinae, chromosome paring can be reduced as a result of chromosomal structural differentiation. The second purpose is to measure the effects of the Agropyron chromatin on the phenotypes of the lines studies in relation to the recurrent parent, Centurk, and to one another.

Library of Congress Subject Headings

Wheat -- Diseases and pets
Wheat streak mosaic virus
Translocation (Genetics)



Number of Pages



South Dakota State University