title: Mi-1-Mediated Nematode Resistance in Tomatoes is Broken by Short-Term Heat Stress but Recovers Over Time.
abstract: Tomato (Solanum lycopersicum L.) is among the most valuable agricultural products, but Meloidogyne spp. (root-knot nematode) infestations result in serious crop losses. In tomato, resistance to root-knot nematodes is controlled by the gene Mi-1, but heat stress interferes with Mi-1-associated resistance. Inconsistent results in published field and greenhouse experiments led us to test the effect of short-term midday heat stress on tomato susceptibility to Meloidogyne incognita race 1. Under controlled day/night temperatures of 25°C/21°C, 'Amelia', which was verified as possessing the Mi-1 gene, was deemed resistant (4.1 ± 0.4 galls/plant) and Rutgers, which does not possess the Mi-1 gene, was susceptible (132 ± 9.9 galls/plant) to M. incognita infection. Exposure to a single 3 hr heat spike of 35°C was sufficient to increase the susceptibility of 'Amelia' but did not affect Rutgers. Despite this change in resistance, Mi-1 gene expression was not affected by heat treatment, or nematode infection. The heat-induced breakdown of Mi-1 resistance in 'Amelia' did recover with time regardless of additional heat exposures and M. incognita infection. These findings would aid in the development of management strategies to protect the tomato crop at times of heightened M. incognita susceptibility.
authors.affiliation: EMBRAPA Coastal Tablelands, Aracaju-SE, Brazil. ; These authors contributed equally to this work.
authors.forename: Luciana
authors.initials: L
authors.lastname: Marques de Carvalho
authors.affiliation: Entomology and Nematology Department, University of Florida, Gainesville, FL. ; These authors contributed equally to this work.
authors.forename: Nicole D
authors.initials: ND
authors.lastname: Benda
authors.affiliation: National Center for Agricultural Utilization Research USDA-ARS, Peoria, IL.
authors.forename: Martha M
authors.initials: MM
authors.lastname: Vaughan
authors.affiliation: Entomology and Nematology Department, University of Florida, Gainesville, FL.
authors.forename: Ana R
authors.initials: AR
authors.lastname: Cabrera
authors.affiliation: Center for Medical and Veterinary Entomology USDA-ARS, Gainesville, FL.
authors.forename: Kaddie
authors.initials: K
authors.lastname: Hung
authors.affiliation: Center for Medical and Veterinary Entomology USDA-ARS, Gainesville, FL.
authors.forename: Thomas
authors.initials: T
authors.lastname: Cox
authors.affiliation: Area Directors Office USDA-ARS, Athens, GA.
authors.forename: Zaid
authors.initials: Z
authors.lastname: Abdo
authors.affiliation: Center for Medical and Veterinary Entomology USDA-ARS, Gainesville, FL.
authors.forename: L Hartwell
authors.initials: LH
authors.lastname: Allen
authors.affiliation: Center for Medical and Veterinary Entomology USDA-ARS, Gainesville, FL.
authors.forename: Peter E A
authors.initials: PE
authors.lastname: Teal
keywords: Meloidogyne incognita; Mi-1 gene; Solanum lycopersicum; heat stress; resistance; root-knot nematode