Strobilurins as growth-promoting compounds: How Stroby regulates Arabidopsis leaf growth

Strobilurins are an important class of agrochemical fungicides used throughout the world on a wide variety of crops to protect against fungal pathogens. In addition to their protective role against pathogens, they are reported to also positively influence plant physiology. In this study, we analyzed the effect of Stroby® WG, a commercially available fungicide consisting of 50% (w/w) kresoxim-methyl (KM) as active strobilurin compound, on Arabidopsis plant growth. Treatment of seeds or seedlings with Stroby resulted in larger leaves due to an increase in cell number. Transcriptome analysis of Stroby-treated rosettes demonstrated an increased expression of genes involved in redox homeostasis, iron metabolism and sugar transport. Stroby treatment strongly induced the expression of the subgroup Ib basic helix-loop-helix (bHLH) transcription factors, which have a role in iron homeostasis under iron-limiting conditions.