QUALITATIVE INVESTIGATION OF THE IRON DEFICIENCY RESPONSE IN DIFFERENT PLANT LINEAGES

Date

2023-8-28

Author

Gora, Desara

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Iron (Fe) is an essential micronutrient for plant nutrition and despite it being an abundant material on Earth its low bioavailability in calcareous soil leads to Fe deficiency in plants. To combat Fe deficiency, plants employ two different Fe uptake strategies, namely Strategy I and II. The hallmark of Strategy I response is reduction of Fe(III) to Fe(II) via a ferric reductase oxidase (FRO), rhizosphere acidification via a proton pump, and Fe(III) chelation via secondary metabolites (coumarins) secretion. To understand the extent of the Fe deficiency response in several plant species and its cross-lineage conservation we screened the plants for their response to Fe deficiency regarding coumarins accumulation, Fe reduction ability and rhizosphere acidification. Screened plants included ones whose growth was strictly restricted to either alkaline soil (calcicole) or acidic soil (calcifuge). To culture seeds in sterile conditions, various parameters were optimized. Half MS agar media was used to grow the plants with small seeds for which a surface sterilization method was established. Hydroponics was used to grow plants with big seeds for which surface sterilization was challenging. To induce Fe deficiency the plants were transferred to agar media and Hoagland’s solution without Fe for 14 days for legumes and 4-10 days for the rest. Our results showed that most plants have a conserved pattern of the Fe deficiency response with grasses employing Strategy II mechanisms and non-grasses employing Strategy I. However, calcifuge plants showed little to no rhizosphere acidification and coumarin secretion, whereas the calcicole species showed continuous coumarin secretion regardless of the Fe supply in the media and little to no rhizosphere acidification. FRO activity increased in all dicot species in response to Fe deficiency, regardless of their calcicole, calcifuge, or other status. This study found evidence that differential plant distribution on calcareous and acidic soils may be determined by the extent of their response to Fe deficiency, having important implications in plant ecophysiology.

Subject Keywords

Fe deficiency, Ferric chelate reductase activity, Rhizosphere acidification, Coumarin secretion, Calcifuge plant

URI

https://hdl.handle.net/11511/105489

Collections

Graduate School of Natural and Applied Sciences, Thesis