Regulation of gene expression during conifer embryogenesis

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Clonal propagation by somatic embryogenesis (SE) has the potential for the delivery of superior material to the commercial forest in a much shorter time and used in combination with the sexual process for seed production will help maintain the correct genetic balance from seed orchards. Presently constraints to the successful introduction of commercial embryogenesis in conifers are perceived to be: a) improvement of embryo quality; b) efficiency and the number of responding genotypes; c) induction of SE from mature tissues. To develop SE for white spruce and Douglas fir, two economically important species in Canada, we have been examining the molecular events during development of SE and ZE. The analysis of cDNA and genomic sequences expressed during maturation have provided important information on molecular biology of conifer embryo maturation and form the basis of continuing proposed studies that will focus on very early stages of embryogeny. The molecular basis of early embryogeny, role of MG, suspensor, and other factors in self- and cross-pollinated seeds will be studied using the homologous embryo regulatory probes (transcription factor PmLEC1, and PmCOP1, two critical genes expressed during early Douglas fir ZE and SE, (isolated in my lab), and DD-PCR. The functional analysis of these genes will be performed by reverse genetics. In addition, differences between E and NE cultures during the induction phase will be examined to understand what roles the gene products play in initiation of SE. Formation of conifer E culture is genotype dependent and induction frequencies can vary widely among families. Approaches include PCR based SSH cDNA libraries coupled with microarray and/or quantitative RT-PCR based profile analyses. Microarray based methodology will allow the simultaneous quantification of a large number of transcripts to identify coordinated gene groups during SE initiation and response (s) to PGRs including Brassinolide treatment implicated in increased SE frequency from a wide range of genotypes of conifers, including Douglas fir. The research is of fundamental and practical interest and will also be important in training of HQP.