Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding

Abstract

Parasitic plants acquire diverse secondary metabolites from their hosts, including defense compounds that target insect herbivores. However, the ecological implications of this phenomenon, including the potential enhancement of parasite defenses, remain largely unexplored. We studied the translocation of glucosinolates from the brassicaceous host plant Arabidopsis (Arabidopsis thaliana) into parasitic dodder vines (Convolvulaceae; Cuscuta gronovii) and its effects on the parasite itself and on dodder-aphid interactions. Aliphatic and indole glucosinolates reached concentrations in parasite tissues higher than those observed in corresponding host tissues. Dodder growth was enhanced on cyp79B2 cyp79B3 hosts (without indole glucosinolates) but inhibited on atr1D hosts (with elevated indole glucosinolates) relative to wild-type hosts, which responded to parasitism with localized elevation of indole and aliphatic glucosinolates. These findings implicate indole glucosinolates in defense against parasitic plants. Rates of settling and survival on dodder vines by pea aphids (Acyrthosiphon pisum) were reduced significantly when dodder parasitized glucosinolate-producing hosts (wild type and atr1D) compared with glucosinolate-free hosts (cyp79B2 cyp79B3 myb28 myb29). However, settling and survival of green peach aphids (Myzus persicae) were not affected. M. persicae population growth was actually reduced on dodder parasitizing glucosinolate-free hosts compared with wild-type or atr1D hosts, even though stems of the former contain less glucosinolates and more amino acids. Strikingly, this effect was reversed when the aphids fed directly upon Arabidopsis, which indicates an interactive effect of parasite and host genotype on M. persicae that stems from host effects on dodder. Thus, our findings indicate that glucosinolates may have both direct and indirect effects on dodder-feeding herbivores.Parasitic plants make their living by extracting resources from other plants and, therefore, share many of the same ecological challenges faced by other plantfeeding organisms, including the need to acquire appropriate hosts and overcome host defenses (Runyon et al

Plants are Not Sitting Ducks: Teaching Module on Plant Biochemical Interactions with Insects

“…Glucosinolates include some of the very first secondary metabolites (i.e., compounds that do not function in plant growth and reproduction) known to deter generalist herbivores and to stimulate specialist herbivores (Vershaffelt, 1910; Fraenkel, 1959), and they continue to feature prominently in modern plant biology and entomology (e.g., Wheat et al, 2007; Clay et al, 2009). The development of Arabidopsis mutants that are altered in glucosinolate production has presented exciting opportunities to test the importance of these compounds in planta for purposes of science (e.g., Müller et al, 2010; Rohr et al, 2012; Schramm et al, 2012; Smith et al, 2016) and, we suggest, for the purpose of education.…”

Allelopathic tolerance of alfalfa (Medicago sativa L.) varieties to dodder (Cuscuta epithymum L.)

“…This relationship could be due to allelochemicals (terpenes, long-chain fatty acids, phenols, phenolic acids and lactone) that are present in the parasitic weed species C. campestris (Khanh et al, 2008, Smith et al, 2016.…”

Impact of Mutations in Arabidopsis thaliana Metabolic Pathways on Polerovirus Accumulation, Aphid Performance, and Feeding Behavior

“…It was previously reported that the genetic suppression of MYC function in the myc234 mutant increases aphid attraction by releasing different volatiles and potentially also by modifying composition of plant metabolites [54]. In the quad mutant, the synthesis of both indole and aliphatic glucosinolates is impaired, but no impact on M. persicae population growth was reported [49,55]. Although M. persicae should not be in contact with vacuolar glucosinolates-hydrolyzing myrosinases when ingesting sap, indole glucosinolates are nonetheless degraded in the aphids and this degradation may be responsible for the deterrent effect of these compounds on aphids [14].…”