A large scale analysis of resistance gene homologues in Arachis

Abstract

Arachis hypogaea L., commonly known as the peanut or groundnut, is an important and widespread food legume. Because the crop has a narrow genetic base, genetic diversity in A. hypogaea is low and it lacks sources of resistance to many pests and diseases. In contrast, wild diploid Arachis species are genetically diverse and are rich sources of disease resistance genes. The majority of known plant disease resistance genes encode proteins with a nucleotide binding site domain (NBS). In this study, degenerate PCR primers designed to bind to DNA regions encoding conserved motifs within this domain were used to amplify NBS-encoding regions from Arachis spp. The Arachis spp. used were A. hypogaea var. Tatu and wild species that are known to be sources of disease resistance: A. cardenasii, A. duranensis, A. stenosperma and A. simpsonii. A total of 78 complete NBS-encoding regions were isolated, of which 63 had uninterrupted ORFs. Phylogenetic analysis of the Arachis NBS sequences derived in this study and other NBS sequences from Arabidopsis thaliana, Medicago trunculata, Glycine max, Lotus japonicus and Phaseolus vulgaris that are available in public databases This analysis indicates that most Arachis NBS sequences fall within legume-specific clades, some of which appear to have undergone extensive copy number expansions in the legumes. In addition, NBS motifs from A. thaliana and legumes were characterized. Differences in the TIR and non-TIR motifs were identified. The likely effect of these differences on the amplification of NBS-encoding sequences by PCR is discussed.

Lathyrus improvement for resistance against biotic and abiotic stresses: From classical breeding to marker assisted selection

“…However, more recently, the cloning of several major resistance genes and recognition of its conserved domains provided the methodology to directly identify resistance genes analogs in several plant species, including a number of legumes (soybean (Kanazin et al, 1996;Yu et al, 1996), alfalfa (Cordero & Skinner, 2002), common bean (Creusot et al, 1999;Rivkin et al, 1999), pea (Timmerman-Vaughan et al, 2000), cowpea (Gowda et al, 2002), peanut (Bertioli et al, 2003) and lentils (Yaish et al, 2004)). This approach attempts to identify genomic regions likely to contain resistance genes and it could be extremely useful on species like grass pea where the level of saturation in the existing genomic maps is still far from the desirable to start the map-based cloning of resistance genes.…”

Marker‐Assisted Selection for Biotic Stress Resistance in Peanut

“…Using such primers, RGAs have been identified from wild and cultivated peanut. Seventy-eight nonredundant NBS-encoding regions were characterized by Bertioli et al (2003). Phylogenetic analysis of these sequences with NBS encoding sequences from Arabidopsis thaliana, Medicago truncatula, Glycine max, Lotus japonicus, and Phaseolus vulgaris showed that most Arachis NBS sequences fall within legumespecific clades, and that sequences in some clades appear to have undergone extensive copy number expansions in the legumes.…”

Cloning and Characterization of a NBS-LRR Resistance Gene from Peanut (Arachis hypogaea L.?

“…The quality and concentration of DNA was measured with the electrophoresis and spectrophotometer. As shown in Table 1, degenerate primers were designed based on amino acid sequences MGGVGKT and GLPLALK of proteinic conserved domains P-loop and GLPL respectively, which were coded by resistance genes of NBS structural domains (Bertioli et al, 2003). Cycling conditions were as follows: The template was denatured at 94°C for 5 min; 35 cycles of 94°C for 1 min, 58°C for 1 min, 72°C for 90 s; followed by 10 min at 72°C.…”

“…The identified mechanism included cell wall thickening, resistance gene (R gene) expression and apoptosis. Current studies are focusing on R genes cloning (Bertioli et al, 2003). The genetic analysis of genetic resistance to rust and flax rust fungus pathogenicity made it the first time to recognize the gene for gene interaction theory (Jeff et al, 2000).…”