Determination of Cell Viability and DNA Fragmentation in Tomato Fruit Induced by Senescence and Heat Stress

Abstract:

Cell viability and DNA fragmentation analysis are essential markers for tomato fruit programmed cell death(PCD).The ion leakage detection and TUNEL assay of tomato fruit method were optimized in this study,and compared the effect of different concentrations of mannitol and water as a medium on determination of ion leakage.The ion leakage of tomato fruit discs was lower in 0.2 mol/L(0.3mol/L of mannitol solution,and became stable after 120 min.But the ion leakage in water increased continually within 240 min,from(23.95± 0.85)% to(63.95±0.35)%.The results showed that immersion of pericarp discs in 0.3mol/L mannitol,120 min shaking was suitable for detecting the ion leakage of tomato fruit.Cell death rate rised in red ripe tomatoes and 45 ℃ heat-treated mature green tomatoes.In situ TUNEL staining using hand slice for detecting DNA fragmentation of tomato fruit cells was simple and feasible,and TUNEL-positive nucleus were detected in senescence tomato fruit and heat-treated mature green tomato fruit,respectively.