Development of virulence to Meloidogyne incognita on resistant pepper rootstocks

C Ros Ibáñez,Maria Del Carmen Martinez-Lluch,Ana Cano-García,Lee Robertson,Alfredo Lacasa-Plasencia

doi:10.5424/sjar/2014121-4340

Abstract

The root-knot nematode (RKN) Meloidogyne incognita is a major soil parasite of pepper crops in greenhouses in Southeast Spain. Due to the limitations of the use of soil fumigants, grafting plants on resistant rootstocks (R-rootstocks) has become an important alternative to chemical nematicides. The repeated use of R-rootstocks can bring about the selection of virulent populations capable of overcoming resistance. We carried out a six-year investigation on resistant rootstocks in a naturally M. incognita infested greenhouse, and found that two successive years of growing plants grafted on R-rootstocks Atlante (ATL) were sufficient to overcome resistance (galling index 1.5 and 5.6 in the first and second years respectively). A large variability was observed between several R-rootstocks. Two R-rootstocks (C19 and Snooker) behaved like ATL while two others (Terrano and DRO 8801) were not infected by RKN. Laboratory studies with the same R-rootstocks, inoculated with two nematode isolates (avirulent and virulent against ATL) confirmed the greenhouse results, indicating that some rootstocks may be infested by virulent populations and others may not. It suggests that different R-genes, which are differentially overcome by RKN, have been introgressed into the rootstocks. This may have consequences for the management of resistant rootstocks in the field.

Highlights

Nematodes of the genus Meloidogyne are obligate endoparasites of more than 5,500 plant species (Goodey et al, 1965)
Meloidogyne incognita is distributed throughout temperate and tropical areas and is considered the main plant-parasitic nematode on a global scale (Lamberti, 1981; Trudgill & Blok, 2001) and is, together with M. javanica and M. arenaria, the predominant species in Spain (Bello et al, 2004; Giné et al, 2012; VerdejoLucas et al, 2012)
This paper presents the results of investigations carried out in M. incognita-infested greenhouses to study the development of virulence in nematode populations after the repeated cultivation of resistant pepper rootstocks

Summary

Introduction

Nematodes of the genus Meloidogyne are obligate endoparasites of more than 5,500 plant species (Goodey et al, 1965). Meloidogyne incognita is distributed throughout temperate and tropical areas and is considered the main plant-parasitic nematode on a global scale (Lamberti, 1981; Trudgill & Blok, 2001) and is, together with M. javanica and M. arenaria, the predominant species in Spain (Bello et al, 2004; Giné et al, 2012; VerdejoLucas et al, 2012). Both M. incognita and M. arenaria are found on protected and non-protected crops in central and southern Spain (Bello et al, 2004; LópezPérez et al, 2011), and only on protected crops close to the Atlantic coast. M. hapla is found in the northern regions of Spain and M. javanica is mainly found in the eastern and south-eastern regions (Verdejo-Lucas et al, 2002; Robertson et al, 2006)

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Conclusion