Booming growth in grazed plants
23 Sep 2011 by Evoluted New Media
Whatever doesn’t kill you can only make you stronger – and the age-old expression certainly holds true for plants.
Whatever doesn’t kill you can only make you stronger – and the age-old expression certainly holds true for plants. Scientists from the University of Illinois studied two cultivars of the Arabidopsis thaliana to see how they responded to being ‘eaten’. Of the 160 specimens studied, half were artificially grazed – clipped at their central stem – while the other half were not.
One of the cultivars – Columbia – rebounded dramatically after clipping, quickly regrowing stems and leaves, and producing more seeds than the unclipped plants. In the other cultivar, Landsberg erecta, growth remained steady after clipping, and the level of seed production remained the same.
Study of the number of chromosomes in the tissues of each plant before and after clipping revealed that Columbia was able to rebound in part by speeding up endoreplication – the ability to duplicate their chromosomes over and over again without undergoing cell division – in some tissues.
“The overall DNA content goes up in one of the cultivars after clipping, but it doesn’t change in the other,” said Ken Paige. “And we think it’s that added boost that increases its reproductive success.”
The added DNA content could allow the plant to increase production of proteins that are needed for growth and reproduction. More DNA means larger cells, said Daniel Scholes, Paige’s doctoral student, which can lead to bigger plants.
The researchers chose A. thaliana because it is known to repeatedly duplicate it’s chromosomes in some cells types. The plant begins with only 10 chromosomes – five from each parent – but after repeated duplications, some cells can contain up to 320 chromosomes.
“We tend to think that what you inherit is what you’re stuck with, Scholes said. “But we’re finding that plants are increasing what they have, and for the first time we’re beginning to understand how they do that and why.
This work – published in Ecology – is the first to link the seemingly miraculous burst of growth and reproductive fitness that occurs in many plants after they have just been grazed.
