Carotenoid rich tomato fruits due to overexpression of an endoplasmic reticulum specific sHSP isoform

ZAYAS ALDANA; RENZI DJ; SOSSI ML; ZANOR MI

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology; 2023

Tomato (Solanum lycopersicum) is the second most important vegetable crop worldwide after potato and its production is destined either for the fresh fruit market or the processed food industries. To extend the commercialization period of fresh tomato, fruits are stored at low temperatures after harvest. Previous analysis of the fruit transcriptome after cold storage (Gonzalez et al, 2019) have shown an up-regulation of the transcription of genes encoding antioxidant enzymes and low molecular weight (< 45KDa) chaperon-like proteins or small heat shock proteins (sHSPs). Plants are unique in expressing in a cell a multiplicity of cytosolic sHSPs and specific sHSPs targeted to the plastids, the endoplasmic reticulum (ER) and the mitochondria (Siddique et al. 2008). sHSPs play an important role in thermotolerance as their transcripts exhibit a dramatic up-regulation when the plant is subjected to temperatures above optimum growth values. Beside their roles in stress tolerance, they play major roles in development as some of them have been detected in special plant organs, such as maturing pollen, germinating seeds, developing embryos, and growing fruits. In this study, we have generated and characterized transgenic tomato plants overexpressing and silencing the sHsp21,5-ER gene using a fruit specific promoter. Our results suggest that sHsp21,5-ER positively influences the accumulation of the pigment -carotene in fruits even after chilling. Ripe tomato fruit color is the result of chlorophyll breakdown and carotenoid accumulation. Color is considered one of the most important quality attributes of tomato fruit for consumer acceptance and pigment composition contributes to the fruit nutritional value. Overexpression of an endoplasmic reticulum specific sHSP isoform leads to nutritional valuable fruits.