Physiological highlights of manganese toxicity symptoms in soybean plants: Mn toxicity responses.
Manganese (Mn) is an essential element for plants; however, high concentrations in certain soil conditions can cause toxicity symptoms in the plant tissue. Here, we describe Mn toxicity symptoms and Mn toxicity responses in soybean plants. Soybean plants exposed to excess Mn showed reductions in the CO2assimilation rate and stomatal conductance, which in turn resulted in decreased shoot biomass. Furthermore, peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activity were higher in plants grown with the highest Mn concentration. The Mn doses increased the activity of antioxidant enzymes such as CAT, POD, and SOD. The toxicity symptoms presented by the leaves included hypertrophying of the adaxial epidermis and the formation of necrotic areas with purple-colored veins. Dramatic movement of calcium from the healthy region to the purple-colored necrotic region was observed, as was the exit of potassium from the necrotic area to the healthy region of the tissue. The high activities of POD and SOD in the presence of high Mn compartmented in the roots was the main physiological responses at high Mn uptake by soybean plants.
USP - University of São Paulo, Center for Nuclear Energy in Agriculture, Postal Code 13416-000, Piracicaba, SP, Brazil. Electronic address: elciokw@yahoo.com.br.
Elcio Ferreira
EF
Santos
UNESP - São Paulo State University, Postal Code 15385-000, Ilha Solteira, SP, Brazil. Electronic address: santinijmk@gmail.com.
José Mateus
JM
Kondo Santini
UNESP - São Paulo State University, Postal Code 15385-000, Ilha Solteira, SP, Brazil. Electronic address: amandappaixao@yahoo.com.br.
Amanda Pereira
AP
Paixão
UNESP - São Paulo State University, Postal Code 15385-000, Ilha Solteira, SP, Brazil. Electronic address: enes@agr.feis.unesp.br.
Enes Furlani
EF
Júnior
USP - University of São Paulo, Center for Nuclear Energy in Agriculture, Postal Code 13416-000, Piracicaba, SP, Brazil. Electronic address: jlavres@usp.br.
José
J
Lavres
UNESP - São Paulo State University, Postal Code 17602-496, Tupã, SP, Brazil. Electronic address: marcelocampos@tupa.unesp.br.
Marcelo
M
Campos
UNESP - São Paulo State University, Postal Code 15385-000, Ilha Solteira, SP, Brazil; UNESP - São Paulo State University, Postal Code 17602-496, Tupã, SP, Brazil. Electronic address: andrereis@tupa.unesp.br.
André Rodrigues Dos
AR
Reis
D000975:Antioxidants / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002374:Catalase / Q000187:drug effects / Q000378:metabolism; D008345:Manganese / Q000378:metabolism / Q000633:toxicity*; D018977:Micronutrients / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D013025:Glycine max / Q000187:drug effects* / Q000502:physiology*; D013312:Stress, Physiological / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism; D014510:Urease / Q000378:metabolism
D000975:Antioxidants; D018977:Micronutrients; D002245:Carbon Dioxide; D008345:Manganese; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase; D014510:Urease; D011188:Potassium; D002118:Calcium
Antioxidative stress; Energy-dispersive X-ray spectroscopy; Gas exchange parameters; Manganese phytotoxicity; Mineral plant nutrition