Crop rotation with Meloidogyne-resistant germplasm is useful to manage and revert the (a)virulent populations of Mi1.2 gene and reduce yield losses

Abstract

A rotation sequence of ungrafted and grafted tomato-melon-pepper-watermelon on resistant rootstocks ‘Brigeor’, Cucumis metuliferus, ‘Oscos’ and Citrullus amarus, respectively, was carried out in a plastic greenhouse, ending with a susceptible or resistant tomato crop. The rotation was conducted in plots infested by an avirulent (Avi) or a partially virulent (Vi) Meloidogyne incognita population to the Mi1.2 gene. At the beginning of the study, the reproduction index (RI, relative reproduction in the resistant respect susceptible tomato) of Avi and Vi populations was 1.3% and 21.6%, respectively. Soil nematode density at transplanting (Pi) and at the end (Pf) of each crop, disease severity and crop yield were determined. Moreover, the putative virulence selection and fitness cost were determined at the end of each crop in pot tests. In addition, a histopathological study was carried out 15 days after nematode inoculation in pot test. The volume and number of nuclei per giant cell (GC) and the number of GC, their volume and the number of nuclei per feeding site in susceptible watermelon and pepper were compared with C. amarus and resistant pepper. At the beginning of the study, the Pi of Avi and Vi plots did not differ between susceptible and resistant germplasm. At the end of the rotation, the Pf of Avi was 1.2 the Pi in susceptible and 0.06 in resistant, the cumulative yield of grafted crops was 1.82 times higher than that of the ungrafted susceptible ones, and the RI in resistant tomato less than 10% irrespective of the rotation sequence. Concerning the Vi, Pf was below the detection level at the end of the rotation in resistant and 3 times Pi in the susceptible. The cumulative yield of grafted crops was 2.83 times higher than that of the ungrafted and the RI in resistant tomato was 7.6%, losing the population’s virulence. In the histopathological study, no differences in number of GC per feeding site were observed in watermelon compared to C. amarus, but they were more voluminous and contained higher number of nuclei per GC and per feeding site. Regarding pepper, Avi population did not penetrate resistant rootstock.

Host Suitability of Lettuce and Bean Germplasm for Meloidogyne incognita and M. javanica Isolates from Spain

“…In short, this study contributes to provide information on lettuce and bean germplasm able to reduce M. incognita and M. javanica to be included in a crop rotation sequence as an alternative to chemical control. Moreover, the inclusion of different resistance genes in crop rotation sequences can contribute to the durability of each single resistance gene despite having been previously selected for their virulence to a specific resistance gene [ 12 , 38 ]. Furthermore, if selection for virulence of a given specific resistance gene did occur, it would not compromise other resistance genes [ 39 ].…”

“…Also, the repeated cultivation of resistant tomato cultivars carrying the Mi 1.2 gene may allow for the development of virulent RKN populations or species [ 9 , 10 , 11 ]. The effectiveness and durability of a given resistance source can be maximized if it is included in rotation sequences with plants carrying different resistance genes and/or with non- or poor hosts [ 12 ]. The host status of a given plant to a given nematode species is defined by the relationship between the nematode densities at the end of the crop or experiment ( Pf ) and the nematode densities at the beginning of the crop or experiment ( Pi ) [ 13 , 14 ].…”

Upgrading Strategies for Managing Nematode Pests on Profitable Crops

“…Moreover, recently published greenhouse tests demonstrated that grafting may alleviate the problems of these pathotypes. New rotation sequences of grafted tomato-melon-pepper-watermelon on resistant rootstocks could revert the virulent Meloidogyne incognita populations on the Mi1.2 gene and consequently minimize yield losses compared to ungrafted plants [ 37 ]. Using resistant rootstocks, both intra- and interspecies grafting can provide safe and effective alternatives to choose and apply desirable PPN resistance trait in cultivated vegetables, whether in open-field or protected conditions.…”

“…A better grasp of the nature of PPN–host interactions that regulate plant susceptibility/resistance can boost the discovery and use of PPN-resistant genes. Also, expansion of metagenomic tools and artificial intelligence for emerging PPN control plans will supply stakeholders with swifter, more accurate PPN identification and decision tools by properly revealing the food web in the plant rhizosphere and the exact mechanisms underlying PPN-suppressive soils [ 13 , 25 , 37 , 39 , 52 ].…”

Identification and Characterization of a Virulent Meloidogyne incognita Population Breaking Tomato Mi-1-Mediated Resistance in Indiana

“…), with a worldwide distribution and host range of more than 3000 plant species [1][2][3]. RKNs can cause yield losses of 15-85% in vegetables, depending on the plant species and population density [1,4]. The infective second-stage juveniles (J2s) of RKNs hatch from eggs and penetrate the roots of host plants.…”