Abstract
Iron (Fe) is an essential micronutrient for plant development as it participates in key processes like photosynthesis and chloroplast formation. In general, Fe is present in large quantities in soils but its bioavailability dramatically decreases in alkaline/calcareous soils. Thus, plants have developed different strategies to take up iron from the soil, which are tightly regulated by a coordinated cascade of transcription factors, mainly from the family bHLH. This cascade allows plants to modulate Fe availability, inducing its uptake when Fe is limiting and blocking its absorption when present in excess to prevent Fe toxicity. MYB28 and MYB29 are two R2R3-MYB transcription factors known to be master regulators of glucosinolate biosynthesis. In addition, they are also involved in Arabidopsis response to sulfur deficiency. In our research group, we also observed that MYB28 and MYB29 are positive regulators of ammonium tolerance. In particular, the double mutant myb28myb29 showed ammonium sensitivity, as it displays reduced growth and chlorosis under ammonium nutrition (Coleto et al., 2021). This phenotype was independent of glucosinolate metabolism and was associated with the ammonium-induced alterations in Fe homeostasis. Altogether, these two transcriptions factors emerge as an important hub for nutrient coordination in Arabidopsis. Following this observation, in the present work, we have evaluated the potential direct involvement of MYB28 and MYB29 in Arabidopsis response to Fe deficiency. To do so, we used, among others, physiological studies, metabolic and gene expression analysis.References:Coleto I. et al. (2021) Arabidopsis thaliana transcription factors MYB28 and MYB29 shape ammonium stress responses by regulating Fe homeostasis. New Phytol. 229: 1021-1035Funding Acknowledgement:Consolidated Groups programme (IT1560-22) of the Basque Government (DM, MBGM), the projects PID2020-113385RB-I00 and TED2021-132279B-I00 and the grant PRE2018-085268 funded by MCIN/AEI/10.13039/501100011033 and, as appropriate, by “ERDF A way of making Europe”, by the “European Union NextGenerationEU/PRTR” or by “ESF Investing in your future”.