The defensive benefit and flower number cost of selenium accumulation in Brassica juncea. Issue 5 (17th August 2019)

• Record Type: Journal Article
• Authors: Steven, Janet C; Culver, Alexander
• Editors: Orians, Colin
• Is Part Of: AoB plants. Volume 11:Issue 5(2019)
• Publication Date: 2019-08-17
• Subjects: Accumulation -- Brassica juncea -- elemental defence -- herbivory -- hyperaccumulation -- Pieris rapae -- selenium; Plants -- Periodicals; Botany -- Periodicals; 580.5
• DOI: 10.1093/aobpla/plz053
• Languages: English
• ISSNs: 2041-2851

Abstract

Abstract: Some plant species accumulate selenium in their tissues in quantities far above soil concentrations, and experiments demonstrate that selenium can serve as a defence against herbivores and pathogens. However, selenium may also cause oxidative stress and reduce growth in plants. We measured growth, selenium accumulation and herbivory in four varieties of the selenium accumulator Brassica juncea to investigate the cost of accumulation as well as its benefit in reducing herbivory. We measured selenium levels, plant size and flower number in four varieties of B. juncea watered with sodium selenate or treated as controls. We also conducted no-choice herbivory trials on leaves from both treatments with the specialist herbivore Pieris rapae . The selenate treatment slightly increased leaf number over the control, but tissue concentrations of selenium and flower number were negatively correlated in some varieties. In herbivory trials, leaves from the plants in the selenate treatment lost less leaf tissue, and the majority of larvae given leaves from selenate-treated plants ate very little leaf tissue at all. In the variety with the highest selenium accumulation, leaves from selenate-treated plants that showed reduced flower production also experienced less herbivory in feeding trials. The protective advantage of greater selenium accumulation may be offset by negative effects on reproduction, and the relatively low level of selenium accumulation in this species as compared to more extreme hyperaccumulators could reflect the minimum level necessary to enhance protection from herbivory. Abstract : Selenium is an essential element for animal health, but it can be toxic at high concentrations. Plants are known to exploit this by storing high levels of selenium in their leaves and poisoning their animal enemies. We found that brown mustard plants that absorbed selenium from the soil and accumulated it in their leaves were in fact eaten less by a moth larva. However, at high concentrations of selenium plants also made fewer flowers. Accumulating selenium protects the plants from herbivores, but it also may come at a cost in reproduction.