Leaf nutrient relationships to gall induced hypersensitive reactions in 'Terminalia glabrescens'

• Published in: Plant protection quarterly Vol. 29; no. 1; pp. 11 - 15
• Main Authors: Magalhães, Henrique, Fernandes, G Wilson, Barbosa, Milton
• Format: Journal Article
• Language: English
• Published: Orange East Polymeria Publishing 01.01.2014
• Subjects: Gall wasps; Nutrition; Plant-pathogen relationships; Plants; Brazil
• ISSN: 0815-2195

Hypersensitive reaction (HR) has been recognised as an important mechanism by which plants defend against many sessile herbivores, including galling insects. HR results from a series of morphological, biochemical and physiological processes leading to the localisation, confinement and death of the attacked tissue and intruders. We hypothesised that leaf nutrient concentrations are related to the incidence of HR induced by a gall midge (Diptera, Cecidomyiidae) on Terminalia glabrescens Mar t. (Combretaceae). We compared macro and micronutrient concentrations between leaves presenting HR and "healthy" leaves, and related the HR area to the concentrations of the different nutrients. The Ca concentration was positively associated with the HR area while K concentration was negatively related to it, which may be explained by the influx of Ca2+ and efflux of K+ at the triggering of HR. There was an inverse relationship between HR and the concentrations of the nutrients Mn, Cu and Fe, most likely due to the HR detoxification function played by these metals, which can prevent cell death and turn the HR into a symptomless undetectable reaction. These results suggest that leaf nutrient concentrations are related to HR incidence.