Tracing the history of plant traits under domestication in cranberries: potential consequences on anti-herbivore defences

Abstract

The process of selecting certain desirable traits for plant breeding may compromise other potentially important traits, such as defences against pests; however, specific phenotypic changes occurring over the course of domestication are unknown for most domesticated plants. Cranberry (Vaccinium macrocarpon) offers a unique opportunity to study such changes: its domestication occurred recently, and we have access to the wild ancestors and intermediate varieties used in past crosses. In order to investigate whether breeding for increased yield and fruit quality traits may indirectly affect anti-herbivore defences, the chemical defences have been examined of five related cranberry varieties that span the history of domestication against a common folivore, the gypsy moth (Lymantria dispar). Direct defences were assessed by measuring the performance of gypsy moth caterpillars and levels of phenolic compounds in leaves, and indirect defences by assaying induced leaf volatile emissions. Our results suggest that breeding in cranberry has compromised plant defences: caterpillars performed best on the derived NJS98-23 (the highest-yielding variety) and its parent Ben Lear. Moreover, NJS98-23 showed reduced induction of volatile sesquiterpenes, and had lower concentrations of the defence-related hormone cis-jasmonic acid (JA) than ancestral varieties. However, induced direct defences were not obviously affected by breeding, as exogenous JA applications reduced caterpillar growth and increased the amounts of phenolics independent of variety. Our results suggest that compromised chemical defences in high-yielding cranberry varieties may lead to greater herbivore damage which, in turn, may require more intensive pesticide control measures. This finding should inform the direction of future breeding programmes.

Analysis of Natural and Induced Variation in Tomato Glandular Trichome Flavonoids Identifies a Gene Not Present in the Reference Genome

“…Because the genetic diversity of S. lycopersicum is relatively low (Rodriguez-Saona et al, 2011), a polymorphic mapping population was obtained by crossing JP117 to the wild species S. pennellii accession LA0716. S. pennellii LA0716 was chosen because it is sexually compatible with the cultivated tomato and there are many DNA polymorphisms characterized between the two species.…”

The Study of Herbivory and Plant Resistance in Natural and Agricultural Ecosystems

“…Wild tomato was more tolerant of defoliation than a domesticated tomato variety, possibly because of higher allocation to leaves and fruits and lower allocation to storage organs in the domesticated tomato (22). In cranberry, resistance to gypsy moth was lower on more derived, higher-yielding varieties than on wild selections (23). The reduced resistance in more derived varieties was correlated to some extent with reduced induction of sesquiterpenes and reduced levels of jasmonic acid.…”

“…Rodriguez-Saona et al (23), for example, have pointed out that the importance of induced plant volatiles in facilitating the action of natural enemies has only recently been discovered, and the plant traits important to this mechanism of plant defense have probably been altered during selection. This idea is supported by the research of Rasmann et al .…”

Crop domestication, global human-mediated migration, and the unresolved role of geography in pest control

“…Insect herbivores typically perform better on agricultural plants than on wild ancestors, due to reductions in secondary compounds during crop domestication (Harvey et al, 2007;Rodriguez-Saona et al, 2011;Dávila-Flores et al, 2013;Szczepaniec et al, 2013;Turcotte et al, 2014). Crop domestication may facilitate herbivore populations in other ways as well.…”