Self-sterility in Nicotiana

 

Self-sterility in Nicotiana In plants, multiple alleles have been reported in association with self-sterility or self incompatibility. 

Self-sterility means that the pollen from a plant is unable to germinate on its own stigma and will not be able to bring about fertilization in the ovules of the same plant. 


East (1925) observed multiple alleles in Nicotiana which are responsible for self-incompatibility or self-sterility. 

The gene for self-incompatibility can be designated as S, which has allelic series S, S, S, S and S

The cross-fertilizing tobacco plants were not always homozygous as SS or SS, but all plants were heterozygous as SS, SS, S₅,S

When crosses were made between different SS plants, the pollen tube did not develop normally. 

But effective pollen tube development was observed when crossing was made with other than SS for example SS


When crosses were made between seed parents with SS and pollen parents with SS, two kinds of pollen tubes were distinguished. 

Pollen grains carrying S were not effective, but the pollen grains carrying S were capable of fertilization. Thus, from the cross SSXSS, all the pollens were effective and four kinds of progeny resulted: SS, SS, SS and SS.

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