Functional genomics study in Arabidopsis thaliana of histidine biosynthesis

Abstract

This study was aimed at analyzing the function of a gene thought to be required for histidine biosynthesis in the vascular plant Arabidopsis thaliana. A DNA insertion mutant of locus At2g36230 was isolated. Based on homology with the Saccharomyces cerevisiae His6 gene, At2g36230 was predicted to encode phosphoribosylformimino-5-aminoimidazole carboximide ribotide isomerase. Individual plants heterozygous for the AtHis6::TDNA insertion allele produced siliques in which approximately 25% of the seeds were aborted during early embryo development. The vegetative phenotype of the heterozygous plants was normal. When histidine was applied exogenously to the heterozygous plants the frequency of embryo-abortion was reduced to approximately 5%. The fact that the homozygous mutant seeds fail to grow while the maternal plant thrives suggests that histidine, unlike other amino acids, cannot be transported from the maternal plant to developing embryos.