A new plant evolution study shows scientists how some plants have evolved in order to prevent freezing. The new study, that was published in the journal ‘Nature’ by postdoctoral researcher Jeremy Beaulieu and his Colleagues, announces how researchers have found three traits that plants have developed while surviving colder temperatures. Scientists tracked down a multitude of plant trait data by using a variety of plant data bases that included thousands of species. The researchers recently mapped out the largest evolutionary time-scaled tree that included leaf and stem data which documented 32,000 species of flowering plants, also called angiosperms.
Plants can not generate heat by moving like animals in order to prevent freezing. When plant cells freeze, they expand and cause air bubbles that ultimately destroy and kill the cells. This obviously prevents the plant’s ability to move water and nutrients among transporter cells to any leaves or other structures. This is where plant evolution takes over with the three traits scientists have categorized.
The three discovered traits plants use to live under harsh colder temperatures included higher elevation and latitude data in regards to temperature differences. Plants that lose their leaves before any cold sets in, such as woody plants like Oak and Hickory Trees, gradually start to lessen water and nutrient availability and stop it all together in order to prevent freezing. When spring comes, these plants will then grow new transport cells and leaves. Other plants like poplars and birches grow very narrow water transport cells in order to prevent serious damage and blockages when cold weather hits them. While more herbaceous plants die back, drawing any energy from softer tissues above ground into their roots, only to re-sprout in the spring (such as bulbs and tuberous plants). The herbaceous plant traits also include seed producers that die back after they have successfully dispersed seeds that will sprout when the time is right.
During the studies, the data that was collected showed that herbaceous plants were actually well adapted to cold climates long before they even lived in them. This means the plants died back due to other problems before such conditions even affected them. So researchers figured that during herbaceous plant evolution they developed these abilities during other kinds of environmental stressors, such as drought survival. Plants that lose their leaves seem to be the only exception to this theory though.
The scientists plan to conduct further research in order to collect more data on various environmental conditions that include drought and extreme heat. Exploring the evolution of plants will obviously be tedious work due to the multitudes of species that will need to be detailed. The information that is being collected is coming from plants that are already well documented into data bases. This doesn’t include any plants that have yet to be discovered, such as in various rain forests and other areas that are difficult to explore. So in reality, this plant evolution study is just the beginning of learning how plants prevent freezing, other environmental challenges, including predator protection theories.
By Tina Elliott