The evolution of plant life history strategies

September 15, 2016

Brachypodium sylvaticum

The evolution of plant life history strategies

David Des Marais (Senior Fellow of the Arnold Arboretum) has been awarded a grant from the Department of Energy’s Joint Genome Institute to investigate the genetic basis of annual and perennial strategies in plants.

Many plant species are characterized as either annual plants, which flower once and then die, or perennial plants, which flower over multiple growing seasons with periods of relative quiescence between them. The majority of the human diet is comprised of the seeds of annual plant species – corn, rice, wheat, and other cereals – which must be planted as seed at the start of each growing season and which die at the conclusion of that growing season. Annual plants in either agricultural or natural contexts typically only grow for a portion of a year, corresponding to the period when conditions are most favorable for their survival and reproduction. In effect, these plants can “wait out” poor growing conditions as seed. Perennials, on the other hand, must tolerate the full year’s range of climate. Many economically important plants, such as sugarcane and biofuel grasses such as switchgrass and Miscanthus, over-winter as root stocks and develop new above-ground vegetation each spring. For many perennial plants found in the world’s temperate regions, this means tolerating both the heat of summer and freezing temperatures of winter.

Dr. Des Marais will lead a team of scientists from the University of Wisconsin, the University of Vermont, Michigan State University, and the University of Zaragosa (Spain) to develop new genomic resources to study the genetic basis of evolutionary transitions between perenniality and annuality. Working with several species in the grass genus Brachypodium — growing in the Arnold Arboretum’s Weld Hill Research building — the team aims to identify genes and genetic control elements which allow plants to sense the environment and activate developmental pathways leading to senescence (in the case of annual species) or quiescence (in the case of perennials). The team will also evaluate how these differences in “life history” – annual vs perennial – are related to other aspects of plant-environment interaction such as cold tolerance, drought tolerance, and photosynthetic parameters. The work is a collaboration with the US DOE’s Joint Genome Institute, located in Walnut Creek, California.