Development and validation of chloroplast DNA markers to assist Aegilops geniculata and Aegilops neglecta germplasm management

The genus Aegilops includes a number of wheat wild relatives representing a valuable gene pool for stress adaptive traits. Collection of new accessions and proper management of Aegilops germplasm is thus essential for wheat improvement progress. Among the most worldwide distributed Aegilops species, A. geniculata Roth (2n = 4x = 28), A. neglecta Req. ex Bertol. (subsp. neglecta; 2n = 4x = 28) and A. recta (Zhuk.) Chen. (syn. A. neglecta Req. ex Bertol. subsp. recta (Zhuk.) Hammer; 2n = 6x = 42) are particularly difficult to distinguish each other because of their high morphological and genomic similarities. Based on their distinct cytoplasmic lineage, we have developed two chloroplast DNA-based molecular markers that accurately discriminate A. geniculata from A. neglecta and A. recta. The use of these markers, aided by chromosome counting to differentiate A. neglecta from A. recta, has allowed to assess the accuracy of species assignment in 125 accessions from Germplasm Genebank collections and recent collecting expeditions. This study has revealed taxonomic mistakes or inaccuracies in 18 % of the entries examined. The ambiguous use of the same species name for the allotetraploid A. neglecta and the allohexaploid A. recta, very extended among germplasm banks and managers, is in the origin of some of the errors detected.