High resolution genetic and physical mapping of the I-3 region of tomato chromosome 7 reveals almost continuous microsynteny with grape chromosome 12 but interspersed microsynteny with duplications on Arabidopsis chromosomes 1, 2 and 3.
The tomato I-3 gene introgressed from the Lycopersicon pennellii accession LA716 confers resistance to race 3 of the fusarium wilt pathogen Fusarium oxysporum f. sp. lycopersici. We have improved the high-resolution map of the I-3 region of tomato chromosome 7 with the development and mapping of 31 new PCR-based markers. Recombinants recovered from L. esculentum cv. M82 x IL7-2 F2 and (IL7-2 x IL7-4) x M82 TC1F2 mapping populations, together with recombinants recovered from a previous M82 x IL7-3 F2 mapping population, were used to position these markers. A significantly higher recombination frequency was observed in the (IL7-2 x IL7-4) x M82 TC1F2 mapping population based on a reconstituted L. pennellii chromosome 7 compared to the other two mapping populations based on smaller segments of L. pennellii chromosome 7. A BAC contig consisting of L. esculentum cv. Heinz 1706 BACs covering the I-3 region has also been established. The new high-resolution map places the I-3 gene within a 0.38 cM interval between the molecular markers RGA332 and bP23/gPT with an estimated physical size of 50-60 kb. The I-3 region was found to display almost continuous microsynteny with grape chromosome 12 but interspersed microsynteny with Arabidopsis thaliana chromosomes 1, 2 and 3. An S-receptor-like kinase gene family present in the I-3 region of tomato chromosome 7 was found to be present in the microsyntenous region of grape chromosome 12 but was absent altogether from the A. thaliana genome.
Lim
G T T
GT
Plant Cell Biology, Research School of Biological Sciences, The Australian National University, Canberra, ACT, 0200, Australia.
Wang
G-P
GP
Hemming
M N
MN
McGrath
D J
DJ
Jones
D A
DA
D017360:Arabidopsis / Q000235:genetics*; D022202:Chromosomes, Artificial, Bacterial; D032461:Chromosomes, Plant; D018744:DNA, Plant / Q000235:genetics; D005819:Genetic Markers; D018745:Genome, Plant; D018551:Solanum lycopersicum / Q000235:genetics*; D020161:Physical Chromosome Mapping; D017422:Sequence Analysis, DNA; D026801:Synteny; D027843:Vitis / Q000235:genetics*
D018744:DNA, Plant; D005819:Genetic Markers