Poster: Organelle Biogenesis

Abs # 1165: Mapping and characterization of the vir2 mutant in Arabidopsis thaliana

Presenter:	Thissen, Michelle M, swinggene@yahoo.com
Authors	Thissen, Michelle M (A)   Hedden, Lee  (A)   Vavilin, Dimitrii  (B)   Brusslan, Judy  (A)
Affiliations:	(A): California State University Long Beach (B): Arizona State University

We are attempting to determine the characteristics and the molecular identity of the virescent 2 (VIR2) gene in Arabidopsis thaliana. Wild type plants accumulate chlorophyll at normal levels, while vir2 mutants show a delay in greening with the youngest leaves displaying the most acute phenotype. We have made Col x Ler mapping population of 500 individuals. The population was screened with markers in hopes of finding genetic loci that would cosegregate with vir2. It was determined that the vir2 gene is located on chromosome one approximately 5.5 map units from the microsatellite marker nga280 and 10 map units from GAPB. Recent data has shown that a marker on BAC F13F21 is less than 0.4 map units away, while no recombinants were recovered using markers on BAC F2J10, and one recombination was found on BAC F14J22. We are also determining the phenotype of the vir2 mutant. Chlorophyll readings show a large reduction in the chlorophyll per milligram tissue in low or moderate light and a lower the chlorophyll a/b ratio that follows the same adjustments to moderate light as wild type. Non-denaturing green gels suggest no gross changes in pigment protein complexes and 77K fluorescence data suggest an increase in emissions between 700-710nm and a second smaller increase at 667nm. Ultrastructure of vir2 chloroplast will also be presented.