New pepper accessions proved to be suitable as a genetic resource for use in breeding nematode-resistant rootstocks

Abstract

Root-knot nematodes (RKNs), Meloidogyne spp., are considered, worldwide, as one of the main pathogens of solanaceous crops, including pepper (Capsicum spp.). Restrictions on the use of standard nematicides have motivated the development and use of resistant cultivars and rootstocks. Three genes in pepper, called Me1, Me3 and N, confer resistance to the three main RKN species (Meloidogyne incognita, Meloidogyne javanica and Meloidogyne arenaria). However, their effectiveness seems to be limited because nematode populations that have overcome the resistance have been found, leading to a search for new sources of resistance and strategies to preserve their effectiveness. In two greenhouses and over a 7-month growing period, we evaluated the resistance to M. incognita and the agronomic behaviour as rootstocks of nine pepper (Capsicum annuum) accessions – HDA330 (Me1 carrier), Serrano Criollo de Morelos, (Me3 carrier), Yolo Wonder (partially resistant) and another six accessions of unknown resistance originating from cultivars well adapted to the local growing conditions. The resistance conferred by the Me1 gene was more robust than that conferred by Me3. Resistance to M. incognita was found in four new accessions: P13, CTL, CT5, and P14. In P13, the level of resistance was similar to that of HDA330. The resistant accessions showed better agronomic behaviour than the susceptible accessions, which was most noticeable towards the final of the growing period. Some accessions constitute a potential resource for use in the genetic breeding of RKN-resistant rootstocks.

Nematode quantitative resistance conferred by the pepper genetic background presents additive effects and is stable against different isolates of Meloidogyne incognita

“…Similarly, among inbred Me3 carrier lines, SCM was quantitatively more resistant than DH149 towards the two Me3 ‐virulent isolates, indicating the existence of resistance factors besides Me3 in the SCM genetic background. These results agree with those obtained in previous greenhouse trials with a naturally occurring Me3 ‐virulent population and avirulent population of M. incognita , where Ctl showed a high level of resistance compared to Amc, Brb and YW (Dlr was not tested), and the Me3 carrier cultivars with an SCM genetic background were more resistant than those with other backgrounds (Sánchez‐Solana et al ., ). The similarity of the results obtained in different test conditions and with different Me3 ‐virulent isolates demonstrates the broad spectrum of action of the resistance from the genetic background.…”

Host genetic resistance to root-knot nematodes,Meloidogynespp., in Solanaceae: from genes to the field

“…sweet potato, cotton, soybean and peanut, and none in the Solanaceae. Very recently, quantitative resistance to RKNs was detected in some pepper accessions . A QTL analysis for resistance to the three main RKN species, M. incognita , M. arenaria and M. javanica , in a cross between a partially resistant and a susceptible pepper line yielded four new QTLs localised on two separate clusters: three QTLs clustered on chromosome P1 with each active against one of the three RKN species, and one QTL active against M. javanica on chromosome P9 (Barbary et al , unpublished).…”

“…In cases where RKN‐resistant elite cultivars are not commercially available, grafting plants on resistant rootstocks has been considered as a possible alternative, with the additional advantage that grafting may improve tolerance of vegetables to abiotic stresses . For example, in south‐eastern Spain, under greenhouse crop conditions, a close relationship was found between pepper rootstock resistance to M. incognita and yield, the more resistant accessions showing the better agronomic performance as rootstocks . However, for some of the resistant genotypes tested, two successive years of growing grafted plants in a naturally M. incognita ‐infested greenhouse was sufficient to overcome resistance, which again highlights the need for careful management of such genetic resources.…”

Effectiveness of quantitative resistance conferred by the genetic background of pepper in the control of root‐knot nematodes and influence onto durability of Me1‐ and Me3‐resistant genes in greenhouse conditions

“…However, this nematode develops virulent populations against Me3 and N genes in plants carrying the same gene when cultivation is repeated in the same soil (Ros‐Ibáñez, Robertson, Martínez‐Lluch, Cano‐García, & Lacasa‐Plasencia, ; Thies, ). To date, only the Me1 gene has been shown to be a durable source of resistance (Barbary et al., ; Sánchez‐Solana, Ros, Guerrero et al., ).…”

“…Pathogen populations tend to be highly heterogeneous and may show several generations during the same growing season. In previous assessments in greenhouses of the Campo de Cartagena (Murcia, Spain), some varieties of peppers with quantitative resistance showed satisfactory results in the control of M. incognita, using the plants as rootstock (S anchez-Solana, Ros, Guerrero et al, 2016;. However, in these conditions, their effects for preserving the effectiveness of R-genes are unknown.…”