Format: ORAL

Sarah B. Carey1

1 HudsonAlpha Institute for Biotechnology

The Cannabaceae family has a deep history regarding their dioecious flowers and sex chromosomes. One century ago, the XY pair that controls the development of the sexes was identified in the hop Humulus lupulus var. lupulus, owing to the cytologically smaller Y chromosome relative to the X. Curiously, examinations across other species in Humulus and in the sister genera Cannabis uncovered varying cytological differences. In Cannabis, the Y chromosome is bigger than the X, while other varieties of Humulus remain homomorphic or have evolved a multiple sex chromosome system (e.g., XXYY). Despite these early discoveries, we know little about the Cannabaceae sex chromosomes at the molecular level. This is largely due to the complexities of assembling XY pairs in genome references. Here we use a combination of Illumina, PacBio HiFi, and Dovetail Omni-C data to assemble fully-phased genomes for XY males of Cannabis and Humulus. Using these assemblies, we first show that the XY pairs match the known cytology. We next use these assemblies to explore the dynamic patterns of gene gain and loss, as well as structural changes that have shaped the XY pairs. Ultimately these comparative analyses across Cannabaceae will uncover genes that control the development of the economically valuable females of hop and hemp.