Divergence of reactions to arsenic (As) toxicity in tobacco (Nicotiana benthamiana) plants: A lesson from peroxidase involvement

To evaluate the multiplicity of reactions to toxic metalloid arsenic (As) with specific emphasis on the role of plant peroxidases, a model plant Nicotiana benthamiana was cultivated in in vitro conditions at various doses of As (applied as As5+ up to 80 mu M). After 28-day cultivation, several physiological characteristics such as plant growth, photosynthetic pigment concentration, As concentration, peroxidase (POX) expression levels, and POX activity were evaluated. A newly sequenced gene for POX has been identified, that belongs to the Class III plant extracellular peroxidases, and its relationship to the genus Solanum as the most relative species has been confirmed. In the control and selected As treatments (20As, 50As, and 80As), newly identified POX expression and POX activity were continuously detected during the whole cultivation period. The plant reactions to As stress were distinguished into three groups: low As, moderate As, and high As. A tight relationship was found between the photosynthetic pigments and POX expression. Accumulation of As in roots and shoots showed correlations with POX activities. The results showed that the diversity of reactions depends on As dose and time exposure and indicate an interface of peroxidase functional role with other physiological processes in plants suffering from As toxicity.

Automated summary

The study found that plant responses to arsenic toxicity are diverse, depending on the dose of arsenic and duration of exposure. There is a close relationship between photosynthetic pigments and peroxidase expression, and the accumulation of As in roots and shoots correlates with peroxidase activity.