XVI International Botanical Congess

It has been suggested that Efs are the genetic loci in maize responsible for the 2 maternal:1 paternal genomic ratio required for normal endosperm development. A paternally transmitted deficiency for an Ef results in a small kernel and cannot be rescued by extra maternally derived copies. We have been using various dosage series generated with B-10L translocations to determine how Efs may act to affect endosperm development. We have identified genes that show altered expression in relation to Ef dosage, suggesting that Efs are involved in regulating endosperm gene expression. The small kernel phenotype conditioned by Ef aneuploidy could result from an imbalance in regulatory factor dosage. Our lab has also undertaken the generation of a compound translocation, carrying a combination of the four major Ef regions, to test the role of Efs in the failure of endosperm in interploidy crosses.