Abnormal development observed in the hybrid endosperm between cultivated and wild rice

Abstract

Abnormal endosperm development is observed in inter-specific or inter-ploidy crosses of many plant species. Several reports suggested that the endosperm failure is caused either by promotion or suppression of the endosperm development and this can be due to the functional difference between parental genomes. One of the possible molecular mechanisms underlying this phenomenon can be genomic imprinting, an epigenetic mechanism with parent-of-origin dependent mono-allelic gene expression.
We conducted inter-specific crosses between several cultivated and wild rice species and found abnormality in hybrid endosperm. In these crosses, the rate of nuclear division of the endosperm was not affected but the timing of cellularization was found to be delayed or advanced. We also carried out the microarray analysis using hybrid endosperm of O. sativa and O. longistaminata, and identified the candidate genes related to the endosperm failure. Possible involvement of these genes and their effects on the endosperm development will be discussed.