A Rapid 96 Well Plate-Based Screen for Phytosiderophores: A Test Using Historical Varieties (1910-1997) of Hard Red Spring Wheat.

Iron is one of the essential nutrients plants need to grow. It is known that plants use iron as Fe(II).  Under conditions of iron deficiency graminaceous plants (grasses, cereals and rice) excrete chelators called phytosiderophores (PS) with the principal function of forming PSFe(III) complexes in soils which are then taken up  and converted to Fe(II) within the plant.  The aims of this research were to first, develop a rapid screening tool for the quantification of PS in root exudates, and second, to use this method to identify the iron efficiency of 50 historical varieties (1910-1997) of hard red spring wheat (HRSW). We hypothesize that, under iron deficiency, the oldest wheat varieties will release more PS than the newer, as the first are likely better adapted to less fertile soils.  To test our hypothesis and the screening platform, wheat plants were grown hydroponically in a growth chamber in solutions containing adequate (50microM) and low (10 microM) iron.  Jars containing each variety were arranged in a randomized complete block design from which solutions were collected weekly, for 4 weeks, and screened for PS concentration using a newly develop, high-throughput, 96 well plate-based PS detection platform. The experiments were repeated 3 times, each block representing an experimental replicate.  At the end of each experiment, roots and shoots were dried, weighed, ashed, acid digested and micro and macronutrient content determined.  This project led to the identification of new iron-efficient varieties of wheat using a new high-throughput phytosiderophore screening platform which can be used for the rapid screening and discovery of other agronomically-important graminaceous crop plants.