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Wheat Information Service
Number 83: 7-14 (1996)


Spontaneous translocations in Triticum araraticum Jakubz.

T. Kawahara1, E.D. Badaeva2, N.S. Badaev3 and B.S. Gill2

1Plant Germ-plasm Institute, Faculty of Agriculture, Kyoto University, Mozume, Muko 617, Japan
2Wheat Genetics Resource Center, Department of Plant Pathology, Kansas State University, Throckmorton Hall, Manhattan, KS 88506 5502, USA
3Centre of Bioengineering, Russian Academy of Sciences, Vavilov Str.34/5, Moscow 117334, Russia


Summary

Spontaneous reciprocal translocations were identified in Triticum araraticum Jakubz. by crossing experiments. Seventy nine strains had the standard chromosome arrangements without translocation. Twenty one strains were classified into 14 chromosome types based on these translocations but 35 strains remained unidentified. Furthermore, karyotypes were analyzed by C-banding on 17 strains representing all the chromosome types. Of 18 translocations, 12 were between G genome chromosomes, five were between the G and At genome and one was between At genome chromosomes. Within the G genome, 4G and 6G had higher frequencies of their involvement in translocations than the others. The present study revealed the wide structural variation of chromosomes and the high frequency of breakpoints on the G genome in T. araraticum.

Key words: Triticum araraticum, reciprocal translocation, translocation breakpoint, C-banding


Introduction

Triticum araraticum Jakubz. is a wild tetraploid wheat belonging to the Timopheevi group with AtAtGG genome (2n=4x=28). It grows in Eastern Turkey, Northern Iraq, Western Iran and in Transcaucasus, Armenia, Azerbaijan and Nachichevan. It differs cytogenetically from another wild tetraploid wheat, T. dicoccoides Korn. with AABB genome. Hybrids of the two species can be easily obtained but they are completely male sterile due to abnormal meiosis. T. araraticum is highly polymorphic in morphological characters, resistance to disease and DNA amounts (Tanaka and Sakamoto 1979, Saito and Ishida 1979, Nishikawa et al. 1979, 1988). Thus, it has a high potential as a gene resource for breeding of cultivated wheats.

Analysis of chromosome pairing at meiosis of intraspecific hybrids, as well as karyotype analysis by C-banding, showed that chromosomal rearrangements played an important role in the formation of intraspecific diversity of T. araraticum (Kawahara and Tanaka 1977, 1983, Badaeva et al. 1990). Badaeva et al. (1994) observed karyotypes of 185 accessions by C-banding and described chromosomal divergence in this species. However, several translocations reported earlier could not be detected by C-banding alone due to an insufficient number of marker bands on the At genome chromosomes. To clarify the whole pattern of chromosomal rearrangements we synthesized the data obtained from chromosome pairing and C-banding.

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