Contents lists available at ScienceDirect Industrial Crops & Products journal homepage: www.elsevier.com/locate/indcrop Resinosis of young slash pine (Pinus elliottii Engelm.) as a tool for resin stimulant paste development and high yield individual selection Camila Fernanda de Oliveira Junkes, João Vitor Vigne Duz, Magnus Riffel Kerber, Júlia Wieczorek, Juliana Lunelli Galvan, Janette Palma Fett, Arthur Germano Fett-Neto ⁎ Center for Biotechnology and Department of Botany, Federal University of Rio Grande do Sul, Porto Alegre, P.O. Box 15005, 91501-970, Brazil ARTICLE INFO Keywords: Resinosis Adjuvant paste Pinus elliottii Young plants ABSTRACT Pine resin, a natural source of industrially relevant terpenes, is a major non-wood forestry commodity. Resin is obtained by wounding the bark of adult trees and applying stimulant pastes with different adjuvants on the wound. Identifying new adjuvants and high resin producing trees in adult forests often requires long time and intense labor. Microtapping, i.e. use of young plants of Pinus elliottii var. elliottii cultivated in greenhouse to extract resin, was evaluated as an alternative to carry out these activities. Compounds with known effect in adult plants (ethrel, benzoic acid and potassium sulfate) and molecules involved in the transduction of defense signals (methyl jasmonate, salicylic acid, linolenic acid and isoleucine) were evaluated in young plants. One, two and three-year-old plants consistently increased resinosis when treated with potent adjuvants, mainly methyl jas- monate. The more lignified basal stems produced more resin than apical ones in the 1-year-old plants. Resin yield increased after the second year. All plants were responsive to successive stimuli, just as adult plants. High resin-yield individuals were identified by microtapping, and this phenotype was further supported by terpene- related gene expression studies associated with resinosis. Therefore, microtapping can be used for early, rapid, and simple identification of adjuvants with high resin induction capacity and of putative elite individuals for field evaluation, breeding, and clonal propagation. 1. Introduction Conifers are the most advanced group of gymnosperms that also include some of the longest living species on the planet, with individual trees often exceeding several hundred years (Warren et al., 2015). The adaptive success and co-existence with changing environmental con- ditions, competing plants, potential pests and foraging animals was only possible due to the acquisition of anatomical and chemical defense systems. These systems include sophisticated constitutive and inducible mechanisms, that involve structural, morphological or physical barriers in all major organs and different tissues (Pascual et al., 2015; Pham et al., 2014; Warren et al., 2015). Resin is a viscous fluid exuded from ducts when the tree is under herbivore or pathogen attack (Lange, 2015). The constitutive and induced resin are considered the major chemical defense of conifers, and their composition is a complex, dy- namic and variable mixture of terpenoids such as monoterpenes, ses- quiterpenes, and diterpenes (Bohlmann and Keeling, 2008; Franceschi et al., 2005; Philipps and Croteau, 1999; Zulak and Bohlmann, 2010). Pine resin is the raw material for several industrial products and one of the most important non-timber forest products (Neis et al., 2019a,b). The total annual production reaches about 1.2 million tons worldwide, supporting a wide range of multi-billion-dollar industrial applications (Yadav et al., 2015). Because it is an easy to obtain, inexpensive and renewable source material, pine resin and its products are used in the production of fungicides, insecticides, fragrances, paints and solvents, adhesives, rubber, biofuels, and especially in fine chemicals such as biodegradable polymers, precursors of drug synthesis and food ad- ditives (Neis et al., 2019b; Yadav et al., 2015). Brazil is one of the world leaders in pine resin production, mostly based on slash pine (Pinus elliottii var. elliottii) plantations of the Southeast and South regions (ARESB, 2018). Under normal growing conditions, pines accumulate between 1 and 5% of their stem mass as resin, but after treatment with chemical elicitors of resinosis the stem oleoresin content generally increases significantly (Rodrigues-Corrêa and Fett-Neto, 2012; Westbrook et al., 2013). The exudate resin is collected from a transverse wound mechanically imposed to the bark of the adult tree (bark stripping), followed by application of adjuvant paste on the damage upper line, to promote the biosynthesis and flow of https://doi.org/10.1016/j.indcrop.2019.04.048 Received 21 February 2019; Received in revised form 22 April 2019; Accepted 23 April 2019 ⁎ Corresponding author. E-mail address: fettneto@cbiot.ufrgs.br (A.G. Fett-Neto). Industrial Crops & Products 135 (2019) 179–187 0926-6690/ © 2019 Elsevier B.V. All rights reserved. T