Theoretical and Applied Genetics (2003) 106, 478-484

J.S.S. Ammiraju, J.C. Veremis, X. Huang, P.A. Roberts and I. Kaloshian (2003)
The heat-stable root-knot nematode resistance gene Mi-9 from Lycopersicon peruvianum is localized on the short arm of chromosome 6
Theoretical and Applied Genetics 106 (3), 478-484
Abstract: The tomato gene Mi-1 confers resistance to three species of root-knot nematodes, Meloidogyne spp. However, the resistance mediated by Mi-1 is inactive at soil temperatures above 28 °C. Previously, we identified and mapped a novel heat-stable nematode resistance gene from the wild species Lycopersicon peruvianum accession LA2157 on to chromosome 6. Here we report further characterization of this heat-stable resistance against three Mi-1-avirulent biotypes of Meloidogyne javanica, Meloidogyne arenaria and Meloidogyne incognita. Screening segregating F₂ and F₃ progenies, derived from an intraspecific cross between susceptible LA392 and resistant LA2157, for nematode resistance at 25 °C and 32 °C, revealed a simple dominant monogenic inheritance with all the biotypes tested. We designate this gene as Mi-9. As a first step towards cloning of Mi-9, we constructed a linkage map around this gene. A total of 216 F₂ progeny from the cross between LA392 and LA2157 were screened with M. javanica at 32 °C and with CT119 and Aps-1, markers that flank the genetic interval that contains the Mi-1 gene. DNA marker analysis indicated that these markers also flank Mi-9. Further mapping of recombinants with both RFLP and PCR-based markers localized Mi-9 to the short arm of chromosome 6 and within the same genetic interval that spans the Mi-1 region.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Philip A. Roberts

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Meloidogyne javanica	Tomato (Solanum lycopersicum)
	Meloidogyne incognita	Tomato (Solanum lycopersicum)
	Meloidogyne arenaria	Tomato (Solanum lycopersicum)