Evaluation of temperature stress tolerance in cultivated and wild tomatoes using photosynthesis and chlorophyll fluorescence

Abstract

Tomato cultivation at lower or higher temperatures than the optimum negatively affects plant growth and development. Large differences in abiotic stress tolerance have been found between Solanum lycopersicum and wild tomato species. Our aim was to compare temperature stress tolerance in cultivated and wild tomato genotypes to identify cold- and heat-tolerant tomatoes for further utilization in tomato breeding. The maintained net photosynthetic rate (PN) and chlorophyll fluorescence was related to the tolerance of tomatoes at temperature stress. The PN and chlorophyll fluorescence of one cultivated tomato (Ly from S. lycopersicum) and six wild tomatoes genotypes (Ha from Solanum habrochaites, Pe from Solanum pennellii, Pi1 and Pi2 from Solanum pimpinellifolium, Pr1 and Pr2 from Solanum peruvianum) grown at low (12 °C) and high (33 °C) temperatures were compared. The PN of four tomato genotypes during temperature stress were lower than the control, but not in Pe, Pr1, and Pr2. The maximum quantum efficiency of photosystem II (Fv/Fm) of the cultivated tomatoes was lower at both 12 and 33 °C than the control using Handy PEA, whereas Fv/Fm using MINI-PAM was lower only at 12 °C. The chlorophyll fluorescence OJIP transient (OJIP curve) revealed differences between temperature stress responses and tomato genotype. With the exception of Pr2, the Fv/Fm in wild tomatoes was unaffected by temperature stress; however, they still maintained clear genotype differences for other physiological traits such as PN, quantum yield of PSII (Fq′/Fm′), electron transport rate, non-photochemical quenching, and the fraction of open PSII centers (qL). These results indicated that the wild tomato varieties Pe and Pr1 had the highest temperature stress tolerance, while the cultivated species was the more sensitive to temperature stress in comparison. In general, the wild tomato genotypes were more tolerant to both cold and heat stress than the cultivated tomato, suggesting that these wild species could be used to uncover underlying mechanisms of temperature stress tolerance and will be promising sources of genetic variability for temperature stress tolerance in breeding programs.