Lead-induced Apoptosis And Related Signal Molecules In Root Tip Cells Of Maize

With increasingly heavy metal pollution, more and more attention was paid to the toxic effect and mechanism of plant response to heavy metals. In this thesis, we found that different dosages of Pb2+inhibited root growth and caused decreased cell viability in maize (Zea mays L.). Positive TUNEL signals were also detected, suggesting that Pb2+induced apoptosis in maize root tip cells. Pb2+toxicity was accompanied by an increases in nitric oxide (NO) and reactive oxygen species (ROS) levels. Inhibiting NO accumulation with an NO-specific scavenger cPTIO prevented increases of NO and ROS as well as subsequent cell death in root tips. Biochemical measurements results showed that the role of an NO donor(SNP) was in contrary to that of cPTIO. SNP lead to an increase of H2O2, and O2-. and also enhanced the inhibitory effect of lead on maize root growth. Using Calcium fluorescence probe Fluo-3/AM, we found lead induced a rapid decline of intracellular calcium concentration. Transient calcium increase was found when exogenous calcium was added. This work indicated that Pb2+-induced NO promoted an increase in ROS accumulation and contributed to apoptosis in maize root tip cells. In addition, as an important signal molecules, Intracellular calcium concentration decreased under lead stress and exogenous calcium could alleviate lead stress. The result provide clues of plant response signal processes under lead stress and provide a theoretical basis for alleviating lead pollution.