Efficient Cold Tolerance Evaluation of Four Species of Liliaceae Plants through Cell Death Measurement and Lethal Temperature Prediction

Abstract

Although Liliaceae are valuable resource plants with medicinal and edible uses, techniques for evaluating their tolerance to various abiotic stresses are very limited. This study evaluated the cold tolerance using visual inspection, electrolyte leakage, and Evan’s blue assay. Visual inspection of the responses to different temperatures, using a temperature range of 4 to −12 °C, showed that Scilla scilloides was receive the least damage. However, electrolyte leakage tests showed slightly different results from visual inspection. The median lethal temperature (LT50) was expected to be between −4 and −8 °C. The LT50 was considered a measure of damage due to electrolyte leakage in plant cold tolerance evaluation. As a result of predicting the lethal temperature using the logistic regression equation, the average LT50 of the four plants was −9.0 °C. The species with the lowest LT50 was measured for Hosta plantagines (−11.14°C), whereas the highest LT50 was measured for Hemerocallis fulva (−7.14°C). As a result of the Evan’s blue assay, it was found that cell necrosis occurred when the plants were exposed to low temperatures. Visual observation showed that more than 50% of the three plants’ cells, except for H. plantaginea, were stained blue even at 8 °C. From this result, H. plantaginea was judged to have strong low-temperature tolerance. At −12 °C, more than 50% of the four Liliaceae plants were colored blue, and the LT50 value was expected to be below −12 °C. The reducing sugar content, an indicator of plant cold tolerance, was the highest in H. plantaginea, followed by S. scilloide and H. longipes. Combining the three methods, H. plantaginea had the highest cold tolerance, followed by H. longipes, S. scilloides, and H. fulva. The results of this study will be widely used in selecting cold-tolerant useful resource plants.