High-Altitude Wild Species Solanum arcanum LA385—A Potential Source for Improvement of Plant Growth and Photosynthetic Performance at Suboptimal Temperatures

Plant growth, development, and yield of current tomato cultivars are directly affected by low temperatures. Although wild tomato species have been suggested as a potential source for low temperature tolerance, very little is known about their behavior during the reproductive phase. Here, we investigated the impact of suboptimal temperatures (SOT, 16/14°C), as compared to control temperatures (CT, 22/20°C), on plant growth, photosynthetic capacity, and carbohydrate metabolism. Under these conditions, two genotypes were analyzed: a Solanum lycopersicum cultivar Moneymaker and a high-altitude wild species Solanum arcanum LA385, from flowering onset until a later stage of fruit development. Total dry matter production in cv. Moneymaker was reduced up to 30% at SOT, whereas it was hardly affected in wild accession LA385. Specific leaf area, total leaf area, and number of fruits were also decreased at SOT in cv. Moneymaker. In contrast, wild accession LA385 showed an acclimation to SOT, in which Φ_PSII and net CO₂ assimilation rates were less affected; a similar specific leaf area; higher total leaf area; and higher number of fruits compared to those at CT. In addition, LA385 appeared to have a more distinct sucrose metabolism than cv. Moneymaker at both temperatures, in which it had higher contents of sucrose-6-phosphate, sucrose, and ratio of sucrose: starch in leaves and higher ratio of sucrose: hexose in fruits. Overall, our findings indicate that wild accession LA385 is able to acclimate well to SOT during the reproductive phase, whereas growth and development of cv. Moneymaker is reduced at SOT.