Evaluation of Freezing Tolerance in Solanum sitiens I.M. Johnst. Introgression Lines

Abstract

Tomato (Solanum lycopersicum L.) is susceptible to thermal stress, both at low and high temperatures, which negatively impacts growth, reproduction, and y ield. To improve tolerance to abiotic stresses, breeding programs often incorporate traits from wild relatives. In this context, Solanum sitiens is considered a potential source of freezing tolerance. This study evaluated freezing tolerance in S. sitiens introgression lines (SILs). Preliminary experiments compared the response of S. sitiens with the tomato commercial accession LA4354. Young plants of both genotypes were exposed to 0, –2, and –4 °C for 4 and 6 hours. S. sitiens survived all treatments, showing a consistent level of tolerance. Subsequently, 26 genotypes were evaluated: 24 SILs, S. sitiens as tolerant control, and LA4354 as a susceptible control. Four replicates per genotype were used. Experimental units consisted of 5-week-old SIL and LA4354 plants, and 7-week-old S. sitiens plants. The trial was conducted using an incomplete block design with two treatments: –2 °C for 6 hours and –4 °C for 6 hours. A scoring scale was developed to assess tolerance within the study population, and data were analyzed using a linear model. The overall analysis detected significant differences among genotypes, with SIL LA5287 exhibiting the highest tolerance at –2 °C. However, pairwise comparisons adjusted with the Benjamini–Hochberg procedure did not reveal statistically significant differences.