Glyphosate spray drift in Coffea arabica – Sensitivity of coffee plants and possible use of shikimic acid as a biomarker for glyphosate exposure Lars C. Schrübbers a,⇑ , Bernal E. Valverde a,b , Jens C. Sørensen c , Nina Cedergreen a a Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Frederiksberg C, Denmark b Investigación y Desarrollo en Agricultura Tropical S.A. (IDEA Tropical), Alajuela, Costa Rica c Department of Food Science, Faculty of Science, University of Copenhagen, Frederiksberg C, Denmark article info Article history: Received 17 June 2014 Accepted 12 August 2014 Available online 20 August 2014 Keywords: Glyphosate Coffea arabica Spray drift Dose–response curve Shikimic acid accumulation Biomarker abstract Glyphosate is widely used in coffee plantations to control weeds. Lacking selectivity, glyphosate spray drift is suspected to cause adverse effects in coffee plants. Symptoms caused by glyphosate can be similar to those produced by other stress factors. However, shikimic acid accumulation should be a useful bio- marker for glyphosate exposure as shown for other crops. The aim of this study was to assess the sensi- tivity of coffee plants towards glyphosate on different biological response variables and to evaluate the use of shikimic acid as biomarker. Dose–response experiments yielded ED 50 values (50% effect dose) in the range of 38–550 g a.e. ha 1 depending on the quantitative or qualitative variable monitored. The fre- quency of plants showing symptoms was the most sensitive variable. The best sampling time for shikimic acid accumulation was 1–2 weeks after glyphosate application, depending on experimental conditions. The highest shikimic acid accumulation was observed in young leaves. Shikimic acid is a suitable biomarker for a glyphosate exposure in coffee, using only young leaves for the analysis. Young coffee plants are susceptible to glyphosate damage. If symptoms are absent the risk of severe crop damage or yield loss is low. Ó 2014 Elsevier Inc. All rights reserved. 1. Introduction After more than 35 years of commercialization, [1] glyphosate (the active substance in Roundup Ò ) is the dominant herbicide worldwide. It is characterized as non-selective with a broad weed spectrum, featuring a unique mode of action. Once taken up, gly- phosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) which leads to, besides visible symptoms, an accumulation of shikimic acid in plant tissue [2]. The accumulation of shikimic acid can be used as a biomarker for a previous glyphos- ate exposure in susceptible plants [3–7]. Determining the concen- tration of shikimic acid rather than glyphosate itself has two advantages; glyphosate is challenging to analyze [6] and an accumulation of shikimic acid is a proof of an internal glyphosate concentration high enough to cause a biological response at a physiological level. Glyphosate mainly affects young, growing plant tissue. This characteristic is due to its translocation from source to sink tissue and the presence of EPSPS primarily in the active meristems [8]. Glyphosate is commonly used in coffee plantations to control weeds that compete with the crop for resources and reduce coffee yield [9]. Coffee, being one of the most popular beverages in the world, has a significant production volume and economic impor- tance. In 2011/12 approximately 8 million tons of coffee were pro- duced globally with an estimated export value of US$ 21.6 billion [10]. Solely in Mexico and Central America about four million peo- ple are directly economically dependent on the crop, raising to more than double when all aspects of coffee production, sales and distribution are considered [11]. Because of the lack of glyphosate selectivity, there is a risk of crop injury through unintended crop exposure from spray drift. It is assumed that up to 10% of the applied herbicide can reach non-target crop plants in the form of spray drift [12–14], but the proportion could be higher [15,16]. Adverse effects after coffee exposure to glyphosate have been shown both as damage [17,18], and as a reduction in plant nutrient concentration [19] after a glyphosate spray drift simulation. The cause of the reduced http://dx.doi.org/10.1016/j.pestbp.2014.08.003 0048-3575/Ó 2014 Elsevier Inc. All rights reserved. ⇑ Corresponding author. Address: Environmental Chemistry and Physics, Depart- ment of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg C, Denmark. E-mail address: schruebbers@plen.ku.dk (L.C. Schrübbers). Pesticide Biochemistry and Physiology 115 (2014) 15–22 Contents lists available at ScienceDirect Pesticide Biochemistry and Physiology journal homepage: www.elsevier.com/locate/pest