Lettuce "Pretty Fast Plants" as a Teaching Tool

Nina Fedoroff (2003) called maize “man’s first and perhaps his greatest feat of genetic engineering.”  To the average student however, the stark difference between domesticated head lettuce and its wild, thorny relative, often flowering in backyard waste areas, may appear more stunning and more familiar.  Lettuce is the most widely eaten fresh vegetable in the US.  Every student in any classroom has likely eaten lettuce 1000s of times, yet lettuce, like maize, has been “genetically engineered” and domesticated lettuce looks nothing like its close wild relative.  The Composite Genome Project (CGP) has been characterizing the genetic changes associated with the domestication process and also the properties of species that make them aggressive weeds and invaders.  As part of that effort, recombinant inbred lines (RILs) generated from a cross between Salinas (crisphead) and a wild weedy accession have been produced and these are now being used as excellent teaching tools.  Scores of traits segregate in the RILs and students can choose “their” trait.  With simple excel files containing previously mapped single nucleotide polymorphisms of the RILs, students perform genome wide association studies and map their trait.  The plasticity of lettuce allows for plants to be grown in flats of 2 cm² pots and scored as seedlings or later as flowering adults.  The system provides opportunities to examine GxE interactions, map genes, characterize epistatic interactions and, with the expanding genetic resources from the CGP, follow-up studies in bioinformatics and molecular genetics.  We will describe the recent experiences using these approaches.