MOLECULAR EVIDENCE FOR THE ORIGIN OF THE S‐DERIVED GENOMES OF POLYPLOID TRITICUM SPECIES

Abstract

The genus Triticum includes several polyploid species that arose due to hybridization between two or more diploid species. Section Sitopsis is comprised of five diploid species given the genome designation S. Four polyploid species are recognized that contain an S or S‐derived genome. We have used two repetitive DNA sequences found primarily in the S genomes of Triticum to determine the likely diploid progenitors of the polyploid species. Comparison of restriction fragments that hybridize to probes for these sequences suggests that T. speltoides is distinct from other members of section Sitopsis (i.e., T. longissimum, T. bicorne, T. searsii , and T. sharonense). The S‐derived genome of T. aestivum is more closely related to T. speltoides than to the other Sitopsis diploids. The restriction fragment pattern of T. timopheevii is 98% identical to that of T. speltoides , while those of T. kotschyi and T. syriacum are identical to the group of diploids represented by T. longissimum, T. bicorne, T. searsii , and T. sharonense. Our results are compatible with previous molecular and biochemical data regarding relationships among Triticum species containing an S or S‐derived genome.