Chapter

Genetic Dissection of Sexual Reproduction in Rice ( Oryza sativa L.)

12/2007; DOI:10.1007/978-3-540-74250-0_15 pp.191-204

ABSTRACT Sexual reproduction is the most important step in increasing the genetic diversity of offspring. It is defined by two major
events: meiosis and fertilization. Meiosis is a crucial event to form haploid spores and gametes, and is characterized by
a single round of premeiotic DNA replication followed by two continuous rounds of chromosome segregation. Homologous recombination,
an essential feature of meiosis, results in generating new haplotypes by shuffling alleles. Fertilization is achieved by the
fusion of two gametes and produces new genotypes of diploid cell or zygote. In contrast, reproductive isolation contributes
to establishing genetic stability of species, rather than genetic diversity, in most eukaryotes, and is achieved by various
mechanisms, for example, the differential fitness of the gametophyte or zygote (Dobzhansky 1951; Stebbins 1958). Biological
species are generally defined as groups of interbreeding populations that are reproductively isolated (Mayr 1942).

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Keywords

chromosome segregation
 
continuous rounds
 
differential fitness
 
diploid cell
 
essential feature
 
form haploid spores
 
gametes
 
genetic diversity
 
interbreeding populations
 
new genotypes
 
new haplotypes
 
premeiotic DNA replication
 
reproductive isolation contributes
 
reproductively
 
Sexual reproduction
 
zygote
 

Ken-Ichi Nonomura