A simple and rapid method for determination of lignin in plant tissues - its usefulness in elicitor screening and comparison to the thioglycolic acid method
Richard R. StangeJr and Roy E. McDonald
Postharvest Biology and Technology Vol: 15 Issue: 2 Pages: 185-193
1999
บทคัดย่อ
Lignification of injuries is an important component of a plant's defense against postharvest diseases. Currently available methods for determination of lignin are slow and tedious. We describe a method to rapidly quantify lignin in plant tissue discs based on measurement of color difference following selective staining with Schiff's reagent. The effect of elicitor treatment on accumulation of lignin at 30°C was evaluated using storage tissues of four plants. Root tissues of daikon, turnip and sweet potato all exhibited increased lignification in response to elicitation with pectinase, chitosan or a yeast extract. Acorn squash tissue responded only to pectinase. Squash tissue elicited and then held at 28°C for 18 h developed considerable resistance to infection by Penicillium italicum. Accumulation of lignin over time was determined by both the color difference method and the thioglycolic acid (TGA) method. These two methods gave very different impressions of the accumulation of lignin over time. However, each method gave very similar results on all four plants tested. As measured by the color difference method, lignin accumulation became apparent only 4 h after elicitation and the lignification process was complete within 24 h. In contrast, lignin accumulation by the TGA method was much slower, increases were not evident until 8¯12 h after elicitation, and lignin continued to accumulate for a further 36 h. The difference between the results obtained with these two methods may be explained by the solubility of the lignin when first formed.