title: Physiological and biochemical responses to high Mn concentrations in two contrasting Populus cathayana populations.
abstract: We exposed the cuttings of Populus cathayana to Hoagland's solution containing four different manganese (Mn) concentrations (0, 0.1, 0.5 and 1mM) in a greenhouse to characterize the physiological and biochemical basis of Mn resistance in woody plants. Two contrasting populations of P. cathayana were used in our study, which were from the wet and dry climate regions in western China, respectively. The results showed that Mn treatments significantly decreased chlorophyll content and growth characteristics, including shoot height, basal diameter, biomass accumulation and total leaf area in the two populations. Mn treatments also significantly increased the levels of abscisic acid (ABA), polyamines and free amino acids especially proline (Pro), histidine (His) and phenylalanine (Phe) available for cellular signaling and heavy metal chelation. In addition, high Mn concentrations also caused oxidative stress indicated as the accumulation of hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA) contents. On the other hand, there were different responses to Mn stress between the two contrasting populations. Compared with the dry climate population, the wet climate population accumulated more Mn in plant tissues especially in leaves; it showed lower tolerance index and more pronounced decrease in growth and chlorophyll contents. The wet climate population not only accumulated less ABA, putrescine and free amino acids, but also exhibited lower activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), thus suffering from more serious oxidative damage. Therefore, our results showed that the wet climate population was more susceptible to Mn stress than the dry climate population.
authors.affiliation: Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China.
authors.forename: Yanbao
authors.initials: Y
authors.lastname: Lei
authors.forename: Helena
authors.initials: H
authors.lastname: Korpelainen
authors.forename: Chunyang
authors.initials: C
authors.lastname: Li
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D060387:Ascorbate Peroxidases; D002681:China; D002734:Chlorophyll / Q000378:metabolism; D002980:Climate; D008345:Manganese / Q000633:toxicity*; D010544:Peroxidases / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism; D032107:Populus / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000596:Amino Acids; D011073:Polyamines; D002734:Chlorophyll; D008345:Manganese; D000040:Abscisic Acid; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D013482:Superoxide Dismutase