The wild grape vines referenced grew in climates typical of the seasonal tropical forests of the Neovolcanic Axis mountains and the Sierra Madre del Sur (Gentry, 1991; Schenitzer and Bonguers, 2002). In the four municipalities studied grew in diverse climates that include semi-humid with rain from summer to winter; semi-hot humid with summer rain; moderate temperature humid with summer rain; and moderate temperature sub-humid. The wild grape vines need tree structures to develop its canopy, and they grow during wet and dry seasons, unlike the trees, which stop growing in the dry season in tropical forests (Cai et al., 2009; Sánchez-Azofeifa et al., 2009; Van der Heijden et al., 2019).
The altitude was after the precipitation in the driest period (Bio14), the second most important variable in the agroecological zoning model model (Table 1). The wild vines were located between 836 and 2300 m, and there are reports at heights up to 2300 m (Rzedowski and Calderon, 2005). However, at this altitude their presence is reduced because of the low temperature. This characteristic of adaptive vulnerability may explain why these lianas are not abundant in temperate zones. Franco-Mora et al. (2012) found that V. tiliifolia develops better in warm zones.
Wild Vitis vines have been found to thrive in different types of soils, including Humic Andosols, Eutric Regosols, Lithosols, Haplic Phaeozems, and Rendzics (Luna-Gaona et al., 2010), and grow wild in acid soil with high organic matter content (Galindo-Tovar et al., 2019). These findings coincide with characteristic soils of the sampling area in the present study, which include Acrisols, Cambisols, Luvisols, Phaeozems, Redzics, and Vertisols. In Huatusco, Cosautlán, and Ixtaczoquitlán the soils were Cambisols, Luvisols, Phaeozems, and Humic Acrisols, which are characterized by superficial horizons, high clay content, considerable organic matter, and acidity. Luvisols have high clay content in the subsoil (FAO, 1999). In the municipality of Atlahuilco the soils were Luvisols and Redzics, the latter shallow with high organic matter content, very fertile, stony, resting on igneous rock, and rich in lime (INEGI, 2018).
Tropical forests and jungle soils are rich in OM (organic matter) content. Since most of the nitrogen, phosphorus, and sulfur come from the mineralization of the OM, this high content increases vigor and foliar area (Swinchatt and Howell, 2004; Leeuwen et al., 2009) and fruit production in the vines (Galindo-Tovar et al., 2019). These areas have Humic Andosol, Eutric Regosol, Leptosol, and Haplic Phaoezem soils (INEGI, 2018).
V. tiliifolia was found in several states of Mexico: Guanajuato, Michoacán, Morelos, Estado de México, Hidalgo, Querétaro, Veracruz, Oaxaca, Tabasco, Chiapas, Guerrero, and Yucatán (Rzedowski and Calderón, 2005, 2007; Franco-Mora et al., 2007; Martínez et al., 2007; Luna-Gaona et al., 2010). Our findings add the states of San Luis Potosí and Puebla as potential areas for its cultivation (Fig. 4). These areas have environmental conditions similar to those in several central-southern states, with climates ranging from wet temperate with year-round rainfall, to sub-humid temperate with summer rainfall, to semi-warm with year-round rainfall, with variations of dry and warm humid climates. The physiographic characteristics of most of these include plateau, depression, mountains, and valleys, which correspond to the conditions cited by Rzedowski and Calderón (2005) for V. tiliifolia development.
The availability of water is an important environmental factor, since moderate water stress induces the production of phenolic compounds such as stilbenes and catechins (Vezzulli et al., 2007; Kounduras et al., 2007; Chaves et al., 2010; Dulec et al., 2011). High availability of water, however, implies low phenolic and anthocyanin content in the plant (Van Leeuwent et al., 2004). The phenolic content is affected not only by latitude but also by altitude (Taquichiri et al., 2014); the plants produce phenolic compounds as a stress response to ultraviolet exposure on the leaves and fruit (Del Castillo et al., 2014; Mayer and Higed, 2012). Low phenolic content has been observed in elevations above 3000 m (Berli et al., 2013); it was lowest in Atlahuilco, at elevations from 1750 to 2358 m. However, antioxidant content, including resveratrol, is greater at elevations between 1700 and 2000 m, because the leaves are with greater exposure to sunlight, and there are more photoprotective pigments and proline (Berli et al., 2013), resulting in greater antioxidant capacity.
The organic matter covariable was closely related to higher phenol content potential in the leaves. Organic matter in the soil influences nitrogen absorption in the plant and the formation of aromatic amino acids such as phenylalanine, tyrosine, and malonates, and some of the amino acids from which the flavonoids are derived (Stalikas, 2007; Orsat and Routray, 2017). In localities of the municipality of Ixtaczoquitlán (I-CGr, I-Tux, I-CCh), with altitudes ranging between 800 and 1000 m, and Huatusco Cerro Elotepec (H-CEI), organic matter was correlated with potential contents of the gallic acid, vanillic acid, chlorogenic acid, and vanillin in the leaves (Fig. 4). There were 29 municipalities in the state of Veracruz with high potential for growth and use of V. tiliifolia (Fig. 2). Cruz-Castillo et al. (2009) documented 21 Veracruz municipalities in which V. tiliifolia grows, and there are herbarium specimens in the Xalapa Institute of Ecology from 36 municipalities. The localities of Huatusco and Cosautlán, in the ecogeographic zone between 1000 and 2000 m, had the highest potential for phenolic content. The distribution map also shows 15 municipalities in San Luis Potosí, 17 in Hidalgo, 64 Puebla, 513 in Oaxaca, and 24 in Chiapas (Fig. 3) with significant potential for the development of V. tiliifolia with a high phenolic content in its leaves that can be used for therapeutic and nutritional purposes.