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We analysed nine traits of the root system of 223 genotypes of Triticum turgidum (2n = 4x = AABB) subspecies dicoccoides, dicoccum, turgidum, durum and polonicum, finding a large intra and interspecific variability in both the number and size of roots, as well as in their spatial distribution. We studied the presence of an incomplete MITE (Miniature Inverted-repeat Transposable Element) inserted in the TtDro1B gene, which is present in some genotypes of dicoccoides, dicoccum, and turgidum, but not in polonicum and the 97.9% of the durum accessions. Comparison between genotypes shows that genotypes with the MITE element have smaller and shallower roots. Since Aegilops is considered to be the donor of the wheat B genome, the presence of the same MITE element was analysed in 55 accessions of the species Aegilops speltoides, searsii, bicornis and longissima, and in no case was it detected. We propose that after the emergence of T. turgidum subsp. dicoccoides, the insertion of the MITE element probably occurred in a single plant. Subsequent domestication resulted in genotypes of dicoccum with and without the MITE element, which after selection gave rise to the subspecies turgidum, and durum and polonicum, respectively. The MITE element can be used to differentiate turgidum from the durum and polonicum with high reliability. |
