Expression of two soybean resistance gene candidates shows divergence of paralogous single-copy genes

• Published in: Theoretical and applied genetics 2000-10, Vol.101 (5-6), p.789-795
• Main Authors: HAYES, A. J, YUE, Y. G, MAROOF, M. A
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Amino acids; Binding sites; Biological and medical sciences; Candidates; Cloning; Diseases and pests; DNA sequencing; Fundamental and applied biological sciences. Psychology; Gene expression; Generalities; Genes; Genetic aspects; Genetics and breeding of economic plants; Glycine max; Kinases; Lettuce; Nucleotide sequencing; Pest resistance; Physiological aspects; Plant genetics; Plant immunology; Soybean; Soybeans; Varietal selection. Specialized plant breeding, plant breeding aims
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s001220051545

The cloning of several plant genes directly involved in triggering a disease resistance response has shown that numerous resistance genes in the nucleotide binding site (NBS)/leucine-rich repeat (LRR) class have similar conserved amino acid sequences. In this study, we used a short soybean DNA sequence, previously cloned based on its conserved NBS, as a probe to identify full-length resistance gene candidates. Two homologous, but genetically independent genes were identified. One gene maps to the soybean molecular linkage group (MLG) F and a second is coded on MLG E. The first gene contains a 3,279 nucleotide open reading frame (ORF) sequence and possesses all the functional motifs characteristic of previously cloned NBS/LRR resistance genes. The N-terminal sequence of the deduced gene product is highly characteristic of other resistance genes in the subgroup of NBS/LRR genes which show homology to the Toll/Interleukin-1 receptor genes. The C-terminal region is somewhat more divergent as seen in other cloned disease resistance genes. This region of the F-linked gene contains an LRR region that is characterized by two alternatively spliced products which produce gene products with either a four-repeat or a ten-repeat LRR. The second cloned gene that maps to soybean MLG E contains 1,565 nucleotides of ORF in the N-terminal domain. Despite strong homology, however, the 3 region of this gene contains several in-frame stop codons and apparent frame shifts compared to the F-linked gene, suggesting that its functionality as a disease resistance gene is questionable. These two disease resistance gene candidates are shown to be closely related to one another and to the members of the NBS/LRR class of disease resistance genes.