|Scofield, Steven - Steve|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/20/2007
Publication Date: 12/1/2007
Citation: Reddy, L., Friesen, T.L., Meinhardt, S.W., Chao, S., Scofield, S.R., Faris, J.D. 2007. Wheat-rice colinearity and chromosome walking at the Snn1 locus in wheat. Meeting Abstract. National Wheat Genomics Conference Abstracts. pg 28
Technical Abstract: The wheat fungal pathogen Stagonospora nodorum causes Stagonospora nodorum blotch (SNB) and produces multiple host-selective toxins that interact with specific host genes to cause disease. Snn1 is a dominant gene that confers sensitivity to the host selective toxin SnTox1. Previous genetic and cytogenetic analysis showed that Snn1 maps to a gene rich region on the short arm of chromosome 1B and was located distal to the 1BS-18 deletion breakpoint. We developed a saturated map of the Snn1 region using RFLPs, SSRs, and bin-mapped ESTs, which contained 51 markers spanning a genetic distance of 64.6 cM. Markers closely linked to Snn1 were used to develop a high-resolution map of the locus in a population of 4,255 F2 plants. Snn1 was delineated to a 0.46 cM interval and two ESTs were found to co-segregate with Snn1. Of the 44 ESTs mapped within the Snn1 region, 20 had homology with rice sequences on 9 different chromosomes. Eight of these ESTs had homology to genes on rice chromosome 5 but were not colinear due to numerous complex chromosomal rearrangements in wheat compared to rice. We initiated chromosome walking at the Snn1 locus using the Langdon durum BAC library and assembled a 595 kb contig. BAC sequencing and annotation revealed 10 possible candidates for Snn1. Genetic analysis using contig-derived markers indicated variable recombination frequencies within the Snn1 region. Functional validation of the candidate genes using virus-induced gene silencing (VIGS) is in progress.