Exploring the potential for genetic breeding of Amblyseius swirskii Athias-Henriot adapted to tomato plants
Paper ID : 1067-IPCA4 (R1)
Mehdi Bohloolzadeh *1, Diego Serrano-Carnero1, Efren Millet1, Saioa Legarrea2, Marta Montserrat1
1Institute for Mediterranean and Subtropical Horticulture “La Mayora”, Spanish National Research Council–University of Malaga (IHSM-UMA-CSIC)
2Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands
Exploring intraspecific genetic variability and heritability of relevant traits for biological pest control is a prerequisite to reveal the potential for genetic breeding of biological control agents under unfavorable conditions. Tomato is considered a hostile crop for the predatory mite Amblyseius swirskii because its constitutive defenses, i.e. glandular trichomes (GT, hereafter), entrap individuals and impede their foraging. In the present study, we investigated the potential for genetic breeding of Amblyseius swirskii’s performance on tomato plants. We used twenty isofemale lines created from a wild population to evaluate the genetic variability and heritability of the trait “tolerance to tomato trichomes (TTT)”, by measuring the ability of individuals (females) to walk through tomato plants and reach a patch with food. We estimated TTT on four tomato genotypes expressing different trichome densities and types: Ailsa Craig (wild genotype with all types of trichomes), woolly (with an excess of type I GT), lapageria (with mostly type VI GT), and hairless (with distorted trichomes). The experiment was a full-nested design including 20 females tested per tomato genotype and isofemale line; thus, a total of 1600 individuals were tested, 400 per plant genotype. We recorded the distance walked by females through the stems during a 30 minutes period, the fraction of individuals that were entrapped by different types of trichomes, and the fraction of individuals successfully reaching the patch with food. Statistical analyses were done using the computer environment R, dependent variables were analyzed using generalized linear mixed model (GLMM, glmm package), and TTT heritability was estimated using GLMM implemented through the MCMCglmm package in a Bayesian framework using Markov chain Monte Carlo (MCMC) sampling. Results revealed significant differences in the three dependent variables among plant genotypes and a significant TTT variability among isofemale lines and heritability, only on the mutant lapageria. The lack of heritability on the other genotypes was caused by a too high (wild type), too low (hairless), and too artificial (woolly), selection pressure. We conclude that the plant trait hampering the establishment of A. swirskii on tomato plants is the presence of Type VI GT. Results indicate that genetic selection of strains performing better in the presence of type VI GT is possible. Artificial selection to create a strain tolerant to tomato type VI trichomes is currently being run at the IHSM La Mayora. Succeeding will improve the capability of A. swirskii to overcome entrapment by trichomes in commercial tomato genotypes.
genetic breeding, genetic variability, heritability, predatory mites, tomato genotypes, glandular trichomes
Status : Abstract Accepted (Oral Presentation)