Comparative antioxidative responses and proline metabolism in two wheat cultivars under short term lead stress.

This study investigated antioxidative response and proline metabolism in two wheat cultivars (Tritium aestivum Xihan 2 (Xihan) and Ningchun 4 (Ningchun)) under Pb(NO(3))(2) stress. The constitutive H(2)O(2) scavenging enzyme activities and proline content in the leaves of drought-tolerant Xihan are higher than those in drought-sensitive Ningchun. Higher Pb concentration reduced chlorophyll content in both cultivars, but Ningchun was more sensitive to lead toxicity than Xihan. The higher activities of antioxidant enzyme and the significant proline accumulation provide protection for two wheat cultivars against lead toxicity, resulting in unaltered MDA content. Analysis of enzyme activities showed that the accumulation of proline induced by lead stress is due to the increases of OAT and GK activities in Xihan seedlings, and to the increase of GK activity in Ningchun leaves. Therefore, the different mechanism of proline metabolism was associated with increased proline levels in two wheat cultivars when exposed to lead stress.