Plants have an altruistic side: study

The study led by the University of Colorado Boulder looked at corn, in which each fertilised seed contained two "siblings" - an embryo and a corresponding bit of tissue known as endosperm that feeds the embryo as the seed grows.

They compared the growth and behaviour of the embryos and endosperm in seeds sharing the same mother and father with the growth and behaviour 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," said Professor Pamela Diggle, a faculty member in CU-Boulder's ecology and evolutionary biology department.

 

"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," Diggle said in a statement.

Diggle said it is fairly clear from previous research that plants can preferentially withhold nutrients from inferior offspring when resources are limited.

"Our study is the first to specifically test the idea of cooperation among siblings in plants," she said.

In corn reproduction, male flowers at the top of the plants distribute pollen grains two at a time through individual tubes to tiny cobs on the stalks covered by strands known as silks in a process known as double fertilisation.

When the two pollen grains come in contact with an individual silk, they produce a seed containing an embryo and endosperm. Each embryo results in just a single kernel of corn, said Diggle.

The team took advantage of an extremely rare phenomenon in plants called "hetero-fertilisation," in which two different fathers sire individual corn kernels, said Diggle.

Researcher Chi-Chih Wu, who cultivated the corn and harvested more than 100 ears over a three-year period, removed, mapped and weighed every individual kernel out of each cob from the harvests.

While the majority of kernels had an endosperm and embryo of the same colour - an indication they shared the same mother and father - some had different colours for each, such as a purple outer kernel with yellow embryo.

The study was published in the journal Proceedings of the National Academy of Sciences.