Different efficiencies in organic P exploitation of two Italian alfalfa (Medicago sativa) landraces involving a possible adaptation pattern of the phytase encoding MsPHY1 gene

The agricultural practice of manure cropping can result in the accumulation of surplus phosphorus (P) in soils with consequent losses by leaching. Two Italian alfalfa landraces originating from intensive (“Cremonese”) versus extensive (“Senese”) cattle farming regions were studied in order to investigate their variation for (a) efficiency in exploiting different P sources–farm dairy effluents (FDE), phytic acid (Phy), and inorganic P (IP)–in a lysimeter trial, and (b) the sequence of the MsPHY1 gene, which encodes a root extracellular phytase, releasing inorganic P for plant growth. The Cremonese landrace showed higher P uptake efficiency than Senese in the FDE and Phy treatments and lower inorganic P losses in leachates, particularly in the FDE treatment. The MsPHY1 gene was highly variable and the variation was not neutral but maintained by selection. Two non-synonymous SNPs, in particular SNP970, located in a motif containing conserved metal-ligating residues, produced alternative alleles with frequency differences between landraces. A pattern of adaptive response for the ability to use organic P forms is discussed at both the physiological and genetic levels.