The importance of Arabidopsis seed mutants in the elucidation of the molecular basis of Endosperm Balance Number in tuber-bearing Solanum species.

The Endosperm Balance Number (EBN) is an important concept for potato breeding and has evolutionary importance in tuber-bearing Solanum species. The EBN is part of the post-zygotic hybridization barriers in the group and represents a reproductive isolating mechanism. Few genes have been proposed to be involved in its genetic control; until now, however, neither specific genes nor its molecular basis have been well established. Histological observations of embryo and endosperm development in inter-EBN crosses in tuber-bearing Solanum revealed phenotypes similar to those recently described in Arabidopsis seed mutants. The common feature between them is that the endosperm nuclei become greatly enlarged and that embryos are arrested at the globular stage. The proteins encoded by the Arabidopsis TITAN genes are related to chromosome dynamics and cell division. Based on the sequence of titan mutants, genes in potato species related to cell cycle and microtubule assembly were isolated. In this article a perspective model is proposed to explore the utility of Arabidopsis mutants associated with cell cycle control as a tool to elucidate the molecular basis of EBN in potato. Further research focused on the expression pattern of these genes in intra- and inter-EBN crosses in potato species will be performed.