Effects of terbuthylazine on phytosiderophores release in iron deficient barley

• Terbuthylazine (TBA) reduced phytosiderophores (PS) release in Fe deficient barley.
• TBA treated iron deficient barley showed reduced expressions of PS related genes.
• Reduced cysteine (Cys) levels in TBA treated samples explained the lower PS release.
• The interferences on Cys content were due to TBA interference on ATPS and OASTL.

One of the main purposes of modern agriculture is to raise crop production by means of a proper application of herbicides. Nonetheless, the use of herbicides is causing some concerns associated to their persistence and accumulation in the environment. Notwithstanding the relevance of these aspects, little or no attention has been paid to the interferences that these chemicals and their residues can exert on iron (Fe) mineral nutrition of plants. To this purpose, we studied the effect of terbuthylazine (TBA) on the Fe-acquisition processes of Fe-deficient barley plants, by investigating some aspects related to phytosiderophores (PS) exudation and sulfur (S) metabolism. Results showed that plant growth, chlorophyll content expressed as SPAD index, PS release and the expression of genes involved in their secretion, uptake and biosynthesis were negatively affected. This response was associated with reduced cysteine concentrations, and it suggests that the TBA interferences on Fe-acquisition in barley are the consequence of the induced changes in S metabolism.

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