UGA plant biologist leads new advances in biotech

The evolutionary lineage leading to Amborella diverged from all other flowering plant lineages approximately 150 million years ago. In 2013, an international research team co-led by UGA Plant Biology faculty member Jim Leebens-Mack and collaborators announced the newly sequenced genome of the Amborella trichopoda plant became the foundation for comparative analyses of genes tracing back to the origin of flowering plants and earlier. 

A new publication analyzes a much-improved genome assembly and annotation to characterize and investigate the Z and W sex chromosomes and the genes responsible for sex determination. Unlike the humans and plants like asparagus with males having X and Y sex chromosomes, Amborella females have distinct Z and W sex chromosomes as is the case for birds and buterflies. Detailed characterization of Amborella's sex determination system sheds new light on the mechanisms that determine plant reproduction in crop species and more generally, the mechanisms that determine plant reproduction crucial for modern agriculture:

A groundbreaking study published in Nature Plants has shed new light on the complicated reproductive strategies of flowering plants. The study, led by researchers at the HudsonAlpha Institute for Biotechnology and the University of Georgia, delved into the genetics of Amborella trichopoda, a species of flowering plants that offers a unique window into the early evolution of flowering plants. With their much-improved assembly of the Amborella genome and sex chromosomes, the researchers have gained valuable insights into the evolution of flowering plants and their reproductive strategies.

Amborella trichopoda is the sole surviving species of a lineage that diverged from all other flowering plants early in their evolutionary history. Its genome provides invaluable insights into the genetic underpinnings of plant diversity.

Eleven years ago, an international team of researchers co-led by Jim Leebens-Mack, PhD, professor of plant biology at the University of Georgia , completed the first Amborella genome. The seminal study, the results of which were published in Science in 2013, has been cited more than 575 times over the last eleven years.

“The evolutionary lineage leading to Amborella diverged from all other flowering plant lineages approximately 150 million years ago, so our draft genome published in 2013 has been a foundation for comparative analyses of genes tracing back to the origin of flowering plants and earlier,” says Leebens-Mack. 

The new insights gained from the improved genome assembly are especially exciting for HudsonAlpha Faculty Investigator Alex Harkess, PhD, who was a PhD student in Leebens-Mack’s lab working on the Amborella genome. Now the leader of his own lab at HudsonAlpha, Harkess and one of his mentees, HudsonAlpha Senior Scientist Sarah Carey, PhD, worked on the new Amborella genome analyses with Leebens-Mack and HudsonAlpha Faculty Investigators Jeremy Schmutz and Jane Grimwood, PhD. 

“Working on the original Amborella genome in Jim’s [Leeben-Mack] lab was transformative because it allowed me as a first-year PhD student to be on the very edge of newly developing technologies and software that was coming out to help handle all of this massive genomic data we were creating,” reflects Harkess. “This genome reveals so much about the evolution of flowers, but also about the evolution of my own research career and the way I, and now my entire laboratory, view reproduction through the lens of diversity.”

A tremendous achievement for Leebens-Mack and doctoral alumni from his lab. Key findings include the elucidation of a young sex-determination system in Amborella including identification of genes hypothesized to be responsible for sex determination. Whereas some aspects the Amborella's gene content and chromosomal structure seem to be quite ancient - dating back to the last common ancestor of all flowering plants - the Z and W sex chromosomes are young.  

Image: Male Amborella flower. Photo credit: Charlie Scutt