Edaphoclimatic Descriptors of Wild Tomato Species (Solanum Sect. Lycopersicon) and Closely Related Species (Solanum Sect. Juglandifolia and Sect. Lycopersicoides) in South America

Abstract

Wild species related to cultivated tomato are essential genetic resources in breeding programs focused on food security to face future challenges. The ecogeographic analysis allows identifying the species adaptive ranges and most relevant environmental variables explaining their patterns of actual distribution. The objective of this research was to identify the diversity, ecological descriptors, and statistical relationship of 35 edaphoclimatic variables (20 climatic, 1 geographic and 14 edaphic variables) from 4,649 accessions of 12 wild tomato species and 4 closely related species classified in Solanum sect. Lycopersicon and clustered into four phylogenetic groups, namely “Lycopersicon group” (S. pimpinellifolium, S. cheesmaniae, and S. galapagense), “Arcanum group” (S. arcanum, S. chmielewskii, and S. neorickii), “Eriopersicon group” (S. habrochaites, S. huaylasense, S. corneliomulleri, S. peruvianum, and S. chilense), “Neolycopersicon group” (S. pennellii); and two phylogenetically related groups in Solanum sect. Juglandifolia (S. juglandifolium and S. ochranthum), and section Lycopersicoides (S. lycopersicoides and S. sitiens). The relationship between the climate and edaphic variables were determined by the canonical correlation analysis, reaching 89.2% of variation with the first three canonical correlations. The most significant climatic variables were related to humidity (annual evapotranspiration, annual precipitation, and precipitation of driest month) and physicochemical soil characteristics (bulk density, pH, and base saturation percentage). In all groups, ecological descriptors and diversity patterns were consistent with previous reports. Regarding edaphoclimatic diversity, 12 climate types and 17 soil units were identified among all species. This approach has promissory applications for biodiversity conservation and uses valuable genetic resources related to a leading crop.

Distribution and Climatic Adaptation of Wild Tomato (Solanum lycopersicum L.) Populations in Mexico

“…Unlike the results obtained by Ramirez et al [ 38 ] on the climatic variables of greatest importance for the diversity and distribution of wild and related tomato species in Latin America, the variables that make up each PC are not grouped uniformly, i.e., in each component, there are variables related to temperature and humidity. Likewise, variables such as altitude and annual mean temperature, considered very relevant for the distribution of tomato species [ 38 , 39 ], were integrated in the third component. Given these results, it can be assumed that the distribution of wild tomato in Mexico is determined by the presence of thermal and pluvial factors in the same proportion, unlike the 12 wild and four related species distributed in Latin America that are more affected by precipitation [ 38 , 39 ].…”

“…Likewise, variables such as altitude and annual mean temperature, considered very relevant for the distribution of tomato species [ 38 , 39 ], were integrated in the third component. Given these results, it can be assumed that the distribution of wild tomato in Mexico is determined by the presence of thermal and pluvial factors in the same proportion, unlike the 12 wild and four related species distributed in Latin America that are more affected by precipitation [ 38 , 39 ]. These changes in the distribution associated with climatic variables can be attributed to the tomato domestication process.…”

“…Regarding climate diversity, the predominant climate type in the wild populations of Mexico is temperate (C), unlike the Latin American tomato species where dry climates predominate (B) [ 39 ]. This condition is also favorable to know the environmental suitability of each group of species.…”

“…Ecological descriptors were calculated using the methodology proposed by Steiner and Greene [ 60 ], and widely used in different species [ 28 , 38 , 39 , 61 , 62 ].…”

“…Species density maps were constructed by identifying all accessions within 1 km of each other. This distance was chosen based on previous studies of diversity in wild tomato species in South America [ 39 ] and potato species (Solanum Sect. Petota), a sister group of tomatoes [ 64 , 65 ].…”