title: Physiological responses of biomass allocation, root architecture, and invertase activity to copper stress in young seedlings from two populations of Kummerowia stipulacea (maxim.) Makino.
abstract: In the current study, we hypothesize that mine (metallicolous) populations of metallophytes form a trade-off between the roots and shoots when under copper (Cu) stress to adapt themselves to heavy metal contaminated habitats, and thus, differ from normal (non-metallicolous) populations in biomass allocation. To test the hypothesis, two populations of the metallophyte Kummerowia stipulacea, one from an ancient Cu mine (MP) and the other from a non-contaminated site (NMP), were treated with Cu(2+) in hydroponic conditions. The results showed that MP plants had higher root/shoot biomass allocation and more complicated root system architecture compared to those of the NMP plants when under Cu stress. The net photosynthetic capacity was more inhibited in the NMP plants than in the MP plants when under Cu stress. The sugar (sucrose and hexose) contents and acid invertase activities of MP plants were elevated while those in NMP plants were inhibited after Cu treatment. The neutral/alkaline invertase activities and sucrose synthase level showed no significant differences between the two populations when under Cu stress. The results showed that acid invertase played an important role in biomass allocation and that the physiological responses were beneficial for the high root/shoot biomass allocation, which were advantageous during adaptive evolution to Cu-enriched mine soils.
authors.affiliation: School of Resource and Environmental Sciences, Wuhan University, Wuhan, Hubei 430079, People׳s Republic of China.
authors.forename: Luan
authors.initials: L
authors.lastname: Zhang
authors.affiliation: School of Resource and Environmental Sciences, Wuhan University, Wuhan, Hubei 430079, People׳s Republic of China.
authors.forename: Yuxue
authors.initials: Y
authors.lastname: Pan
authors.affiliation: School of Resource and Environmental Sciences, Wuhan University, Wuhan, Hubei 430079, People׳s Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Lv
authors.affiliation: School of Resource and Environmental Sciences, Wuhan University, Wuhan, Hubei 430079, People׳s Republic of China. Electronic address: ztixong@whu.edu.cn.
authors.forename: Zhi-ting
authors.initials: ZT
authors.lastname: Xiong
mesh_terms: D000222:Adaptation, Physiological; D018533:Biomass; D003300:Copper / Q000633:toxicity*; D004789:Enzyme Activation / Q000187:drug effects; D007887:Fabaceae / Q000187:drug effects*; D006601:Hexoses / Q000032:analysis; D018527:Hydroponics; D010788:Photosynthesis / Q000187:drug effects; D018517:Plant Roots / Q000187:drug effects*; D036226:Seedlings / Q000187:drug effects*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000633:toxicity; D013312:Stress, Physiological; D013395:Sucrose / Q000032:analysis; D043324:beta-Fructofuranosidase / Q000378:metabolism*
chemical_list: D006601:Hexoses; D012987:Soil; D012989:Soil Pollutants; D013395:Sucrose; D003300:Copper; D043324:beta-Fructofuranosidase
keywords: Acid invertase; Biomass allocation; Kummerowia stipulacea; Photosynthesis; Root architecture; Sugar