Evolutionary genetics of vernalization responsiveness in the temperate grass subfamily Pooideae

University Of Vermont & State Agricultural College, Burlington VT

Investigators

Abstract

Jill Preston IOS-1353056 Evolutionary Genetics of Vernalization Responsiveness in the Temperate Grass Subfamily Pooideae Most plant species integrate multiple environmental cues, such as day length and past winter chilling, to ready them to flower when local conditions are favorable. Not only does flowering time affect plant fitness, but also the yield of grains, fruits, and seeds available for human consumption. But how do plants in different climates know to vary their flowering times, and what happens as these local climates change over time? To address these questions, this project focuses on a geographically and ecologically diverse group of cereal crop and forage grasses with the aim of determining how flowering time has evolved at both the whole plant and genetic level under global cooling over the past 50 million years. By shedding light on the past, results of this study promise to allow better prediction of flowering time responses to current global change, and to isolate novel genes and genetic pathways for the potential manipulation of flowering time in crop grasses. The "pooid" grasses evolved from a tropical ancestor around 48 million years ago and have subsequently colonized a wide range of habitats in both the northern and southern temperate zones as global temperatures decreased. One of the major barriers to living in the temperate region is freezing temperatures, which are particularly detrimental to reproductive structures. The crop pooids barley, wheat, and oats are able to avoid flowering in winter by rapidly becoming competent to flower after an extended period of cold tempreatures (vernalization). However, it is unknown whether the evolution of the vernalization response was key to the diversification of all temperate pooids, or if it evolved more recently in separate grasses. To determine the evolutionary origin(s) and genetic basis of the vernalization response, the PI will work with students, a postdoctoral researcher, and computer scientists in the Vermont Genetics Network to carry out flowering time experiments on 40 species of pooid grasses collected from different latitudes across the world. The flowering time response of each species to cold temperatures will be mapped onto an evolutionary tree and models will be used to estimate when and how many times flowering in response to cold evolved. As a complement to this, genomic data will be collected to pinpoint similarities and differences in vernalization responsive gene expression between species. By determining different levels of plant responses to chilling, data from this project will facilitate critical insights into the complex adaptations of plants to their environments. Furthermore, activities and outcomes of this study will be used to foster interdisciplinary and active learning activities for high school to graduate students, paving the way for the next generation of successful organismal and evolutionary biologists.