Environmental and genetic factors affecting endosperm-based post-zygotic hybridization barriers

The endosperm, the nutrient reservoir in the seed, account for 70% of the human caloric intake worldwide. Understanding the genetic regulation of, and influences of external factors on endosperm development is important in adapting crop production to an increasingly changing environment. Endosperm development in many hybrid seeds is subject to parental conflict. Parental conflict can delay or trigger premature endosperm cellularization, resulting in a hybridization barrier. This can be caused by genomic imprinting – parent-of-origin specific gene expression. In this study, genetic- and molecular techniques, imaging, and genomic sequencing was utilized to analyze the effect of genetic and abiotic factors on the seed-based hybridization barrier. Crossing Arabidopsis thaliana with the sister-species A. arenosa or A. lyrata reveals a parental conflict leading to seed lethality, caused by delayed or premature endosperm cellularization, respectively. Different temperatures have contrasting effects on hybrid seed development, and single gene mutations significantly influence endosperm phenotypes. Using arctic species from the genus Draba, with no seed-based hybridization barriers, a unique parent-of-origin specific expression pattern was identified. In conclusion, mating systems, environmental conditions, and mutation of single genes significantly impact hybrid seed development, offering insights to predict and mitigate hybridization barriers for future crop improvement strategies.