“…In plants, the respective enzymes for oxidative burst caused by pathogen attack or mechanical wounding are primarily ascribed to the plasma membrane-located NADPH oxidases, homologs of the mammalian gp 91phox respiratory burst NADPH oxidase subunit (Orozco-Cardenas et al, 2001;Torres et al, 2002;Sagi et al, 2004). ROS generated by plasma membrane-located NADPH oxidases also play an important role in regulating plant growth and development, including the growth of root hair and pollen tube (Foreman et al, 2003;Potocky et al, 2007), stomata closure (Kwak et al, 2003;Cho et al, 2009;Srivastava et al, 2009), lignification in differentiating xylem vessels (Barceló, 2005), seed after-ripening (Muller et al, 2009), and seed dormancy (Liu et al, 2010). In addition, exogenous H 2 O 2 has a positive effect on the cotton fiber initiation , and the H 2 O 2 generated from extracellular peroxidases and CuZn-superoxide dismutase (SOD) is required for seed germination in Pisum sativum (Kranner et al, 2010) and for the development and lignification of the secondary walls of tracheary elements in the Zinnia cell-culture system (Karlsson et al, 2005).…”