Nibbled? No Problem

Making extra copies of their genomes allows some plants to better withstand damage.

Feb 1, 2015
Ashley P. Taylor

DAMAGE CONTROL: A previously damaged Arabidopsis thaliana plant has regrown with multiple stems, a common response to herbivory. COURTESY OF DANIEL SCHOLES

EDITOR'S CHOICE IN GENETICS & GENOMICS

The paper
D.R. Scholes, K.N. Paige, “Plasticity in ploidy underlies plant fitness compensation to herbivore damage,” Mol Ecol, 23:4862-70, 2014.

The bite
You might expect that a plant would respond unfavorably to having its top bitten off by an herbivore. But as ecologist Ken Paige and colleagues at the University of Illinois at Urbana-Champaign first observed in the 1980s, some plants respond by making more seeds, ultimately benefiting from injury in a phenomenon called overcompensation. More recently, Paige and postdoc Daniel Scholes suspected a role for endoreduplication, in which a cell makes extra copies of its genome without dividing, multiplying its number of chromosome sets, or “ploidy.”

The response
Undamaged plants tend to increase their ploidy over time, but after experimental clipping, changes in ploidy diverge in different strains of Arabidopsis thaliana. To test the hypothesis that ramping up ploidy helps plants compensate for damage, the researchers overexpressed a gene called ILP1, known to cause endoreduplication, in a strain that ordinarily responds to clipping with undercompensation: decreasing seed yield and slowing of its normal rise in ploidy. They found that with the extra gene product, seed production and ploidy trends remained normal after clipping.

The conclusion
“The ploidy that the damaged plants are generating is directly influencing [their] ability to produce seeds when [they are] damaged,” says Scholes. To learn how genome duplications boost seed production, Scholes will start by determining which cell types endoreduplicate more after clipping.

Into the wild
Christopher Sacchi, a plant ecologist at Kutztown University in Pennsylvania, says he’s curious to see if the link between endoreduplication and overcompensation holds up in less-controlled circumstances. “They’ve got these very nice answers,” he says. “I’d like to see them take that to natural systems.”