Heavy Metal Stress Mechanism by Signaling Cascades in Plants

Effect On Plant Growth Under Stress

Heavy metals can affect on the growth of plants in a number of points and toxic effect at different levels of cell structure and function of the plants. Inhibition of the germination and root extension can be result of the interference with the cell division or with the cell elongation. It has been observed that the main pressure of heavy metals such as Zn, Cu, Co, Cd, Hg and Pb is the inhibition of the germination rate, root elongation and shoot and leaf growth (Munzurog and Geckil, 2002; Rascio et al., 2008; Hameed et al., 2016). The inhibition of root elongation in many instances is the most sensitive parameter of heavy metal toxicity (Schutzendubel et al., 2001; Hameed at al., 2015). In crop production Al toxicity is one of the major growth-limiting factors in acidic mineral soils (Panda et al., 2009). The root systems become stubby as a result of the inhibition of elongation to main axis points and lateral roots due to restricted cell division. The root become stunted and brittle and apices become swollen and damaged (Panda et al., 2009). It causes extensive root injury, especially in root cap region and hampers the mineral and water uptake; severity inhibition of root growth is a suitable indicator of genotypical differences in Al toxicity (reviewed by Rout et al., 2001; Hameed at al., 2016). Heavy metals interfere with cell division and therby reduce the growth of both root and shoot meristem. There Inhibition of mobilization of nitrogen and phosphorus during seedling growth has been observed in sinach on exposure to mercury (Hg) (Gothberg et al., 2004; Hameed et al., 2016). Under higher concentration of heavy metal exposure root and shoot growth declines and low pigment content (reviewed by Nazar et al., 2012; Hameed et al., 2016).