Contents lists available at ScienceDirect Scientia Horticulturae journal homepage: www.elsevier.com/locate/scihorti Dormancy release, germination and ex situ conservation of the southern highland papaya (Vasconcellea quercifolia, Caricaceae), a wild crop relative María Manuela Urtasun a,b, *, Eugenia Mabel Giamminola a , Carol Caudle Baskin c,d , Marta Leonor de Viana a , Marcelo Nahuel Morandini a , Carola Yanina Lamas a,b , Macarena Fernanda Rojas a a Germplasm Bank of Native Species (BGEN) of the Institute of Ecology and Human Ambient (INEAH), National University of Salta, Salta, 4400, Argentina b National Council of Scientific and Technical Research (CONICET), Argentina c Department of Biology, University of Kentucky, Lexington, KY, 40506-0225, USA d Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, 40546-0321, USA ARTICLE INFO Keywords: Non-deep physiological dormancy Desiccation tolerance After-ripening Dry storage Carica papaya ABSTRACT The genetic traits of wild species closely related to crop plants provide opportunities for increased crop pro- duction and food security in the face of global climate change. Highland papayas, Vasconcellea spp., have va- luable traits for the improvement of common papaya. Vasconcellea quercifolia is the only species of the genus that inhabits both the Andean lowlands and highlands, and it has been proposed as the best option for intergenic hybrids. However, limited information is available on seed dormancy release, germination and ex situ con- servation of species belonging to this genus. We investigated the effects of desiccation and storage, in combi- nation with seven pre-germination treatments, on dormancy release and viability of seeds from five wild po- pulations of V. quercifolia along a latitudinal gradient in NW Argentina. Effectiveness of pre-germination treatments on dormancy release increased concomitantly with a decrease in seed moisture content (MC). Ultra- dry (< 3 % MC) in combination with potassium nitrate treatment, as well as dry (3–5 % MC) storage at 25 °C consistently alleviated seed dormancy. In general, desiccation and dry storage for 6 months at different tem- peratures did not affect seed viability; however, there were population differences in the ability of seeds to remain viable. Our data demonstrate the central role of seed MC in the alleviation of V. quercifolia seed dor- mancy and provide new insights into the conditions required for short- to medium-term ex situ conservation. 1. Introduction Ex situ conservation of wild plants closely related to crop species has become an increasingly important regional and global priority in the context of climate change (Fielder et al., 2016; Jarvis et al., 2015; Khoury et al., 2015; Rubio Teso et al., 2018; van Treuren et al., 2017; Vincent et al., 2013). Crop wild relatives have a wide range of genetic traits that can be used to improve crops, i.e. flavor and nutrition, re- sistance to pests and diseases and drought, heat and cold tolerance. The use of wild relatives has long been a part of crop improvement pro- grammes, and its continued use will help ensure global food security and adapt farming systems to future climate conditions (Fielder et al., 2016; Hajjar and Hodgkin, 2007; Jarvis et al., 2008; Vincent et al., 2013). Therefore, to conserve and propagate wild crop relatives, some key information is needed, particularly the seed dormancy-breaking requirements, storage behavior and variability among populations. Vasconcellea species, often known as “highland papayas” or “mountain papayas”, are widely distributed in tropical America, from Mexico to Argentina. They grow at elevations up to 4250 m above sea level (m a.s.l). This is the largest genus in the Caricaceae, and it has 21 species, five of which are included in a risk category (IUCN, 2019). Highland papayas are wild relatives of the common papaya (Carica papaya L.), and are therefore a source of genes for papaya improvement, such as tolerance to Ringspot Papaya Virus (RSPV-P) and low tem- peratures, as well as some traits related to sugar content (Coppens d’Eeckenbrugge et al., 2014). Additionally, mountain papayas secrete latex that contains high levels of proteases useful in several industries (Scheldeman et al., 2007; Torres et al., 2012), and their edible fruits have appealing organoleptic properties (e.g. aroma, taste, color) (Coppens d’Eeckenbrugge et al., 2014). Vasconcellea quercifolia A. St.- Hil. is the southernmost species of the genus and is one of the few that inhabits high altitudes, as well as lowlands (Scheldeman et al., 2007). It https://doi.org/10.1016/j.scienta.2019.109134 Received 13 August 2019; Received in revised form 5 December 2019; Accepted 12 December 2019 ⁎ Corresponding author at: Av. Bolivia 5150, 4400, Salta, Argentina. E-mail address: mmurtasun@gmail.com (M.M. Urtasun). Scientia Horticulturae 263 (2020) 109134 0304-4238/ © 2019 Elsevier B.V. All rights reserved. T