Development and validation of chloroplast DNA markers to assist Aegilops geniculata and Aegilops neglecta germplasm management
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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.
KeywordsAegilops Chloroplast DNA markers Crop wild relatives Genetic resources management
This work has been funded by Grant RF2011-00018 from National Institute for Agricultural and Food Research and Technology and FEDER funds. The authors wish to thank their contribution to all collector institutions (Centro La Orden-Valdesequera in Badajoz and Institute of Research and Training in Agriculture and Fisheries in Córdoba) and Genebanks (National Plant Genetic Resources Centre in Spain, Centre for Agricultural Research of the Hungarian Academy of Sciences in Martonvasar, National Small Grains Collection of the United States Department of Agriculture and the Leibniz Institute of Plant Genetics and Crop Plant Research in Gatersleben) that provided the materials analysed in the study, and R. Fite, M. J. Tomás, S. Cárcamo, X-Q. Zhou, and L. Stolzenburg for technical assistance.
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