Synthesis of Organic Iodine Compounds in Sweetcorn under the Influence of Exogenous Foliar Application of Iodine and Vanadium

Abstract

A human’s diet should be diverse and rich in vitamins, macro- and microelements essential for the proper functioning of the human body. Globally, a high percentage of the human population suffers from malnutrition, deficiencies of nutrients and vitamins also known as the problem of hidden hunger. This problem it is not only common in poor countries, but also occurs in developed countries. Iodine is a nutrient crucial for the proper functioning of the human and animal body. For plants, it is referred to as a beneficial element or even a microelement. The design of the biofortification experiment was determined on the basis of the interaction of iodine and vanadium (synergistic interaction in marine algae), where vanadium-dependent iodoperoxidase catalyzes apoplastic oxidation of iodine, resulting in high efficiency of iodine uptake and accumulation in brown algae (Laminaria digitate). Three independent experiments (Exp.) were carried out with the foliar application of vanadium (V) and iodine (I) compounds. The main differences between the experiments with the adapted proper corn biofortification method were the different application stage between the individual experiments, the application intervals and the dose of the iodine–vanadium compound. In each experiment, the accumulation of iodine and vanadium in the grain was several times lower than in the leaves. The combination iodine and vanadium significantly increased the accumulation of iodine in the grain in the case of applying V with inorganic iodine compounds, and a decrease in the accumulation of I after applying V with organic iodine compound —especially in Exp. No. 3. In grain, the highest content of I−, IO3− was in combination with the application of 2-iodobenzoic acid (products of its metabolism). In most of the tested combinations, vanadium stimulated the accumulation/synthesis of exogenous/endogenous 5-iodosalicylic acid (5ISA) and 2-iodobenzoic acid (2IBeA), respectively, and decreased the content of 2,3,5-triiodobenzoic acid (2,3,5-triIBeA) in leaves and grains. The tested compounds I and V and the combinations of their application had a diversified effect on the vitamin C content in the grains. Vanadium in the lower dose of 0.1 µM significantly increased the sugar content in the grain.

Iodine Biofortification of Dandelion Plants (Taraxacum officinale F.H. Wiggers Coll.) with the Use of Inorganic and Organic Iodine Compounds

“…However, in both the leaves and roots of dandelion plants from that combination, the presence of low levels of 5-ISA and 3,5-diISA has been detected, which indicated that these iodosalicylates are endogenously synthesized in these plants. These results confirm previous reports on the synthesis of iodosalicylates in higher plants, without exogenous iodine application, as demonstrated for tomato [17], lettuce [18] and sweet corn [19].…”

“…It is worth mentioning that, apart from iodosalicylates, there also reports evaluating the applicability of other organoiodine compounds, such as iodobenzoates, in plant cultivation [34,40]. Interestingly, in the studies with corn cultivation, the effect of iodine biofortification after the application of 2-IBeA was even similar to that obtained for KI; however, the applied doses were relatively low (10 µM I [19]).…”

“…The second most effective compound, in terms of increasing iodine content in dandelion plants, was 5-iodosalicylic acid. Also, Grzanka et al [19] reported the higher efficiency of potassium iodide, followed by 5-ISA, in improving iodine levels in young corn plants. The iodine level in both leaves and roots of dandelion plants after the application of 5-ISA was higher than that after using inorganic KIO 3 , particularly at the increased dose (50 µM).…”

“…However, the possible root uptake of organic forms of iodine by higher plants and its further translocation and accumulation have recently been more intensely studied providing some promising results, in terms of the iodine biofortification process. It has been revealed that among tested exogenous organoiodine compounds, those being derivatives of salicylic acid, such as 5-iodosalicylic acid (5-ISA) and 3,5-diiodosalicylic acid (3,, are efficiently taken up and pose no exceptional toxicity towards plants [17][18][19]. What is more, 5-ISA and 3,5-diISA increased the health-promoting properties of lettuce plants, as demonstrated in in vitro studies on human cancer cell lines [20].…”

Iodine Biofortification and Seaweed Extract-Based Biostimulant Supply Interactively Drive the Yield, Quality, and Functional Traits in Strawberry Fruits

“…Iodine (I) is a crucial component of the human organism [ 18 ]. It is implicated in thyroid hormone synthesis, metabolic regulation processes, and the main physiological functions of the organism [ 19 , 20 , 21 , 22 , 23 ].…”