Plant Genome IV Conference Plant Genome IV Conference
The genotype of loblolly pine clone 7-56 is heterozygous for a "null" allele at the Cad locus. Transcription of the Cad null allele is < 1% of the level of the wild type allele in haploid megagametophytes, and there is no evidence of CAD enzyme from the null allele in differentiating xylem. In progeny obtained by selfing 7-56, the xylem of 1/4 of the seedlings has a distict brown color, similar to brown midrib mutations of maize. The lignin of these seedlings is chemically different from wild-type seedlings, and the phenotypic effect is similar to that obtained with anti-sense constructs in transgenic experiments in poplar and tobacco. The wood properties and growth of seedlings with Cad null genotypes are currently under investigation and results will be presented. The Cad null gene could have implications for tree breeding.