Iodosalicylates and iodobenzoates supplied to tomato plants affect the antioxidative and sugar metabolism differently than potassium iodide

Iodine is considered as a beneficial element for plants. As compared to the mineral form of iodine, the effect of organoiodine compounds on physiological and biochemical processes in plants is weakly recognized. This study describes the influence of different forms of iodine – mineral as KI and organic as iodosalicylates and iodobenzoates on the antioxidative and sugar metabolism of tomato plants. Plants were treated with KI and with the following organoiodine compounds: 5-iodosalicylic acid (5-ISA), 3,5-diiodosalicylic acid (3,5-diISA), 2-iodobenzoic acid (2-IBeA) and 4-iodobenzoic acid (4-IBeA). The effect of salicylic acid (SA) and benzoic acid (BeA) on plants was also tested. The plants revealed a lower tolerance to 3,5-diISA, 4-IBeA and slightly to BeA as compared to control. Tested compounds did not affect the content of ascorbic (AA) and dehydroascorbic (DHA) acid. All tested compounds, with the exception of 2-IBeA, did not affect the content of phenols, phenylpropanoids and anthocyanins in leaves. Tested compounds variously modified the activity of catalase (CAT), ascorbic peroxidase (APX) and peroxidase (POX) in leaves and roots. The content of soluble sugars in tomato leaves and roots varied depending on the combination, with a noticeable tendency to increase after the application of organoiodine compounds.