Different effects of the cytoplasm on microsporogenesis have been observed in previous studies (LACADENA 1969; SANCHEZ-MONGE and SOLER 1973; LACADENA and PEREZ 1973; LARTER and HSAM 1973; SOLER 1975).

The cytoplasmic differences among the species used in this study have been reported by several authors in previous studies. Recently, CHEN et al. (1975) by means of electrophoretic analysis of the large subunit of the fraction 1 proteins of common wheats (with genetic information in chloroplasts DNA), have separated two distinct groups of species within the Triticinae with respect to their cytoplasmic constitution: (1) Ae. speltoides. T. dicoccum. T. aestivum and T. dicoccoides ; and (2) Ae. squarrosa, T. boeoticum, T. urartu and probably T. monoccum. Assuming cytoplasmic identity among Ae. squarrosa and Ae. ventricosa, and cytoplasmic differences of both species with respect to T. aestivum, cytoplasmically derived from Ae. speltoides, the effects of that cytoplasm on meiotic stability of common wheat corroborate cytoplasmic differences. However, on the basis of cytogenetic, morphological and fertility effects it can be assumed that the ventricosa cytoplasm is more similar to the cytoplasm of common wheats than the cytoplasms of T. timopheevi and Ae. caudata. It can be said that the timopheevi cytoplasm, that induces higher meiotic instability and male sterility than the ventricosa cytoplasm, is genetically different from the cytoplasms of the tetraploids and hexaploid wheats of today. CHEN et al. (1975) suggest that in the origin of tetraploid wheats, the B-genome donor was also the source of the cytoplasm. Similary, the B'-genome donor of T. timopheevi must have been the maternal parent in the cross with T. monococcum The contributing species of the B and B' genomes must consequently differ both genetically and cytoplasmically.

There is no difierence between the effects of the nuclear genes of the two Spanish cultivars used in this work with respect to the meiotic stability and male-fertility-restoring genes.

The data presented here show that ventricosa cytoplasm seems to have less intense effects on meiotic stability, development of anthers and male-fertility. The caudata cytoplasm induces meiotic instability and produces pistilloid stamens, malformation of anthers and male-sterility. The timopheevi cytoplasm induces male-sterility and a lesser level of meiotic instability, being for this reason more useful in programs of utilization of male-sterility in the improvement of wheat.

Literature Cited

CHEN, K., J.C.: GRAY and S.G. WILDMAN 1975. Fraction 1 protein and the origin of polploid wheats. science, 190: 1304-1306.

FUKASAWA, H. 1953. Studies on restoration and substitution of nucleus in Aegilotricum. I. Appearance of male-sterile durum in substitution crosses. Cytologia 18: 167-175.

KIHARA, H. 1951. Substitution of nucleus and its effects on genome manifestations. Cytologia 16: 177-193.

LACADENA, J.R. 1969. Microsporogenesis in alloplasmic rye. Wheat Inf. Serv. 29: 21-22.

LACADENA, J.R. and M. PEREZ 1973. Cytogenetical analysis of the interaction between Triticum durum cytoplasm and Secale cereale nucleus at the diploid and tetraploid nuclear levels. Proc. 4th. Int. Wheat Genet. Symp.: 355-360.

LARTER, E.N. and S.L.K. HSAM 1973. Performance of hexaploid Triticale as influenced by source of wheat cytoplasm. Proc. 4th. Int. Wheat Genet. Symp.: 245-251.

MAAN, S.S. 1975. Cytoplasmic variability in Triticinae. Wheat Inf. Serv., 40: 1-6.

SANCHEZ-MONGE, E. and M.C. SOLER 1973. Wheat and Triticale with rye cytoplasm. Proc. 4th Int. Wheat Genet. Symp. : 387-390.

SOLER, C. 1975. Estudio comparativo de un alohexaploide artificial, Triticum x Secale (Triticale) sobre los citoplasmas de las especies parentales. An. I.N.I.A. Ser. Prod. Veg. 5: 9-82.