Pre- and post-fertilization to backcrossing in interspecific hybridization between F. esculentum and F. homotropicum with F. esculentum

Woo, S.H¹., T. Ohmoto², C. Campbell³, T. Adachi² and S.K. Jong⁴.

¹ Yokohama City University, Kihara Inst. Biol. Res., Maioka 641-12, Totsuka, Yokohama 244-0813, Japan. ² Laboratory of Plant Genes and Physiology, College of Agriculture, Osaka Prefecture University, Gakuencho 1-1, Sakai, Osaka, 599-8531, Japan ³ Kade Research Ltd., Morden, Manitoba, Canada R6M 1E9 ⁴ Dept. of Agronomy, College of Agriculture, Chungbuk National University, Chongju 361-763, Korea.

Woo, S.H., T. Ohmoto, C. Campbell, T. Adachi and S.K. Jong. 2001. Pre- and Post-Fertilization to backcrossing in interspecific hybridization between F. esculentum and F. homotropicum with F. esculentum. Eighth International Symposium on Buckwheat, Chunchon, Korea, Kangwon University Press. pp. 450-455

Abstract: To facilitate the introgression of F. esculentum into the traits of F. homotropicum, several accessions of the hybrids between these two species were pollinated with F .esculentum as the recurrent parent. An in vitro embryo rescue was performed to increase the recovery of backcross progenies. The F₂ generation was more amenable than the F₁ hybrids to produce backcross progenies. The F₁ hybrids were backcrossed twice with common buckwheat (pin-type F. esculentum) (recurrent backcrossing). Also, alternate backcrossing with common buckwheat and F. homotropicum (congruity backcrossing) were carried out. Pollen tube growth of the BC F₁ F. esculentum (thrum) and F. homotropicum x BC F₁ was a disturbed penetration exceeded for all initial interspecific hybrids, and its requirement was proportionately lower when the common buckwheat was used as the recurrent parent and as the last parent in congruity hybrids. Effects of both common buckwheat and F. homotropicum on seed success rate for hybridization were observed. Growth of hybrid embryos before rescue, regeneration of mature hybrids all increased recurrent and congruity backcrosses and intercrosses between F₁ plants and selected fertile plants of the second congruity backcrosses.

Key words: Fagopyrum esculentum Moench., F. homotropicum Ohnishi, interspecific backcrosses, incompatibility, pollen tube growth, embryo development, embryo rescue, heterostyly, seed set