Abstract:
For ages, plant breeders have relied on the genetic variability that results from sexually crossing
plants within the same species. However, the variability that exists within species populations is
inadequate, hence the need to exploit desirable traits of interest in distantly related or even
unrelated plants through hybridization techniques. Hybridization can be categorized into two; sexual
and somatic. Sexual hybridization, also referred to as wide or distant hybridization involves
combining two genomes from different parental taxa through pollination, either naturally or by
induction. Somatic hybridization involves the fusion of somatic cells instead of gametes, which
highly depends on the ability to obtain viable protoplasts and eventually differentiate them to whole
plants in vitro. The impacts of hybrids can either be positive or negative. Among the positive
attributes of hybrids that have been exploited is heterosis, which results either from dominance,
over-dominance or epistasis. Negative ones include sterility, arrested growth of the pollen tube and embryo abortion. To overcome these problems, chromosome doubling, the use of hormones such
as 2, 4-Dichlorophenoxyacetic acid (2, 4-D) and embryo rescue have been employed to overcome
sterility, arrested growth of pollen tubes and embryo abortion respectively. After the development of
hybrids, different hybrid identification techniques have been used to test them such as the use of
molecular and morphological markers, cytogenetic analysis and fluorescent in situ hybridization.
The use of hybridization techniques in plant improvement remains a vital tool to cross species
barriers and utilization of important attributes in unrelated crop plants which could not have been
achieved through conventional techniques of plant breeding.
