Abstract
Genomic loci related with resistance to gall-inducing insects have not been identified in any plants. Here, association mapping was used to identify molecular markers for resistance to the gall wasp Leptocybe invasa in two Eucalyptus species. A total of 86 simple sequence repeats (SSR) markers were screened out from 839 SSRs and used for association mapping in E. grandis. By applying the mixed linear model, seven markers were identified to be associated significantly (P ≤ 0.05) with the gall wasp resistance in E. grandis, including two validated with a correction of permutation test (P ≤ 0.008). The proportion of the variance in resistance explained by a significant marker ranged from 3.3% to 37.8%. Four out of the seven significant associations in E. grandis were verified and also validated (P ≤ 0.073 in a permutation test) in E. tereticornis, with the variation explained ranging from 24.3% to 48.5%. Favourable alleles with positive effect were also mined from the significant markers in both species. These results provide insight into the genetic control of gall wasp resistance in plants and have great potential for marker-assisted selection for resistance to L. invasa in the important tree genus Eucalyptus.
Highlights
There are approximately 132,930 insect species around the world that can infect plant tissues and induce tumor-like gall formation[1]
The wealth of molecular markers developed in many plant species has enabled the genetic dissection of phenotypic traits using DNA based approaches, including quantitative trait locus (QTL) mapping, association mapping (AM) and genomic selection[17]
AM has been proposed as a powerful method for fine mapping because it can take full advantage of linkage disequilibrium (LD) and historical recombinations in natural populations to identify molecular markers located within the extent of LD decay of a causal or functional genetic variant[19,21,22]
Summary
There are approximately 132,930 insect species around the world that can infect plant tissues and induce tumor-like gall formation[1]. Eucalyptus trees (eucalypts) have been cultivated worldwide for timber, fuel, pulp and paper purposes, with global plantations totaling at more than 21 million ha[8] In their native range, eucalypts sustain a rich fauna of gall-inducing insects[9] and are specific hosts to several gall wasps in the family Eulophidae (Hymenoptera: Chalcidoidea), including Leptocybe invasa Fisher & La Salle (Fig. 1) which typically induces bump-shaped galls on the leaf midribs, petioles and stems of young susceptible trees[10]. Genomic selection applies breeding populations to scan genome-scale molecular data for optimal phenotypes and holds great promise for plant breeding efforts[20] Both QTL mapping and genomic selection have relatively low resolution with the causative genetic variant, and marker-gene linkage can be lost through recombination in other populations or advanced generations, limiting their applications in breeding and gene function studies[17]. Genomic loci related with galler insect resistance have not yet been reported in any plants, and the genetic mechanism underlying such a resistance remains to be clarified
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
