Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2000
Publication Date: N/A
Interpretive Summary: New technologies have led to remarkable progress in plant scientists' understanding of the structural make-up of the genetic material of important crop plants. The more challenging task ahead now lies in determining the specific function of the thousands of individual genes, how they are controlled, and how they interact to determine the growth patterns sand overall productivity of the crop plants. From studies of novel partial hybrids we produced between the cereals oat and corn, we have obtained visual and molecular evidence that a gene known to be a control or regulating gene in corn can play a similar role when present in oat. An oat plant, into which had been added a large segment of corn genetic material that included this known regulator type gene, produced an abnormal leaf form. This leaf form had previously been shown to be associated with the corn gene functioning in a corn plant. The results demonstrate that the novel oat-corn partial hybrid plants that we developed can be a useful research tool for scientists trying to understand how genes regulate other genes and how genes interact to control growth rates and development pattern in plants. Such an understanding should help geneticists and plant breeders working to produce crop varieties that are more productive for farmers and more nutritious for consumers.
Technical Abstract: The knotted1-like class of homeobox (knox) genes are thought to be involved in meristem establishment, maintenance, and organogenesis. Ectopic expression of knox genes in homologous and heterologous plant species results in two general phenotypes: distal-to-proximal cell type transformations and the loss of apical dominance. Dominant mutations in the emaize liguleless3 (lg3) homeobox gene result in a blade (distal) -to-sheat (proximal) transformation at the midrib region of the leaf, and ectopic expression of the lg3 gene is believed to cause the phenotype. Morphological examination of a maize chromosome 3 addition line of oat revealed several phenotypes characteristic of misexpression of knox genes including: a blade-to-sheath transformation at the midrib region of the leaf, a hook-shaped panicle, and abnormal outgrowth of aerial axillary buds. Genetic analyses of an F2 family segregating for maize-chromosome 3 in oat showed that the presence of a stable maize-chromosome 3 was require for the expression of these cell fate abnormalities. We suspected that the maize lg3 gene, that is located on maize-chromosome 3, was involved in the phenotypes observed in the addition line. RNA expression analysis of leaf sheath tissue from oat plants carrying maize-chromosome 3 demonstrated that the maize lg3 gene is expressed in oat, indicating that this expression is associated with the blade-to-sheath transformation, hook-shaped panicle and outgrowth of aerial axillary bud phenotypes. Our results demonstrate that the maize addition lines of oat are useful genetic stocks to study expression of maize genes in oat.