Isolamento de análogos de genes de resistência (RGAs) em arachis cardernasii

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Wild species of Arachis have been characterized by their high level of genetic polymorphism. Included among these species is Arachis cardenasii that is well known for showing resistances to different diseases. The gene products that are responsable for the resistance to various species of plants have conserved domains, and these domains can be used as molecular markers to aid in the isolation of resistance genes. This study had the objective of isolating of RGAs (resistance gene analogues) from wild Arachis species. Degenerate primers were designed to amplify the regions of conserved NBS (nucleotide binding site) motifs by PCR (polimerase chain reaction). The motifs used to design the primers were P-loop, GLPL and RNBS-D. The vector pGEM-T was used to clone the amplified fragments and the reults of ligation were introduced into the bacteria Escherichia coli by eletroporation. 656 DNA fragments were sequenced and searched using the program Blast to verify the homology to Arabidopsis thaliana sequences in a local data base. Among these sequences, 142 were classified as RGAs, and various retroelements were also identified. The primer combinations used enabled the isolation of subclasses classified as TIR and non TIR-NBS. Non TIR sequences could be amplified using the primer based on the motif RNBS-D that is specific to the non TIR subclass. The RGAs were analised by the Staden Package Program to form the contigs and to edit the consensus sequences. These sequences were put in the Arachis RGAs data base and in GenBank. These RGAs will be used as molecular markers in peanut (Arachis hypogaea) breeding programs and as an auxilary tool to isolate R genes be used in transgenic approaches.

ASSUNTO(S)

amendoim ciências biológicas arachis cardenasii genes genética vegetal plantas -resistência à doenças e pragas plantas - melhoramento genético rgas

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