Host plant genetic control of associated fungal and insect species in a Populus hybrid cross

Abstract

Plants employ a diverse set of defense mechanisms to mediate interactions with insects and fungi. These relationships can leave lasting impacts on host plant genome structure such as rapid expansion of gene families through tandem duplication. These genomic signatures provide important clues about the complexities of plant/biotic stress interactions and evolution. We used a pseudo‐backcross hybrid family to identify quantitative trait loci (QTL) controlling associations between Populus trees and several common Populus diseases and insects. Using whole‐genome sequences from each parent, we identified candidate genes that may mediate these interactions. Candidates were partially validated using mass spectrometry to identify corresponding QTL for defensive compounds. We detected significant QTL for two interacting fungal pathogens and three insects. The QTL intervals contained candidate genes potentially involved in physical and chemical mechanisms of host–plant resistance and susceptibility. In particular, we identified adjoining QTLs for a phenolic glycoside and Phyllocolpa sawfly abundance. There was also significant enrichment of recent tandem duplications in the genomic intervals of the native parent, but not the exotic parent. Tandem gene duplication may be an important mechanism for rapid response to biotic stressors, enabling trees with long juvenile periods to reach maturity despite many coevolving biotic stressors.

Genetic underpinnings of arthropod community distributions in Populus trichocarpa

“…The previous exposure of P. trichocarpa genotypes in their native range with the same or similar species as our study can be an important driver in the genetic mechanisms underlying host recognition and resistance mechanisms. Indeed, it has been demonstrated many times in Populus that a life history of plant–biotic interactions leaves a lasting impact on plant genome structure (Haruta et al ., 2001; Major & Constabel, 2008; Simon et al ., 2020). Further supporting the importance of these evolutionary relationships, we found that the latitude in which the genotypes were originally collected was important to arthropod community observed within many of our garden surveys.…”

Editing Metabolism, Sex, and Microbiome: How Can We Help Poplar Resist Pathogens?

“…Poplar QTLs are described in the paper [254]. In P. trichocarpa, 4 QTL intervals containing a total of 38 markers are associated with a quantitative control of fungal pathogens, and another 3 QTL intervals with 40 markers are required for defense against phytophagous insects.…”