Proteomic Analysis of Heat Stress Response in Leaves of Radish (Raphanus sativus L.)

High temperature is one of the most important abiotic factors influencing plant growth and development. Radish is a cool season vegetable crop sensitive to higher temperatures. Heat injuries may affect plant growth, and interfere with formation and thickening of the fleshy taproot. To characterize the heat-stress response in radish, 30-day-old radish seedlings were exposed to a temperature of 40 A degrees C. Leaf samples were then collected from the seedlings at 0 h, 12 h and 24 h after temperature exposure. Proteins extracted from leaves were analyzed with two-dimensional electrophoresis (2-DE), and differentially expressed protein spots were identified by mass spectrometry (MS). In total, 11 differentially expressed proteins were identified successfully by MALDI-TOF MS. Of these, four were heat shock proteins (HSPs), four were related to energy and metabolism, two were related to redox homeostasis, and one was related to signal transduction. These proteins were analyzed further for mRNA levels, corresponding to differential levels of gene expression. The result showed that gene expression profiles at the transcriptional level were not completely consistent with those at translational levels. The differentially expressed heat stress response proteins identified, like small heat shock proteins together with energy and metabolism-related proteins, provide new insights into the molecular basis of plant responses to high temperature stresses in radish.