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.
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.
- Chennaveeraiah M (1960) Karyomorphologic and cytotaxonomic studies in Aegilops. Acta Hort Gothoburg 23:85–178Google Scholar
- Cifuentes M (2007) Intergenomic pairing and formation of unreduced polen in wheat × Aegilops hybrids. Technical University of Madrid. http://oa.upm.es/1811/1/MARTA_CIFUENTES_OCHOA.pdf
- Dvorak J (1998) Genome analysis in the Triticum-Aegilops alliance. In: Proceedings of the 9th international wheat genetics symposium. Saskatoon, pp 8–11Google Scholar
- Hammer K, Morimoto Y (2011) Classifications of infraspecific variation in crop plants. In: Guarino L, Ramanatha RV, Goldberg E (eds) Collecting plant genetic diversity: technical guidelines, 2011 Update. http://cropgenebank.sgrp.cgiar.org/index.php?option=com_content&view=article&id=665
- Kihara H (1963) Interspecific relationship in Triticum and Aegilops. Seiken Ziho 15:1–12Google Scholar
- Kimber G, Feldman M (1987) Wild wheat. An introduction. Special Report 353, College of Agriculture, University of Missouri-ColumbiaGoogle Scholar
- Maxted N (2011) Aids to taxonomic identification In: Guarino L, Ramanatha RV, Goldberg E (eds) Collecting plant genetic diversity: technical guidelines. 2011 Update. http://cropgenebank.sgrp.cgiar.org/index.php?option=com_content&view=article&id=390&Itemid=557
- van Slageren MW (1994) Wild wheats: a monograph of Aegilops L. and Amblyopyrum (Jaub. & Spach) Eig (Poaceae). Wageningen Agricultural University Papers, vol 94–7. Agricultural University, WageningenGoogle Scholar
- Witcombe JR (1983) A guide to the species of Aegilops L.: their taxonomy, morphology and distribution. International Board for Plant Genetic Resources (IPGRI), RomeGoogle Scholar