Endosperm-derived hybridization barrier in intergeneric hybrid between Brassica rapa and Raphanus sativus

Interspecific or intergeneric hybridization is vital to the evolution of flowering plants. However, interspecific or intergeneric hybridization often faces in hybridization barriers, resulting in seed abortion or sterility of F1 hybrids. In angiosperms, failure of endosperm development is one of the major causes of immediate hybridization barrier. To date, dysregulation of imprinted genes in developing endosperm has been proposed to be explain the endosperm-derived hybridization barrier. A general mechanism of hybridization barrier remains to be demonstrated. xBrassicoraphanus is an intergeneric hybrid of Chinese cabbage (Brassica rapa L.) and radish (Raphanus sativus L.). Newly synthesized xBrassicoraphanus F1 hybrids often display seed abortion accompanied with embryo arrest and underdeveloped endosperm. Here I report that intergeneric F1 hybrid between B. rapa and R. sativus showed endosperm-derived hybridization barrier. RNA-seq was conducted on