期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1998
卷号：95
期号：1
页码：370-375
DOI：10.1073/pnas.95.1.370
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：We used conserved domains in the major class (nucleotide binding site plus leucine-rich repeat) of dicot resistance (R) genes to isolate related gene fragments via PCR from the monocot species rice and barley. Peptide sequence comparison of dicot R genes and monocot R-like genes revealed shared motifs but provided no evidence for a monocot-specific signature. Mapping of these genes in rice and barley showed linkage to genetically characterized R genes and revealed the existence of mixed clusters, each harboring at least two highly dissimilar R-like genes. Diversity was detected intraspecifically with wide variation in copy number between varieties of a particular species. Interspecific analyses of R-like genes frequently revealed nonsyntenic map locations between the cereal species rice, barley, and foxtail millet although tight collinear gene order is a hallmark of monocot genomes. Our data suggest a dramatic rearrangement of R gene loci between related species and implies a different mechanism for nucleotide binding site plus leucine-rich repeat gene evolution compared with the rest of the monocot genome.
