Journal Article

Selenium accumulation protects plants from herbivory by Orthoptera via toxicity and deterrence

Marcus, Matthew A, Fakra, Sirine, Lindblom, Stormy Dawn, Pilon-Smits, Elizabeth A.H, Quinn, Colin F, Freeman, John L

2007

Overview

To investigate whether selenium (Se) accumulation in plants provides a chemical defense against generalist insect herbivores, the feeding preference and performance of a mix of orthopteran species were investigated. The selenium hyperaccumulator Stanleya pinnata and accumulator Brassica juncea were used in herbivory studies in the laboratory, and S. pinnata was also used in a manipulative field experiment. In laboratory studies, both crickets and grasshoppers avoided plants pretreated with selenate, while those given no choice died after eating leaves with elevated Se (447 ± 68 and 230 ± 68 μg Se g⁻¹ DW, respectively). B. juncea has previously been shown to accumulate selenate, while S. pinnata hyperaccumulates methyl-selenocysteine. Thus, these findings demonstrate that both inorganic and organic forms of selenium protect plants from herbivory. Grasshoppers fed S. pinnata contained methylselenocysteine in their midgut and absorbed this form into surrounding tissues. In a manipulative field experiment, methylselenocysteine protected S. pinnata from invertebrate herbivory and increased its long-term survival rate over an entire growth season. In native habitats of selenium hyperaccumulators, orthopterans represent a major group of insect herbivores. Protection offered by organic selenium accumulation against these herbivores may have promoted the evolution of selenium hyperaccumulation in plants.

• Publisher: Oxford, UK : Blackwell Publishing Ltd,Blackwell Science,Blackwell Publishing Ltd
• Subject: analogs & derivatives / Animals / Astragalus Plant / Astragalus Plant - metabolism / Brassica juncea / Brassicaceae / Brassicaceae - metabolism / Cysteine / Cysteine - analogs & derivatives / Cysteine - metabolism / Cysteine - toxicity / deterrence / drug effects / Ecosystem / elemental defense / evolution / field experimentation / Grasshoppers / Gryllidae / habitats / Herbivores / herbivory protection / Hyperaccumulators / ingestion / Insect pests / invertebrates / Leaves / metabolism / methylselenocysteine / Midgut / Organoselenium Compounds / Organoselenium Compounds - metabolism / Organoselenium Compounds - toxicity / Orthoptera / Orthoptera - drug effects / Phytophagous insects / Phytoremediation / Plant Leaves / Plants / selenates / Selenium / selenium (Se) hyperaccumulator / Selenium - metabolism / Selenium - toxicity / Selenocysteine / Selenocysteine - analogs & derivatives / Stanleya / Stanleya pinnata / survival rate / toxicity