Evolutionary analysis of iron (Fe) acquisition system in Marchantia polymorpha

Area of Science:

• Plant Biology
• Biochemistry
• Evolutionary Biology

Background:

• Vascular plants utilize distinct strategies for iron (Fe) acquisition: strategy I (reduction-based) for Fe(2+) and strategy II (chelation-based) for Fe(3+).
• The iron uptake mechanisms in bryophytes, early land plants, remain poorly understood.

Purpose of the Study:

• To elucidate the iron acquisition strategy employed by the liverwort Marchia polymorpha.
• To investigate the molecular basis of iron uptake in a representative non-vascular land plant.

Main Methods:

• Iron isotope fractionation analysis to determine the Fe acquisition pathway.
• Enzyme activity assays for ferric chelate reductase and proton ATPase under varying Fe conditions.
• Gene expression analysis (knockdown and overexpression) of identified ZIP homologs.

Main Results:

• Marchia polymorpha employs a reduction-based iron acquisition strategy, confirmed by isotope fractionation.
• Increased ferric chelate reductase and proton ATPase activity were observed under iron deficiency.
• Knockdown of MpZIP3 impaired growth in low iron, while overexpression enhanced iron content in high iron conditions, indicating its role in iron uptake.

Conclusions:

• The non-vascular liverwort Marchia polymorpha utilizes strategy I for iron acquisition.
• This ancient iron uptake system may have been present in the common ancestor of all land plants.
• The mechanism was likely co-opted from the gametophyte to sporophyte generation during land plant evolution.