Assessment of temporal and spatial genetic diversity of wheat streak mosaic virus using mobile nurseries and physical mapping of genes controlling agronomic traits present on chromosome 3A of wheat (Triticum aestivum)

Abstract

Grain yield loss due to wheat streak mosaic virus is very common in wheat especially in the Great Plains of the U.S.A. Variation among WSMV isolates is important for deployment of resistance wheat varieties. Using reverse transcriptase polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) analyses genetic variation was detected among and within WSMV populations collected from mobile nurseries for two years, four sampling dates and three geographical regions in Nebraska. According to analysis of molecular variance (AMOVA) results, genetic total variation within populations of each group accounted for approximately 90% of the variation. Less variation was detected among groups and populations within groups. Physical localization of the genes of interest in a specific wheat chromosome also provides valuable information in terms of increasing the grain yield. The second experiment used 41 Chinese spring lines with terminal deletions on chromosome 3 and 13 RFLP markers, which are found to be linked to the trait loci (QTLs) in wheat. The results suggested that two chromosomal regions on group 3A chromosome contained those QTLs and appear to be highly recombinogenetic, hence, are amenable to further molecular characterizations. The objectives of this study are: (1) To address the levels of genetic diversity and genetic structure in coat protein sequence of WSMV isolates, (2) To compare distribution patterns of WSMV isolates with respect to differentiation by mite transmission and host/environmental conditions, (3) To physically localize genes linked to the agronomic traits or QTLs. This study will help breeders use suitable isolates to screen wheat for WSMV resistance and pathologists understand the range of factors in WSMV epidemiology. It will also be helpful in cloning genes including but not limited to yield genes and disease resistance genes