Can Triticum urartu be identified by pollen analysis? Implications for detecting the ancestor of the extinct domesticated two-grained einkorn-like wheat

Abstract

The domestication of the one-grained einkorn (Triticum monococcum) in the Near East is relatively well-known. However, an independent two-grained einkorn-like domestication has been archaeobotanically detected and scarce information is available. Triticum urartu, a wild wheat, was not fully described until the 1970s because the phenology does not allow distinguishing it easily from wild einkorn (Triticum boeoticum subsp. thaoudar); although a genetic separation exists. Both species are mostly two-grained and could potentially be the relatives of the extinct two-grained form. Pollen grains of several genetically well-identified wheat species, including T. urartu and T. boeoticum subsp. thaoudar, were studied by measuring grain diameters and examining the exine sculpturing throughout phase contrast microscopy and scanning electron microscopy, to gain insights into differences enabling taxonomic identification. This work showed that although T. urartu presents a smaller size on average, grain diameter is not enough due to size overlapping between species, and T. urartu presents a different exine sculpturing (scabrate) from other Triticum species (aerolate). This outcome is useful for taxonomists and archaeobotanists. Firstly, it will allow a simple re-classification of herbarium materials. Secondly, further research could establish whether T. urartu was cultivated.