Molecular cytogenetic identification and phenotypic description of a new synthetic amphiploid, Triticum timococcum (AtAtGGAmAm).

Abstract

A recently developed synthetic amphiploid, Triticum timococcum Kost., nom. nud. (2n = 6x = 42, AtAtGGAmAm) is described in the present study. This hexaploid taxon was developed by colchicine treatment in Martonvásár from the hybrid of a selected accession of Triticum timopheevii Zhuk. (2n = 4x = 28, AtAtGG) and a prebred semi-dwarf line of Triticum monococcum L. (2n = 2x = 14, AmAm). A detailed cytomolecular examination was carried out using the sequential multicolour fluorescence and genomic in situ hybridization techniques (FISH and mcGISH). It was proved that T. timococcum has 42 chromosomes originating from its parents. The chromosomes of the A genomes of T. monococcum and T. timopheevii could be distinguished in the amphiploid using FISH. The successful discrimination of the chromosomes was supported by the karyotypes of the three genomes and the successful optimization of the mcGISH technique for the A and G chromosomes achieved in the present study. A phenotypic evaluation was also carried out under natural and artificial growing conditions in 2012 and 2013. Based on the results, T. timococcum has intermediate characteristics in terms of spike (spikelet) shape and plant height, while it is similar to the female parent, T. timopheevii regarding pubescence. Like its parents, T. timococcum showed outstanding resistance to the main fungal diseases of wheat. T. timococcum headed later and developed longer and looser spikes, fewer tillers and only a third as many seeds than its parents. The third generation of T. timococcum was able to develop an acceptable number of seeds, even taking into account the reduced germination ability in the field.