Pumping iron, keeping FIT: How MYB30 regulates FIT stability during plant iron deficiency

The well-known cartoon character Popeye eats spinach for its high iron (Fe) content, which gives him the strength to deal with his nemesis, Brutus.Plants also rely on this critical element to grow properly.In the model plant Arabidopsis (A. thaliana), a pivotal transcription factor FER-LIKE IRON DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) helps plants respond to Fe-deficiency by inducing the expression of iron transporter genes, including FERRIC REDUCTASE OXIDASE2 (FRO2) and IRON TRANSPORTER1 (IRT1; Colangelo and Guerinot, 2004).When Fe stores are replenished, two BRUTUS-LIKE E3 ubiquitin ligases, BTSL1 and BTSL2, mediate the ubiquitination and degradation of FIT, thus preventing excessive iron uptake (Rodrguez-Celma et al. 2019).Surprisingly, even under Fe deficiency, the expression of BTSL1 and BTSL2 also increases (Rodrguez-Celma et al. 2019).This paradox raises the question of how FIT escapes the fate of being degraded under Fe deficiency, when it is needed the most.