Influence of the Nitric Oxide on Root Tip Cells of Maize under Pb Stress

Wu Jiaye, Hao Ruizhi, Cao Yuan, Wang Xiaofeng, Song Han, Jing Yanping^*

College of Biological Sciences and Technology, Beijing Forestry University/National Engineering Laboratory for Tree Breeding, NDRC/Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, Beijing 100083, Chin

Abstract: Nitric oxide (NO) is a key signal molecule involved in multiple plant responses to diverse biotic and abiotic stresses including lead. The root tip cells of maize (Zea mays L.) were used in this study to explore the effect of Pb and the endogenous nitric oxide (NO)/reactive oxygen species (ROS) concentration of cells under Pb stress. The role of NO on Pb tolerance in root tip cells of maize was invested through supplement NO by sodium nitroprusside (SNP) or NO-specific scavenger 2-(4-carboxyphenyl)-4，4，5，5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). In this work， different dosages of Pb inhibited root growth and caused decreased cell viability in maize.Positive TUNEL signals were also detected， suggesting that Pb induced programmed cell death in maize root tip cells. Pb toxicity was accompanied by an increase in NO and ROS levels. The elimination of NO by cPTIO led to a decrease of ROS and also an attenuation of Pb-induced root cell PCD. The supplement of NO by SNP led to an increase of H2O2 and O2 –· and also enhanced the inhibitory effect of lead on maize root growth， whereas the cPTIO alleviated this toxicity by reduced H2O2 and O2 –· concentration. The results showed that Pb-induced NO promoted an increase in ROS accumulation and contributed to PCD and inhibition of root growth in maize.

CSTR: 32200.14.cjcb.2013.04.0011