Changes in morphology, proline content, and palatability to Helix aspersa, in Plantago lanceolata in response to transplantation and polluted soil

Abstract

High concentrations of heavy metals are a cause of stress in plants, many of which respond by accumulating high levels of the amino acid proline. Tolerant and intolerant plants may vary in their response, and this may be reflected in the palatability of their leaves to herbivores. Plantago lanceolata plants were collected from four sites showing a range of lead pollution, and were tested for tolerance to lead. Plants from one polluted and one unpolluted site were grown in soils with and without lead for four weeks, and their leaves were offered to Helix aspersa in palatability tests. The proline concentration in these plants leaves was determined, and some morphological features were examined. Plants from each site varied in lead tolerance, and this characteristic showed no clear relationship to the lead concentration of their site of origin. This was considered to be the result of gene flow between plants on small areas of polluted and unpolluted ground. A possible link between increased palatability and high proline concentration was established. High proline concentration was related to recent transplantation more strongly than to lead concentration in the soil used.