Micronutrient Use Efficiency – Cell Biology of Iron and Its Metabolic Interactions in Plants - Nutrient Use Efficiency in Plants - page 138

Fig. 5.2 Regulation of Fe deficiency responses in (a) Strategy I and (b) Strategy II plants.
Rectangles indicate important regulatory transcription factors of the two Strategies and down-
stream Fe responsive genes. Arrows indicate positive or negative regulation. Abbreviations: bHLH
basic helix-loop-helix, FIT FER-like iron deficiency induced, EIN3/EIL1 ETHYLENE INSENSI-
TIVE 3/ETHYLENE INSENSITIVE 3-LIKE, PYE POPEYE, ILR3, BTS BRUTUS, IDEF iron
deficiency responsive element-binding factor, IRO iron-related transcription factor
regulatory protein named BRUTUS (BTS). BTS possesses three different domains,
one with putative E3 ligase activity, one for transcriptional regulation and one for
Fe binding. Unlike pye , bts mutants appear more resistant to Fe deprivation and
show a better growth in - Fe conditions, with longer roots and greener shoots. A