Production and phenotypic characterization of nascent synthetic decaploids derived from interspecific crosses between a durum wheat cultivar and hexaploid Aegilops species

Wheat and its relatives include some allopolyploid species such as Aegilops juvenalis (Thell.) Eig (DDMMUU) and Aegilops vavilovii (Zhuk.) Chenn. (DDMMSS). Here, we successfully produced for the first time three allodecaploid lines with the AABBDDMMUU and AABBDDMMSS genomes through interspecific crosses between a tetraploid wheat cultivar and the two Aegilops species. Spike architecture of the synthetic lines showing a brittle rachis phenotype strongly resembled that of the parental hexaploid Aegilops species, but not that of the parental tetraploid wheat. Phenotypic differences of the spike and spikelet morphology were caused by one of the parental Aegilops species. Glumes of the synthetic decaploids were extremely hard, and all three synthetic lines had a soft texture with a smooth starch surface in endosperm cells. The soft-textured grains of the synthetic decaploids were due to accumulation of the puroindoline proteins derived from the genomes of parental allohexaploid Aegilops species. Therefore, the nascent synthetic decaploid lines highly reflect the phenotypic characteristics of the pollen parents. With further wheat breeding, the synthetic decaploids could have great potential to improve various traits.