title: Comparative analysis of resistance gene analogues encoding NBS-LRR domains in cotton.
abstract: BACKGROUND
  Plant production is severely affected by biotic and abiotic stresses R-genes exhibit resistance against a range of diseases and pathogens in plants. The nucleotide binding site and leucine rich repeat (NBS-LRR) class of R-genes is the most comprehensively studied in terms of sequence evolution and genome distribution. The differential response for resistance against biotic and abiotic stress has been observed in cultivated and wild relatives of the genus Gossypium.
  
  
  RESULTS
  Efforts have been made to address the recent evolution of NBS-LRR sequences within Gossypium hirsutum and resistance gene analogue (RGA) sequences derived from G. arboreum and G. raimondii. The % identity and phylogenetic analysis of NBS-LRR-encoded RGAs from tetraploid New World cotton and its diploid ancestors G. raimondii and G. arboreum suggest that the evolution of NBS-LRR-encoding sequences in G. hirsutum occurred by gradual accumulation of mutants that led to positive selection and a slow rate of divergence within distinct R-gene families.
  
  
  CONCLUSIONS
  The allotetraploid genome of cotton, after separating from its diploid parents, experienced polyploidisation, natural and artificial selection, hybrid necrosis, duplication and recombination which became the reason to shed off and evolve new genes for its survival. These driving forces influenced the development of genomic architecture that make it susceptible to diseases and pathogens as compared to donor parents.
authors: Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan.
authors: Abdul Manan
authors: AM
authors: Khan
authors: Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan.
authors: Asif Ali
authors: AA
authors: Khan
authors: Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan.
authors: Muhammad Tehseen
authors: MT
authors: Azhar
authors: Department of Plant Pathology, University of Agriculture, Faisalabad, Faisalabad, Pakistan.
authors: Luqman
authors: L
authors: Amrao
authors: Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad, Pakistan.
authors: Hafiza Masooma Naseer
authors: HM
authors: Cheema
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics*; D019143:Evolution, Molecular; D017343:Genes, Plant / Q000235:genetics; D003368:Gossypium / Q000235:genetics*; D007930:Leucine / Q000235:genetics*; D009711:Nucleotides / Q000378:metabolism*; D010802:Phylogeny; D012091:Repetitive Sequences, Nucleic Acid; D012641:Selection, Genetic; D017385:Sequence Homology; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
chemical_list: D009711:Nucleotides; D007930:Leucine
keywords: Gossypium spp; NBS-LRR domain; disease resistance; resistance gene analogues