Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Resin exudation profile, chemical composition, and secretory canal characterization in contrasting yield phenotypes of Pinus elliottii Engelm Franciele A. Neis, Fernanda de Costa, Márcia Rodrigues de Almeida, Luana Caroline Colling, Camila Fernanda de Oliveira Junkes, Janette Palma Fett, Arthur G. Fett-Neto ⁎ Center for Biotechnology and Department of Botany, Federal University of Rio Grande do Sul (UFRGS), C.P. 15005, CEP 91501-970, Porto Alegre, RS, Brazil ARTICLE INFO Keywords: Pinus resin canals tapping resin composition high yield microCT ABSTRACT In conifer stems, secretory canals synthesize and store resin for defense against herbivores and pathogens. Resin terpenes are used as raw material by an array of industrial sectors. Most forest stands operationally used in resin extraction are derived from seeds, showing high genetic variation, which reflects in yield. The objective of this study was to identify adult slash pine (Pinus elliottii Engelm.) trees of high yield of resin in a short timeframe by resin mass flow rate analysis, aiming at the establishment of elite forests for tapping prior to its start. In addition, the anatomical basis of resin yield was investigated by examining the correlation between parameters such as number, shape, area and internal volume of wood canals with resin production. Monoterpene composition in resin of high and low yielding trees was also compared. The resin flow-based selection method was reliable for resin yield phenotype detection, confirming this property in trees formerly identified as being of high and low resin production by conventional tapping. The reverse test for identification of high and low yield resin features in previously untapped younger plants was in good agreement with their yields after subsequent standard tapping procedure. To evaluate and quantify the three-dimensional structure of resin canals, we used microCT scans. High yielding trees had more axial resin canals when compared with low yielding ones. Frequency of putative anastomosed canals and canal diameter were also superior in the former. Chemical analyses of resin monoterpenes revealed that the ratio of α-pinene/ β-pinene was lower in more productive trees, which also had more limonene in total terpenes compared with their low yield counterparts. Data support the use of short-term resin mass flow rate analysis as a tool to identify and select high yield trees for the establishment of elite slash pine forests for resin tapping operations. Strong correlation of the superesinous phenotype with canal density and structure was also evident. 1. Introduction Conifers have developed a series of adaptive strategies to deal with herbivore and pathogen attacks (Franceschi et al., 2005; Keeling and Bohlmann, 2006; Geisler and Jensen, 2016). Resin is considered the major defense of conifers, and its composition consists of various ter- penoids such as monoterpenes, sesquiterpenes, and diterpenes (Phillips and Croteau, 1999; Martin et al., 2002; Zulak and Bohlmann, 2010). Resin is synthesized and accumulated in specialized secretory structures (isolated resin cells, multicellular resin blisters and net- worked resin canals), which may appear as a normal feature of devel- opment in tissues (constitutive defense) or may result by the induction of external factors (Bannan, 1936; Lewinsohn et al., 1994; Wu and Hu, 1997; Hudgins et al., 2003; Langenheim, 2003). A commonly induced response to mechanical damage, insect attack, fungal invasion, application of hormones and chemical stimulants is the production of traumatic resin canals in the xylem (Lombardero et al., 2000; Nagy et al., 2000; Franceschi et al., 2002; Arbellay et al., 2014). The for- mation of traumatic resin canals represents an important induced de- fense that enhances resin production and flow in response to environ- mental perturbations in tissues close to the wounded zone (Franceschi et al., 2005; DeRose et al., 2017). Resin canals of Pinaceae are differentiated into radial canals and axial canals, depending on their orientation, creating a complex net- work (Bannan, 1936; Lewinsohn et al., 1991; Rodríguez-García et al., 2014). Resin flow can be influenced by an array of factors such as ir- radiance, temperature, season, and edaphic conditions, as well as by genetics, age, and wounding (Peñuelas and Llusià, 1999; Ayres and Lombardero, 2000; Knebel et al., 2008; Rodrigues and Fett-Neto, 2009; Hood and Sala, 2015; Neis et al., 2018). Selection of high resin yield https://doi.org/10.1016/j.indcrop.2019.02.013 Received 24 August 2018; Received in revised form 27 December 2018; Accepted 7 February 2019 ⁎ Corresponding author. E-mail address: fettneto@cbiot.ufrgs.br (A.G. Fett-Neto). Industrial Crops & Products 132 (2019) 76–83 0926-6690/ © 2019 Elsevier B.V. All rights reserved. T