Crw1 - A Novel Maize Mutant Highly Susceptible to Foliar Damage by the Western Corn Rootworm Beetle

Bala Puchakayala Venkata,Stephen Moose,Clint Chapple,Nick Lauter,Gurmukh Johal,Xu Li,Christian Krupke

doi:10.1371/journal.pone.0071296

Abstract

Western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae), is the most destructive insect pest of corn (Zea mays L.) in the United States. The adult WCR beetles derive their nourishment from multiple sources including corn pollen and silks as well as the pollen of alternate hosts. Conversely, the corn foliage is largely neglected as a food source by WCR beetles, leading to a perception of a passive interaction between the two. We report here a novel recessive mutation of corn that was identified and named after its foliar susceptibility to corn rootworm beetles (crw1). The crw1 mutant under field conditions was exceptionally susceptible to foliar damage by WCR beetles in an age-specific manner. It exhibits pleiotropic defects on cell wall biochemistry, morphology of leaf epidermal cells and lower structural integrity via differential accumulation of cell wall bound phenolic acids. These findings indicate that crw1 is perturbed in a pathway that was not previously ascribed to WCR susceptibility, as well as implying the presence of an active mechanism(s) deterring WCR beetles from devouring corn foliage. The discovery and characterization of this mutant provides a unique opportunity for genetic analysis of interactions between maize and adult WCR beetles and identify new strategies to control the spread and invasion of this destructive pest.

Highlights

Corn rootworms are among the most serious insect pests of corn in the United States (U.S.) and have recently been introduced to the European Union (E.U.) as well [1]
The number of beetles increased over time on these selected plants which led to their substantial defoliation
These results clearly indicated that genetic mutations led to exceptional foliar herbivory by the Western corn rootworm (WCR) beetles

Summary

Introduction

Corn rootworms are among the most serious insect pests of corn in the United States (U.S.) and have recently been introduced to the European Union (E.U.) as well [1]. The larval stage which feeds on roots of corn and a few other grass species is significantly more damaging than the adult beetle [5,6,7]. None of the transgenic events currently registered for WCR control expose larvae to toxin levels considered to be a high dose, leading to concerns about resistance development [16]. These concerns have been further elevated by recent laboratory and field demonstrations of rapid response to selection in the absence of mating with unexposed beetles [17,18]. Corn germplasm with robust resistance to WCR has not yet been identified [1,19]

Methods

Results

Conclusion