Tissue-specific gene expression in tomato and tobacco.

摘要

Floral morphogenesis and fruit developement are models of developmental regulation of plant gene expression. Both processes comprise major aspects of plant development: cellular differentiation, organogenesis, differential cell division and spatial and temporal regulation of gene expression. Changes in RNA and protein synthesis in the plant apex during transition and maturation of the flower and during early fruit development suggest that changes in gene expression are intimately involved in the determination and maturation of floral and fruit tissues and organs. Many genes are differentially regulated during these processes, and our laboratory has focused primarily on genes that are active during anther development and genes active during early fruit development.; In chapter one, degenerate primers were used to PCR-amplify genes active in anthers during pollen development. One gene from this amplification (ntGRP15) was sequenced, analyzed and compared to other genes known to be expressed during flower morphogenesis. ntGRP15 is a stringently regulated gene, active during meiosis to the free microspore stages of anther development. The protein encoded by the ntGRP15 locus appears to be a structural cell wall protein.; Chapter two investigations were undertaken as the result of previous research that suggested sucrose synthase is a biochemical marker for sink strength during early tomato fruit development. It was determined that the cloned promoter contains signals for organ-specific expression of GUS in transgenic tomato plants but that sequences other than the cloned promotor are required for proper spatial and temporal expression of GUS in transgenic tomato plants. However, those sequences or sequence motifs necessary for vascular localization are contained within the cloned promotor. The intron is not required for the vascular localization of sucrose synthase, but is important in the repression of ectopic sucrose synthase expression.; The third chapter is a phylogenetic analysis of sucrose synthase genes in higher plants. Alignment and subsequent parsimony analysis of the sucrose synthase protein sequences, when compared to the species relationships suggest that there have been five independent gene duplication events and two independent losses at the loci since the monocot-dicot divergence approximately 200 MYA.