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Based on the average taxonomic distances estimated by the respiratory electron flows under both normal and NaCl salinity conditions, a dendrogram showing the phylogenetic relationships was constructed. In this dendrogram, B plasm type of CS was clustered with Mu, G, S, Sl and Mt plasm types (Fig. 2). Among these five plasm types, Mu, G and S showed higher total activities than CS under the normal condition and higher alternative path activities under the salinity condition and Mt plasm type showed higher total and alternative path activities under the salinity condition. Only Sl plasm type showed the respiratory activity equivalent to that of CS under both conditions. The results suggested that Sl-palsm type of Ae. sharonensis is most closely related to B palsm of CS.

A large volume of research results have been accumulated on the interspecific variations in the nuclear and organellar DNAs of Triticum and Aegilops species, suggesting that Ae. speltoides is the cytoplasm donor of polypIoid wheat (Tsunewaki et al. 1976; Breiman 1987; Ogihara and Tsunewaki 1988; Dvorak and Zhang 1990; Terachi and Tsunewaki 1992; Miyashita et al. 1994; Tsunewaki 1995; Ohsako et al. 1996; Wang et al. 1997). However, there are several reports suggesting that Ae. sharonensis, Ae. searsii and/or Ae. longissima are the cytoplasm donor(s) of B plasm type (Sears 1956; Feldman 1978; Kushnir and Halloran 1981, 1982; Nishikawa and Furuta 1978; Nath et al. 1983, 1984). Although some major discrepancy can be seen between the phylogenetic relationships,constructed based on the respiratory electron flows (Fig. 2) and those based on various agronomic characteristics and organellar DNA polymorphisms (for a review see Tsunewaki 1995), our results pointed out the possibility that Ae. sharonensis might have played a role in the evolution of B palsm type of polypIoid wheat.


Acknowledgments

This work was supported in part by Grant-in-Aid for JSPS Fellow to KK. The authors would like to express sincere thanks to Prof. K. Tsunewaki, Fukui Prefectural University, for providing us with the original alloplasmic hybrids. Contribution No. 107 from the Laboratory of Plant Genetics, Faculty of Agriculture, Kobe University.


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