Abstract #55

The ability to grow on extreme pH as a model trait for the Genetic Dissection of Quantitative Trait Loci (QTLs). Gal H. Romano, Martin Kupiec. Molec.microbiology and Biotec, Tel Aviv University, Tel Aviv, Israel.
   Most of the phenotypes in nature are controlled by multiple loci. Each locus only marginally contributes to the overall phenotype, which results from the different combinations and interactions of the various alleles. This network gives rise to a low correlation between genotype and phenotype and to a continuous quantitative phenotype with a normal distribution within a population. This low correlation has hampered the ability to identify QTLs. Although most of the interesting traits are multigenic (e.g., sensitivity to diseases), there is currently little knowledge about their genetic basis. The budding yeast is an excellent model system for the dissection of complex traits due to its genetic amenability. We use the ability of yeast to grow on extreme pH as a model trait for QTL mapping. Using newly developed statistical methods, we have estimated the heritability and the number of QTLs controlling this trait. Our methodology for QTL mapping involves incorporation of the complex QTL network into a known background followed by hybridization to DNA microarrays. Our results revealed 17 candidate regions containing QTLs that affect the ability to grow on high pH. We intend to map those QTLs, estimate their effect and their genotype-phenotype correlation. We will then analyze the relationship between various components of the genetic networks uncovered. Our results will shed light on the architecture and dynamics of complex genetic traits, and the methodology developed can be extended to other organisms.

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