CONICET | Buscador de Institutos y Recursos Humanos

Plants have the largest number of small heat shock proteins (sHsps) among eukaryotes, but little is known about their function in vivo. They accumulate in response to different stresses, and specific sHsps are also expressed during developmental processes such as seed development, germination, and ripening. The presence of organelle-specific sHsps appears to be unique to plants. Ripening is the late developmental phase of tomato (Solanum lycopersicum L) fruit that starts when the green fruit reaches the final size and is completed when the fruit is red. This process also occurs in mature green fruits that have been harvested. Shelf life, one of the most important agronomic traits for tomato, is lengthened by storing fruit at low temperature. Susceptible fruits suffer physiological disorders known as chilling injury. It has been reported that sHsps accumulated under cold stress. The overall objective of this study was to evaluate the role of sHsps under chilling conditions in fruits from two tomato cultivars, cv Micro-Tom (tolerant to chilling stress) and Minitomato (sensitive to cold stress). Additionally, fruit from transgenic plants with altered level of a mitochondrial sHsp in these two cultivars were analysed in their phenotype, antioxidant response, gene expression and sHsp protein levels. Although transgenic and non-transformed plants were phenotypically similar under control conditions, sHsps were induced during ripening in fruit from both cultivars. However, in Micro-Tom fruit but not in Minitomato fruit sHsps were induced in response to storage at low temperature. Micro-Tom fruits silenced in mitochondrial sHsp were more susceptible to chilling injury while Minitomato overexpressing fruits were more tolerant to the cold treatment. These results substantiate the hypothesis that mitochondrial sHsp may participate in the chilling tolerance mechanism of tomato fruit.