Differential Two-Dimensional Protein Patterns as Related to Tissue Specificity and Water Conditions in Brassica napus var oleifera Root System

Abstract

Differential two-dimensional protein patterns as related to tissue speci-ficty and water conditions were investigated within Brassica napus var okeifea root system. The different parts of the root system (tap root, lateral roots, and drought-induced short roots) were analyzed under various moisture regim (regular watering at field capacity, progressive drought stress, and rewatering). Tissue speciflcity was evident from 25 differences in protein patterns (qualitative and quantitative) between well-watered lateral and tap roots. Twice as many polypeptides (52) were drought-affected and the response to the water stress was shown to be imilar in both root types. In addition, more than half of the polypepties detected as organ-specific were affected by drought. Based upon the trend of variation observed under drought and rehydration, three categories of polypeptides could be ddened that might be differently involved in drought susceptibilit or tolerance. A highly differentiated protein pattern characterized the drought-induced short roots. This pattern appeared as far from the watered as from the water-stressed normal roots. In particular, 13 unique polypeptides were detected which could be relevant to their adaptive morphogenesis and/or their specifc drought tolerance induction. Upon rehydration, their polypeptide pattern and their specific morphology returned to a nornil well-watered lateral root type.