Duplication-Resistant Genes: Why Are They Single-Copy?

‘Duplication-resistant’ (DR) genes, that persist as single-copy genes in a variety of plant genomes after multiple shared or independent whole genome duplication events, may offer insight into the unsolved evolutionary question about non-random gene loss after duplication. Some common characteristics shared by this group of genes include shorter than average proteins, more introns, and enrichment in gene functional categories such as chloroplast, mitochondrion, and DNA/RNA metabolism. Yet, more needs to be known to understand why plants consistently and repeatedly restrict these particular genes to single copy status. As one of several approaches to study their roles in plant growth and development, here we summarize results from T-DNA knockout lines of Arabidopsis thaliana. More than 150 knockout lines of Arabidopsis candidate DR genes have been screened under standard lab conditions as well as about ten stressed conditions. It is found that the chance of observing an abnormal phenotype in the DR candidates’ knockouts is higher than for average Arabidopsis genes, indicating that DR genes might be more important than random genes. Meanwhile, we are creating overexpression/addition lines, representing plants with many copies and four copies of DR genes, respectively, to investigate potential negative effects to plants that are caused by the duplicated status of DR genes.