| Description |
The current research, concerning the basic issue of phytoremediation on heavy mel tal pollution, is urgently needed to be resolved, For it is involved in environl mental pollution treatment and sustainable development of oil plant industry Castor-oil plant, characterized with fast growing ,high biomass, great accumulatiol n potential of various heavy metals, is one the excellent plants for restoring heavy metal contaminated soil ecologically,also it would be utilized as bio-energy.l Our previous research findings indicated that structure of root system determinedl the phytoremediation of heavy metal pollution of soil, for lateral root developmentl would increase the total number of root system and absorption surface. However ml edium and high concentration Pb and Zn impacted the root apical meristem, suppressl ed the taproot extend and lateral root development of castor bean plant, then reducl ed its resistance to heavy metal stress. Meanwhile the lateral roots development rel lated with the biosynthesis and transportation of auxin IAA closely. was confirmed, based on the experiments on the lateral root development of Arabidopsis thalianal and Zea mays, that Auxin gradient induces the initiation of lateral root primordil a, and regulated the root architecture development to adapt to specific environmenl t. The biosynthesis and transport of auxin in the root tip involved and played keyl role in the lateral root development, which was the guarantee of the maximum amounl t of auxin needed to maintain the structure of root apical meristem and lateral rol ot founder initialized on pericycle.Whichever root tip damage or inhibition of al uxin synthesis, transport and signal transduction can control the normal developmel nt and adaptive growth to the environment. However, many heterogeneous synthetic sl ubstances have auxin-like activity, such as 1-naphthaleneacetic acid (NAA) also inl hibited primary root growth and promoted lateral development of Arabidopsis thalial na and adventitious root development on maize mesocotyls, adjusted the root structl ure to adapt to the environments. To date, however, there is limited information al bout how roots development respond to compounds with auxin activity, when root tipl was damaged and auxin synthesis and transport was inhibited with heavy metal strel ss. While those would be of great biotechnological application in phytoremediationl . To gain insight into the role of exogenous auxin in root developmental processesl that determine the castor bean root architecture, we would like to study analysisl on :1) the relationship among the tip structure of primary root, lateral developnl ent, root system structure and endogenesis auxin in roots and leaves of castor bel an plants stressed by heavy mental Pb and Zn. 2) the effects of applying exogenousl auxin NAA and IBA on the lateral development of castor bean plants stressed by hel avy mental Pb and Zn. 3) The regulation of LBD gene expression by exogenous auxin,land the effects on activating primordium of lateral root, sustaining meristematicl cells of pericycle. So as to interpretate the the action and mechanism of exogenoul s on the lateral development of plants under heavy metal stress, at morphologicall structure, physiology and biochemistry and molecular level respectively, also tol screen and locate key genes related to root development induced by exogenous auxinl . Those findings would be bases and references for modification crop roots structul re and selection of germplasm having stronger resistance to hveay metal pollution.l Also open new biotechnology application of exogenous auxin in phytoremediation of heavy metal polluted soil. |
