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Figure 1. Gradient of cold sensitivity in representative Solanum species based on electrolyte leakage analysis. Leakage of cellular electrolytes was measured on leaf disks of plants at the mid-vegetative stage before and after exposure to chilling (13°C, top panel) or above-freezing (2°C, bottom panel) temperatures. Electrolyte leakage index (ELI) is the cellular electrolyte leakage ratio between cold-treated and control plants. An ELI = 1 indicates no significant leakage of electrolytes due to cold, while ELI >1 indicates significant leakage due to cold. Means (±SE, n = 4) are significantly greater than 1.5 (arbitrary cutoff level) at P < 0.001 (***) or P < 0.01 (**).
