The crossing of common wheat (Triticum aestivum L.) with cultivated rye (Secale cereale L.). I. crossability, pollen grain germination and pollen tube growth

Abstract

The crossing of common wheat (Triticum aestivum L.) with rye (Secale cereale L.), and especially the action of the crossability genes of wheat, was studied using the readily crossable wheat cv Chinese Spring (genotype kr 1 kr 1 kr 2 kr 2 >), the poorly crossable wheat cv Hope (genotype Kr 1 Kr 1 Kr 2 Kr 2 ), as well as the disomic substitution line of chromosome 5B of Hope into Chinese Spring (CS/Hope 5B, genotype Kr 1 Kr 1 kr 2 kr 2 ). By comparing crossability and actual fertilization, the poor crossability with rye of both cv Hope and the CS/Hope 5B substitution line was shown to result from absence of fertilization. Studies of pollen grain germination and pollen tube growth showed that the dominant alleles of the crossability genes manifested themselves through retardation and eventually inhibition of pollen tube growth at the style base and in the ovary wall. In Hope the growth of all pollen tubes was inhibited, whereas in CS/Hope 5B rarely fertilization was achieved. The recessive alleles of the crossability genes do not seem to have an influence on the growth of rye pollen tubes in wheat pistils.