I currently have an experiment in progress with the goal of testing if AM fungi aid in the establishment of seedlings that exhibit epicotyl dormancy. One of the experimental treatments involves planting a seed with that trait along with seedlings of Sugar Maple (Acer saccharum). The Sugar Maple is included as a carbon source in the symbiotic relationship. The reason I am using Sugar Maple is that it forms mycorrhizae with AM fungi, unlike most other trees which associate with ectomycorrhizae.
Unfortunately the germination rates for the Sugar Maple seeds have been very poor so the experiment is not likely to yield results that would survive peer review. However, those that have are already exhibiting what appears to be a significant difference in size between the treatments with AM fungi and those without.
The Maple seedlings on the right were treated with spores of several Glomus spp. shortly after germination. The seedlings on the left were grown in sterile media with no Glomus spp. In a few months I plan to remove the seedlings, dry them and then weigh them. A portion of the roots will be saved and examined for the presence of aseptate hyphae.
I’ve been watching March Madness on demand (ncaa basketball) and just about every other commercial has been for ExxonMobil’s foray into algal oil research. Having studied algae a bit this subject has peeked my interest. Exxon has partnered with Synthetic Genomics, Inc to study the potential of algae as a source of bio-fuels and is expected to devote in excess of $600 million to this research.
This is not an entirely new concept but it appears to be one of the largest investments in algal oil research to date. A great deal is known about culturing algae for other uses. Algal cultures are used extensively in aquaculture of clams and oysters. About 40% of the costs of producing juvenile bivalve seed in a hatchery is from the production of algae cultures.
Many algae reproduce rapidly when sufficient light, CO2, and nutrients are supplied. Anyone who has kept an aquarium or pond is probably familiar with algae blooms. Commercial ventures must maintain pure stock cultures since eventual contamination with other organisms eventually causes algal populations to crash, and this adds to the cost of culturing algae on a large scale.
It happens that many of the species that my students examine in the classroom have been investigated as possible algal oil sources. These include the filamentous green algae Oedogonium and Spirogyra. These are probably more familiar to people as components of “pond scum”, which makes the potential use of these organisms for bio-fuels all the more interesting.
Algae in the genus Spirogyra are known for their unbranched, filamentous thalli containing long, spirally arranged chloroplasts within each cell.
Sexual reproduction in Spirogyra occurs via conjugation, where two adjacent filaments form connections (conjugation tubes). The contents of the joined cells serve as isogametes (Raven et al., 2007). In the images below the isogametes from one filament can be seen moving into the cells of another filament. Where they meet they form a zygote.
Raven, P.H., Evert, R.F., and S.E. Eichhorn. 2007. Biology of Plants, 7th ed. Worth Publishers, Inc., NY.
I have been experimenting with creating videos of plants lately. This one was shot using a webcam and it worked reasonably well.
This is an example of a nastic response to a stimulus. Specifically it is thigmonasty, a non-directional response to touch or vibration. The leaf of a venus flytrap is divided into two lobes, each of which bears three trichomes (hair-like structures). The closing of the “trap” is triggered by touching one of the little trigger hairs twice or by hitting two of them in succession. Somehow this causes a change in turgor pressure in the cells of the leaf and a rapid change in shape, allowing the trap to close rapidly.