Discarding of the postzygotic reproductive barrier between hexaploid wheat (Triticum aestivum L.) and rye (Secale cereale L.).

Autor: Tikhenko, Natalia, Rutten, Twan, Senula, Angelika, Rubtsova, Myroslava, Keller, E. R. Joachim, Börner, Andreas
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Zdroj: Cereal Research Communications; 2017 Supplement S1, Vol. 45, p8-9, 2p
Abstrakt: Postzygotic reproductive isolation in response to hybridization of plants is a major factor limiting production of the hybrids in breeding programs. This mechanism is manifested in the different stages of the ontogenesis of distant hybrids. In crosses between hexaploid wheat Chinese Spring and certain rye inbred lines abortion of shoot apical meristem (SAM) during the differentiation of the hybrid embryo leads to embryo lethality. Such kind of embryo lethality is the result of a negative complementary interaction between wheat and rye loci. These loci were named Eml-R1 and Eml-A1. Eml-R1 locus has two alleles which are either compatible (Eml-R1a) or incompatible (Eml-R1b) with the wheat genome. The postzygotic barrier that results from an interaction between incompatible wheat Eml-A1 and rye Eml-R1b alleles can be easily overcome by the application of auxinic herbicide 2,4-D to tissue cultures of abnormal embryos at 14−16 days after pollination. Callus cultures of abnormal embryos show a high regenerative capacity, even without the application of exogenous cytokinin. This characteristic indicates that the reproductive barrier between hexaploid wheat and certain rye inbred lines may be mediated by epigenetics. After colchicine treatment during callus culture, amphidiploid plants were obtained. However, most of these plants did not produce seeds, due mainly to sterility of the pollen but also of the embryo sacs. These findings demonstrate that hybrid sterility affects both male and female gametophytes in plants obtained from abnormal embryos. The key roles of double fertilization and stress factors in the implementation of the apical meristem formation programme in embryos from incompatible intergeneric crosses between hexaploid wheat and rye during in vitro culture are discussed. We also propose a hypothetical model for a wheat-rye lethality system involving differential expression of incompatible wheat Eml-A1 and rye Eml-R1b alleles in an identical genetic background. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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