Abstract only

Genetic analysis and application of tester varieties contribute to disclose the nature of hybrid necrosis, red chlorosis, yellow chlorosis and stunt. Comprehensive study of intra- and inter- species hybrids produced through intraspecific crosses of aboriginal varieties of winter bread wheat population, with the endemic Georgian and other wheat species, has shown the frequent occurrence of genetic phenomenon of full or partial lethality in hybrids, beginning from the first hybrid generation. From 759 breeding combinations we have studied, only 102 appeared to be completely vital, 520 occurred to be sub-lethal and 137 were totally lethal. Reason of the total or partial lethality in certain interspecific hybrid combinations was not a phylogenetic remoteness of initial parental forms, but hybrid necrosis, red hybrid chlorosis, yellow hybrid chlorosis or hybrid stunt caused by the combined effect of two dominant complementary genes Nel andNe2 (Nel+Ne2 genetic system), as well as genes Chl and Ch2 (Chl + Ch2 genetic system), or DI and D2D3 (Dl+D2D3 genetic system). Sub-Iethal hybrids were produced in cases when parental forms carried weak alleles of necrosis, yellow chlorosis, red chlorosis and stunt genes, and the lethal ones when one parental form carried strong allele of necrosis, chlorosis and stunt gene while the other parental form at least its moderate gene. Phenomena of hybrid necrosis, red hybrid necrosis, yellow hybrid necrosis as well as hybrid stunt were not observed in populations produced through crosses of tetraploid wheats (T durum, T turgidum, T carthlicum, T polonicum, T georgicum, T dicoccum, T dicoccoides) with winter bread wheat of Kartli ecotype (Dolis Puri 35-4, Dolis Puri 18-46, Kartlis TetriDolis Puri, Kartlis Tsiteli Dolis Puri), as well as with species of hexaploid wheats T compactum and T Zhukovski. Populations produced through crossing ofthe same tetraploid (T durum, T turgidum, T carthlicum, T plonicum, T dicoccum, T georgicum) and hexaploid (T macha, T compactum) species with spring and winter varieties of West Georgian ecotype (Tetri Ipkli, Tsiteli Ipkli, Korboulis Dolis Puri and Khulugo ), mountainous Meskheti ecotype (Akhaltsikhis Dolis Puri) as well as breeder (Bezostaya 1, Spartanka, Motsinave, Taragi, Megobroba 2, Tbilisuri 1, Mukhranula 1, Tbilisuri 8, Tbilisuri 12) and also with hybrid combinations derived from interspecific hybridization oftetraploid wheats with Tdiococcoides, occurred to be semi- lethal. Totally lethal were hybrid combinations produced through crosses of the same tetraploid varieties with species of winter bread wheat of Kakheti ecotype (Kakhuri Dolis Puri, Kakhi 8, Lagodekhis Grdzeltavtava), as well as through hybridization ofbread wheat with T timopheevi and T diococcoides va1:arabicum, which carries gene Chl. Studies proved that genes of necrosis, red chlorosis, yellow chlorosis and hybrid stunt may occur concurrently in some genotypes, with genes of chlorosis having an epistatic effect on genes of necrosls. Investigation of location of genes determining necrosis, red hybrid chlorosis, yellow chlorosis and hybrid stunt in wheat has enabled to outline the geographic pattern of distribution of these genes on the territory of Georgia.

English

0409|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection