Breeding of Fruit and Plantation Crops

Gametophytic and Sporophytic self incompatibility

Gametophytic self incompatibility

• In this type of incompatibility, pollen is binucleate and pollen behaviour is determined by the S allele present in each pollen and stigma is wet type.
• It means the incompatibility reaction of pollen is determined by its own genotypes, and not by the genotype of the plant on which it is produced.
• Generally, incompatibility reaction is determined by a single gene having multiple alleles. Sometimes, polyploidy may lead to the loss of incompatibility due to a competition between the two S alleles present in diploid pollen.
• Important examples are pineapple, loquat, apple, pear, plum, cherry, almond, apricot, some citrus and members of Solanaceae family.

Sporophytic incompatibility

• The incompatibility reaction of pollen is governed by the genotype of plant on which the pollen is produced and not by the genotype of the pollen.
• It means the incompatibility is imposed by the maternal genotype, due to that all the pollen grains from a given plant behave similarly.
• Incompatibility occurs at the stigmatic surface resulting in the inhibition of pollen germination. Pollens are trinucleate and the stigmatic surface is dry e.g. Mangifera indica.