Sprouts of pyrethrum, a type of marguerite, get two types of substances from their mothers that protect them against outside threats. The mother plants give them pyrethrins to resist micro-organisms and foraging insects. In addition, the mother plants also supply substances which ensure that the sprouts can compete with small plants in their immediate environment. This is revealed by research by Plant Research International, part of Wageningen UR, published in the scientific journal Plant Cell in November 2012.
The outer cell layer of seeds, the seed wall, is really a layer of tissue from the mother plant within which the seed is formed. The tough seed wall protects the seeds against damage and other threats from the outside. Through the seed wall, the mother plant can supply substances to the seed which the seed or the sprout cannot make themselves.
A pyrethrum seed receives two special protections in the seed wall. Firstly, the mother plant ensures that the seed wall contains plenty of pyrethrins. The pyrethrins enter the embryo in the centre of the seed from the seed wall. At that point, this embryo is not yet able to make those substances itself. The mother plant gives pyrethrins because they protect the embryo against micro-organisms and insects during germination.
In addition, the mother plant produces glandular trichomes in the seed wall. These glandular trichomes contain very small droplets of so-called sesquiterpene lactones, substances which have been found to have the ability to inhibit the root growth of other plants. When the seed germinates, the sesquiterpene lactones enter the soil. The quantities involved are very small, but they are sufficient to inhibit the root growth of plants in the immediate vicinity. This gives the pyrethrum sprout a competitive advantage thanks to the mother plant.
The research took place in the context of a TTI Green Genetics project co-financed by two Dutch plant breeding companies.
Source: Hortitrends News Room
