Overcoming the barrier to interspecific hybridization of Fagopyrum esculentum with Fagopyrum tataricum

Abstract

Tartary buckwheat (Fagopyrum tataricum) was successfully hybridized with common buckwheat (F esculentum), both diploid (2n = 16), using the latter as male parent during bud pollination . The barrier normally encountered in such hybridization was overcome by enhancing the cross-compatibility of the two species, which was accomplished by synthesizing a unique genotype of common buckwheat . This novel plant was produced by selecting common buckwheat plants that exhibited, at isozyme loci PGM, SKDH and ADH, alleles with similar mobility to those found in tartary and then transferring these alleles to a single plant through six generations of breeding . Ovule culture was used to rescue the 7-10 day old embryos . On the rescue-culture medium 41% of the hybrid embryos formed calli larger than 200 pm in diameter. Most ceased to grow before reaching 1500 µm, but four out of 263 cultured ovules continued to grow as callus . One of these differentiated and formed callus with buds and shoots from which cloned plants were produced . The remaining embryos either did not grow at all or formed very small calli . When tartary was crossed with the original genotype of common buckwheat, only 22% of the hybrid embryos formed small calli and none differentiated . Hybridity of the calli and the plantlets was determined by RAPD and isozyme analysis, respectively . Flowers produced by the hybrid plants were of the same type (homomorphic) and size as those of tartary, but with white sepals like common buckwheat .

Inheritance of self-compatibility and flower morphology in an inter-specific buckwheat hybrid

“…However, the plantlets regenerated from these embryoids were spindly, rootless and albino. Samimy et al (1996) reported the development of a hybrid through embryo rescue in a cross between F. esculentum and F. tataricum. We were successful in developing hybrids between common buckwheat and F. homotropicum.…”

“…Recently, Samimy et al (1996) and Wagatsuma and Un-no (1995) have exploited possibilities for ovule culture. In our ovule culture experiments, more than 18% of the excised ovules germinated after 30-35 d in vitro, but only 25.6% of the germinated ovules regenerated into transplantable seedlings (Table 1, Fig.…”

“…Krotov and Dranenko (1975) produced a new species F. giganteum from the hybrid between tetraploid F.tataricum and F. cymosum. Samimy (1991) and Samimy et al (1996) developed an infertile plant from the cross of diploid F. esculentum and F. tataricum. Wagatsuma and Un-no (1995) reported on the first fertile cross of diploid F. esculentum and F. tataricum.…”

Failure of Fertilization Associated with Absence of Zygote Development in the Interspecific Cross of Fagopyrum tataricum * F.esculentum.

“…In general, it is difficult to obtain interspecific hybrids in buckwheat through conventional techniques due to the presence of strong pre-and post-fertilization barriers. Samimy et al (1996) developed an infertile plant. Wagatsuma and Un-no (1995) reported the first fertile hybrid from the cross of the diploid F. esculentum and F. tataricum.…”

Interspecific hybridization between diploid Fagopyrum esculentum and tetraploid F. homotropicum

“…Efforts to improve common buckwheat have been made through interspecific hybridization between common buckwheat and related species F. cymosum (Ujihara et al 1990;Suvorova et al 1994;Hirose et al 1995;Rumyantseva et al 1995;Woo et al 1999a) and F. tataricum (Morris 1951;Samimy 1991;Hirose et al 1995;Samimy et al 1996;Chen 1998;Wang and Campbell 1998;Woo 1998;Fesenko et al 2001;Wang et al 2002a). However, success has been limited due to sterility of the hybrids.…”