Physiological response to heat stress of tomato ‘Micro-Tom’ plants expressing high and low levels of mitochondrial sHSP23.6 protein

• Published in: Plant growth regulation 2013-06, Vol.70 (2), p.175-185
• Main Authors: Huther, Cristina Moll, Ramm, Aline, Rombaldi, Cesar Valmor, Bacarin, Marcos Antonio
• Format: Article
• Language: English
• Subjects: Agriculture; Biomedical and Life Sciences; Life Sciences; Original Paper; Plant Anatomy/Development; Plant Physiology; Plant Sciences
• ISSN: 0167-6903; 1573-5087
• DOI: 10.1007/s10725-013-9790-y

Tomato ‘ Micro-Tom’ plants were transformed for high or low expression of the mitochondrial small “heat shock” protein (HSP) (MT-sHSP23.6) to evaluate their response to high temperature. The plants were raised for 59 days under a controlled temperature, photoperiod and photon flow density and then subjected to heat stress for 24 h at 37 °C, followed by a recovery period under normal conditions (21 ± 2 °C). The cycle was repeated. The chlorophyll a fluorescence intensity was measured, and the parameters of the JIP-test were calculated. The gas exchange was also evaluated. The JIP-test showed significantly different responses of the genotypes to heat stress. The parameters of photosystem I activity and the net assimilation of CO 2 increased during the first stress cycle in genotypes with a high expression of MT-sHSP23.6 and in non-transformed plants; however, the net assimilation of CO 2 decreased in genotypes with a low expression of MT-sHSP23.6. The data suggest that MT-sHSP23.6 participates in the heat tolerance mechanism, considering that the suppression of this protein resulted in greater physiological damage during heat stress.