Plants are altruistic too
Washington, Feb 2 : Dogs caring for orphaned kittens or chimps sharing food are all examples of animal altruism.
Now, a study led by the University of Colorado Boulder suggests some plants are altruistic too.
The researchers looked at corn, in which each fertilized seed contained two "siblings" -- an embryo and a corresponding bit of tissue known as endosperm that feeds the embryo as the seed grows, CU-Boulder Professor Pamela Diggle said.
They compared the growth and behavior of the embryos and endosperm in seeds sharing the same mother and father with the growth and behavior of embryos and endosperm that had genetically different parents.
"The results indicated embryos with the same mother and father as the endosperm in their seed weighed significantly more than embryos with the same mother but a different father," Diggle, a faculty member in CU-Boulder's ecology and evolutionary biology department said.
"We found that endosperm that does not share the same father as the embryo does not hand over as much food -- it appears to be acting less cooperatively," she said.
Diggle said that it is fairly clear from previous research that plants can preferentially withhold nutrients from inferior offspring when resources are limited.
"One of the most fundamental laws of nature is that if you are going to be an altruist, give it up to your closest relatives," co author Professor William "Ned" Friedman, a professor at Harvard University who helped conduct research on the project while a faculty member at CU-Boulder said.
"Altruism only evolves if the benefactor is a close relative of the beneficiary. When the endosperm gives all of its food to the embryo and then dies, it doesn't get more altruistic than that," he added.
The team took advantage of an extremely rare phenomenon in plants called "hetero-fertilization," in which two different fathers sire individual corn kernels, Diggle, currently a visiting professor at Harvard said.
The manipulation of corn plant genes that has been going on for millennia -- resulting in the production of multicolored "Indian corn" cobs of various colors like red, purple, blue and yellow -- helped the researchers in assessing the parentage of the kernels, she said.
The findings are published in the journal Proceedings of the National Academy of Sciences.