Plant iron acquisition strategy exploited by an insect herbivore

Abstract

Insect herbivores depend on their host plants to acquire macro- and micronutrients. Here we asked how a specialist herbivore and damaging maize pest, the western corn rootworm, finds and accesses plant-derived micronutrients. We show that the root-feeding larvae use complexes between iron and benzoxazinoid secondary metabolites to identify maize as a host, to forage within the maize root system, and to increase their growth. Maize plants use these same benzoxazinoids for protection against generalist herbivores and, as shown here, for iron uptake. We identify an iron transporter that allows the corn rootworm to benefit from complexes between iron and benzoxazinoids. Thus, foraging for an essential plant-derived complex between a micronutrient and a secondary metabolite shapes the interaction between maize and a specialist herbivore.

Pulcherrimin formation controls growth arrest of theBacillus subtilisbiofilm

“…In nature, the routes used for iron acquisition are highly diverse and competition between ecologically distant species is common. For instance, insect herbivores are able to hijack plant iron acquisition systems (50) and the soil bacterium Streptomyces venezuelae produces a volatile compound (trimethylamine) that enhances colonisation by the bacterium through modulating iron availability (51,52). Therefore, while there is no evidence of B. subtilis being able to use pulcherriminic acid as a siderophore, the intriguing question of how pulcherrimin is accessed and utilised in the complex soil environment remains open to multiple possibilities.…”

Root volatiles in plant–plant interactions II: Root volatiles alter root chemistry and plant–herbivore interactions of neighbouring plants

“…However, plants also release significant amounts of VOCs into the rhizosphere, which may affect plant defence and plant–herbivore interactions (Delory, Delaplace, Fauconnier, & du Jardin, ). Root chemicals, including VOCs, can affect the germination and growth of neighbouring plants (Ens, Bremner, French, & Korth, ; Jassbi, Zamanizadehnajari, & Baldwin, ) and the behaviour and performance of herbivores (Hu, Mateo, et al, ; Robert, Erb, et al, ; Robert, Veyrat, et al, ). Therefore, it is reasonable to assume that root VOCs may also affect plant–herbivore interactions of neighbouring plants.…”

Variation in root secondary metabolites is shaped by past climatic conditions

“…These metabolites defend plants against herbivores and pathogens (Mithöfer & Boland, 2012) increase abiotic stress tolerance (de Costa, Yendo, Fleck, Gosmann, & Fett-Neto, 2013; Hazarika & Rajam, 2011; Qi, Yang, Yuan, Huang, & Chen, 2015), facilitate mutualisms (Peters, Frost, & Long, 1986; Schäfer et al, 2009; Stevenson, Nicolson, & Wright, 2017), promote micronutrient uptake (Hu et al, 2018; Kobayashi & Nishizawa, 2012), or act as growth and defence regulators (Francisco et al, 2016; Kim, Ciesielski, Donohoe, Chapple, & Li, 2014; Malinovsky et al, 2017). Although secondary metabolites can have highly specialized functions, there is growing evidence that individual many of them serve multiple purposes (Hu et al, 2018; Katz et al, 2015; J. Li et al, 2018; Malinovsky et al, 2017; Møller, 2010).…”