ARS | Publication request: Expanding the boundaries of gene variation for crop improvement

Submitted to: Meeting Proceedings
Publication Type: Proceedings/Symposium
Publication Acceptance Date: August 12, 2008
Publication Date: N/A

Technical Abstract: Directed and undirected mutagenesis continues to offer unique opportunities for crop improvement. Mutations also occur naturally and different forms are present in each strain of plants within and among species. Modifying genes affect the expression of all mutants, and examples exist where the deleterious features of a mutant can be significantly changed by selection. New technologies, including those associated with genomics such as resequencing, TILLING, and RNA interference, allow the detection of gene variation at an unprecedented frequency. Knowledge of genes that affect recombination among homoeologous chromosomes may lead to inducible methods regulating the exchange among chromosomes in a polyploid species. Forward and reverse genetic methods are readily available in many species, including model plant species. There are an estimated one million sites in the japonica rice genome tagged via Tos17, Ac/Ds, T-DNA, and other insertion elements. Site-specific mutagenesis and gene replacement methods may replace the need for transgenic technology in some cases. Transcriptome modification occurs via mutagen treatment, aneuploidy, and uniparental chromosome loss, and sometimes results in a mutant phenotype. Novel mutant types produced by interspecific sexual crosses are described from maize chromosome and chromosome segment additions to oat. The boundaries of gene variation appear to be more expansive as plant genetics knowledge and technologies increase.