Low genetic diversity makes peanut （Arachis hypogaea L.） very vulnerable to plant pathogens, causing severe yield loss and reduced seed quality. Several hundred partial genomic DNA sequences as nucleotide-binding-si...Low genetic diversity makes peanut （Arachis hypogaea L.） very vulnerable to plant pathogens, causing severe yield loss and reduced seed quality. Several hundred partial genomic DNA sequences as nucleotide-binding-site leucine-rich repeat （NBS-LRR） resistance genes （R） have been identified, but a small portion with expressed transcripts has been found. We aimed to identify resistance gene analogs （RGAs） from peanut expressed sequence tags （ESTs） and to develop polymorphic markers. The protein sequences of 54 known R genes were used to identify homologs from peanut ESTs from public databases. A total of 1,053 ESTs corresponding to six different classes of known R genes were recovered, and assembled 156 contigs and 229 singletons as peanut-expressed RGAs. There were 69 that encoded for NBS-LRR proteins, 191 that encoded for protein kinases, 82 that encoded for LRR-PK/transmembrane proteins, 28 that encoded for Toxin reductases, 11 that encoded for LRR-domain containing proteins and four that encoded for TM-domain containing proteins. Twenty-eight simple sequence repeats （SSRs） were identified from 25 peanut expressed RGAs. One SSR polymorphic marker （RGA121） was identified. Two polymerase chain reaction-based markers （Ahsw-1 and Ahsw-2） developed from RGA013 were homologous to the Tomato Spotted Wilt Virus （TSWV） resistance gene. All three markers were mapped on the same linkage group AhIV. These expressed RGAs are the source for RGA-tagged marker development and identification of peanut resistance genes.展开更多
Peanut （Arachis hypogaea; 2n = 4x = 40） is a nutritious food and a good source of vitamins, minerals, and healthy fats. Expansion of genetic and genomic resources for genetic enhancement of cultivated peanut has gai...Peanut （Arachis hypogaea; 2n = 4x = 40） is a nutritious food and a good source of vitamins, minerals, and healthy fats. Expansion of genetic and genomic resources for genetic enhancement of cultivated peanut has gained momentum from the sequenced genomes of the diploid ancestors of cultivated peanut. To facil- itate high-throughput genotyping of Arachis species, 20 genotypes were re-sequenced and genome-wide single nucleotide poiymorphisms （SNPs） were selected to develop a large-scale SNP genotyping array. For flexibility in genotyping applications, SNPs polymorphic between tetraploid and diploid species were included for use in cultivated and interspecific populations. A set of 384 accessions was used to test the array resulting in 54 564 markers that produced high-quality polymorphic clusters between diploid species, 47 116 polymorphic markers between cultivated and interspecific hybrids, and 15 897 polymorphic markers within A. hypogaea germplasm. An additional 1193 markers were identified that illuminated genomic re- gions exhibiting tetrasomic recombination. Furthermore, a set of elite cultivars that make up the pedigree of US runner germplasm were genotyped and used to identify genomic regions that have undergone pos- itive selection. These observations provide key insights on the inclusion of new genetic diversity in culti- vated peanut and will inform the development of high-resolution mapping populations. Due to its efficiency, scope, and flexibility, the newly developed SNP array will be very useful for further genetic and breeding applications in Arachis.展开更多
基金supported by funds provided by the Georgia Agricultural Commodity Commission for Peanuts,the National Peanut Board and the Peanut Foundation
文摘Low genetic diversity makes peanut （Arachis hypogaea L.） very vulnerable to plant pathogens, causing severe yield loss and reduced seed quality. Several hundred partial genomic DNA sequences as nucleotide-binding-site leucine-rich repeat （NBS-LRR） resistance genes （R） have been identified, but a small portion with expressed transcripts has been found. We aimed to identify resistance gene analogs （RGAs） from peanut expressed sequence tags （ESTs） and to develop polymorphic markers. The protein sequences of 54 known R genes were used to identify homologs from peanut ESTs from public databases. A total of 1,053 ESTs corresponding to six different classes of known R genes were recovered, and assembled 156 contigs and 229 singletons as peanut-expressed RGAs. There were 69 that encoded for NBS-LRR proteins, 191 that encoded for protein kinases, 82 that encoded for LRR-PK/transmembrane proteins, 28 that encoded for Toxin reductases, 11 that encoded for LRR-domain containing proteins and four that encoded for TM-domain containing proteins. Twenty-eight simple sequence repeats （SSRs） were identified from 25 peanut expressed RGAs. One SSR polymorphic marker （RGA121） was identified. Two polymerase chain reaction-based markers （Ahsw-1 and Ahsw-2） developed from RGA013 were homologous to the Tomato Spotted Wilt Virus （TSWV） resistance gene. All three markers were mapped on the same linkage group AhIV. These expressed RGAs are the source for RGA-tagged marker development and identification of peanut resistance genes.
文摘Peanut （Arachis hypogaea; 2n = 4x = 40） is a nutritious food and a good source of vitamins, minerals, and healthy fats. Expansion of genetic and genomic resources for genetic enhancement of cultivated peanut has gained momentum from the sequenced genomes of the diploid ancestors of cultivated peanut. To facil- itate high-throughput genotyping of Arachis species, 20 genotypes were re-sequenced and genome-wide single nucleotide poiymorphisms （SNPs） were selected to develop a large-scale SNP genotyping array. For flexibility in genotyping applications, SNPs polymorphic between tetraploid and diploid species were included for use in cultivated and interspecific populations. A set of 384 accessions was used to test the array resulting in 54 564 markers that produced high-quality polymorphic clusters between diploid species, 47 116 polymorphic markers between cultivated and interspecific hybrids, and 15 897 polymorphic markers within A. hypogaea germplasm. An additional 1193 markers were identified that illuminated genomic re- gions exhibiting tetrasomic recombination. Furthermore, a set of elite cultivars that make up the pedigree of US runner germplasm were genotyped and used to identify genomic regions that have undergone pos- itive selection. These observations provide key insights on the inclusion of new genetic diversity in culti- vated peanut and will inform the development of high-resolution mapping populations. Due to its efficiency, scope, and flexibility, the newly developed SNP array will be very useful for further genetic and breeding applications in Arachis.
