טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentWachsman Guy
SubjectToward Cloning of the Tomato WIRY Genes
DepartmentDepartment of Biology
Supervisor Professor Emeritus Eliezer Lifschytz


Abstract

Mutations in each of three WIRY genes in the cultivated tomato, Lycopersicon esculentum, exhibit a unique pleiotropic syndrome, affecting all above ground organs. The most prominent phenotype of wiry mutant plants is the complete reduction of the compound leaves to wire like organs (hence the name of the gene) as well as the loss of apical dominance and sympodial architecture which together result in plants with a bushy appearance. In order to understand the molecular mechanisms controlled by the WIRY genes in wild-type plants, it is essential to clone first one of this genes using map-based protocols. By exploiting the highly dense molecular map of tomato I have screened and identified recombinants, flanking the WIRY4 gene from among 1350 plants in an F2 segregating population and used them to delimit the gene between two close markers and to build a contig in the genomic region containing the gene. Based on the phenotypic resemblance between the wiry mutations and argonaute1 mutants of Arabidopsis I have also mapped seven tomato ESTs of the ARGONAUTE family to eight different loci, one of which is linked with the WIRY1 gene. Plants bearing the wiry mutations are similar to the CMV (Cucumber Mosaic Virus) syndrome which was shown to suppress PTGS, in which ARGONAUE1 is also involved. Therefore, the wiry phenotype can be the results of suppression of the PTGS mechanism by the CMV or caused by mutations in tomato ARGONAUTE genes which encode one or more of the WIRY genes.