Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 1/1/2002
Publication Date: 1/1/2002
Citation: CHAUHAN, R.S., LEONG, S.A. GENOMICS OF DISEASE RESISTANCE LOCI IN CEREALS. RECENT RESEARCH DEVELOPMENTS IN GENETICS. 2002. v. 2. p. 1-29.
Technical Abstract: Nine resistance (R) genes have been cloned in rice, barley, and maize out of three dozen R genes cloned in other crop plants including Arabidopsis. Two of the nine genes, mlo and Hm1 in barley and maize, respectively, do not belong to any characterized family of R genes. Many resistance gene analogs (RGAs) have been cloned from different cereals and some of those map as single genes or in clusters to locations associated with genetically characterized R genes in different genomes. Colinearity-a hallmark of cereal genomes seems to be lost for RGAs as well as R genes across different grass genomes, implying that R genes are evolving and rearranging rapidly compared to other loci. Molecular genetic evidence is accumulating for a role of mutation followed by diversifying selection as well as recombination between alleles and sometimes between gene family members, in creating novel recognition specificities. Cloning of pathogen avirulence genes is expected to help in predicting durability of R genes as well as identifying novel R genes across different genomes.