Unilateral Incompatibility

Abstract

Successful hybridization of crop plants with their related distant species and genera is a prerequisite for transfer of useful traits from the latter. There have been numerous attempts in which interspecific and intergeneric crosses have been successful in only one direction while the reciprocal cross fails (Table 3.1). The phenomenon has been variously described as unilateral incompatibility (UI), interspecific incompatibility, unilateral hybridization, unilateral inhibition, unidirectional crossability, and one-way isolation etc. (Abdalla and Hermsen 1972). Although unilateral incompatibility occurs, in general, exclusively in inter-specific crosses, all interspecific crosses do not exhibit unilateral incompatibility. In the opinion of the author, the term unilateral incompatibility, in comparison and contrast to self-incompatibility, should include various processes and barriers leading to the success or failure of interspecific crosses in one direction from the time of successful pollination up to hybrid zygote formation. Other presyngamic and post-syngamic barriers to interspecific hybridization and hybrid sterility restricting gene flow across species have been dealt with in Chapter 2 of the present Volume.KeywordsPollen TubePollen Tube GrowthReciprocal CrossIncompatible PollenPollen Tube LengthThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.