title: Interactions among Fe2+, S2-, and Zn2+ tolerance, root anatomy, and radial oxygen loss in mangrove plants.
abstract: Root anatomy, radial oxygen loss (ROL), and tolerances to ferrous (Fe(2+)), sulphide (S(2-)), and zinc (Zn(2+)) ions were investigated in seedlings of eight species of mangrove, including three pioneer species, three rhizophoraceous and two landward semi-mangrove species. The results showed an interesting co-tolerance to Fe(2+), S(2-), and Zn(2+). The three rhizophoraceous species (Bruguiera gymnorrhiza, Kandelia obovata and Rhizophora stylosa), which possessed the thickest lignified exodermis and the 'tightest barrier' in ROL spatial pattern, consistently exhibited the highest tolerance to Fe(2+), S(2-), and Zn(2+). B. gymnorrhiza could directly reduce ROL by increasing lignification within the exodermis. Such an induced barrier to ROL is a probable defence response to prevent further invasion and spread of toxins within plants. The data also indicated that, in B. gymnorrhiza, Fe(2+) or S(2-), or both, induced a lignified exodermis that delayed the entry of Zn(2+) into the roots and thereby contributed to a higher tolerance to Zn(2+). This study provides new evidence of exclusive strategies of mangrove seedling roots in dealing with contaminations. The information is also important in the selection and cultivation of tolerant species for the bioremediation of contaminated waters or soils.
authors.affiliation: State Key Laboratory for Bio-control, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Cheng
authors.forename: Dan-Ting
authors.initials: DT
authors.lastname: Chen
authors.forename: Nora Fung-Yee
authors.initials: NF
authors.lastname: Tam
authors.forename: Gui-Zhu
authors.initials: GZ
authors.lastname: Chen
authors.forename: Shi-Yu
authors.initials: SY
authors.lastname: Li
authors.forename: Zhi-Hong
authors.initials: ZH
authors.lastname: Ye
mesh_terms: D005296:Ferrous Compounds / Q000378:metabolism*; D017665:Hydroxyl Radical / Q000378:metabolism*; D018517:Plant Roots / Q000033:anatomy & histology / Q000378:metabolism*; D043982:Rhizophoraceae / Q000033:anatomy & histology / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
chemical_list: D005296:Ferrous Compounds; D013440:Sulfides; D017665:Hydroxyl Radical; D015032:Zinc