Identifikasi fragment CDNA yang berpautan dengan lokus NV dan TM-2 pada tomat

Abstract

Tm-2 is a resistance gene in tomato to Tomato Mosaic Virus (ToMV), located in heterochromatic region of chromosome nine.Since map based cloning difficult to perform for identify the gene on that region, we apply differential display approach by using two near-isogenic tomato lines (NILs), one without Tm-2 and the other with Tm-2 to identify cDNAs of the transcripts from the region surrounding the Tm-2 locus. Among the 1SO combinations of three anchor primers and fifty arbitrary primers, 10 combinations generated cDNA poly­ morphic bands. Out of them, only one combination of CA6, exhibited .poly­ morphic band under southern blot analysis, subsequently a genetic ex­ periment showed that the CA6 locus tightly linked to the Tm-2 locus. The CA6 fragment also hybridized to genomic DNA fragments from a tomato line canying Tm-2a, a line of L. peruvianum from which Tm-2a originated, and a tomato line canying another Tm-2-like gene. A northern hybridization• blotting result suggested that the gene corre­ sponding to CA6 fragment was constitu­ tively transcribed.