We need you!

Are you interested in becoming a GrassPortal user? We are presently recruiting potential users to test the beta-version of the portal (towards the end of August 2010) before it goes publicly online and would like to offer this opportunity to all our blog readers / facebook fans / twitter followers.

As part of the portal development strategy we would like users to take part in an online survey. This suggests a number of different scenarios for the use of GrassPortal and then asks a number of questions related to these scenarios to help us decide on the ultimate structure and content of GrassPortal. This is a very important part of the portal design as it will tell us what users actually do and don’t want from GrassPortal.

If you are interested in becoming a user of the beta-version of the portal, and are willing to take part in our survey, please get in touch with Vernon (vernon@grassportal.org) or Colin (colin@grassportal.org) for further information.

Into the sunshine

A recent paper in PNAS by Erika Edwards (one of our GrassPortal partners) and Stephen Smith provides some novel insights into the environments in which grasses evolved and why certain groups of species are associated with warm or cool regions of the earth. Contemporary tropical and sub-tropical grasslands are dominated by C4 grasses (grasses with “turbo-charged” photosynthesis. See our recent blog post) and temperate grasslands tend to be dominated by C3 grasses. This has led to the long-standing belief that C4 photosynthesis is better adapted to warmer environments.

By reconstructing the evolutionary relationships among grass species, Erika and Stephen have been able to show that our view on this problem may be skewed.  The origin of grasses seems to have been in the shade of tropical forests, and evolution has subsequently taken very different turns in two of the major grass lineages. In the first, the evolution of C4 photosynthesis seems to have been associated with a shift to drier, and more open savannas and grasslands in the tropics - so the C4 pathway may be an adaptation to bright tropical sunlight and drier soils.  In the second lineage, grasses have evolved cold tolerance, allowing them to radiate out from the tropics and into the cool temperate regions. Here, it is the ability to survive cold conditions, rather than the C3 photosynthetic pathway, that allows these species to grow in temperate climates.

This new work forces us to look at the distribution of grass species in a new way, and clearly highlights the importance of using evolutionary relationships to understand geographical patterns. GrassPortal will make this kind of work significantly easier to carry out in future, providing direct links between phylogenetic (evolutionary relationships) and biogeographic (species distributions) data.

Turbo-charged grasses

Life on Earth would not work without photosynthesis - the process used by green plants to convert atmospheric carbon dioxide and water into sugars.  Almost all of the living things (with a few exceptions in the deep sea) depend on this process to grow and survive - plants use photosynthesis directly as a source of energy and the building blocks for growth.  Animals consume plants (and each other) to acquire the same resources for life. Humans are no exception - we eat crops and animals that are raised on plants and, to a large extent, these plants are grasses (comprising more than 50% of our calorie intake).

Most of the world's plant species use a basic model of photosynthesis, called the C₃ pathway.  But around 4% have an upgraded form called C₄ photosynthesis. Among grasses, the usage of this pathway is much more common, with about half of the world's grasses using C₄ photosynthesis. Plants with the C₄ photosynthetic pathway rank among the world's most important crops and noxious weeds. Maize, Sorghum and Millet are staple foods throughout the tropics, Sugarcane is traded globally, and 14 out of the world's 18 worst weeds are C₄ plants.

The C₄ pathway is a fuel injection system for photosynthesis that increases the rate of sugar production in hot climates by overcoming an inefficiency of the C₃ type arising at high temperatures. It is an add-on to the regular C₃ pathway. In the leaf of a C₄ plant, the C₃ pathway is isolated from the atmosphere in a specialized cellular compartment. The C₄ cycle pumps carbon dioxide into this compartment to saturate the C₃ photosynthetic enzymes, allowing them to operate super-efficiently, and at high rates.  It is no coincidence that the most productive plants on Earth are C₄ grasses.

More details on how the process works

GrasPortal should help us to better understand how C₄ photosynthesis has evolved in grasses. We already know that the pathway has evolved at least eight times in this group (and probably more).  As the evolutionary relationships between grass species become better understood, this picture should become clearer.  Recent work has also shown that open conditions (no shading from trees) are important for this evolutionary transition, and that the evolution of C₄ photosynthesis has been crucial in allowing grasses to move into drier habitats. GrassPortal will aid the research in this area by allowing us to map the environmental preferences of each species onto the evolutionary tree of life.  By doing this, it will help us  to discover more about how the C₄ pathway has evolved, and the new ecological opportunities it has brought for grasses.

Grass Phylogeny Working Group

Reconstructing the evolutionary tree of life (phylogeny) is a major goal in biology right now.  Leaving aside the question of whether the "tree" is better described as a "thicket" (more and more evidence does seem to be pointing in that direction), this is a massive undertaking.  The economic and ecological importance of grass species is good news on this front - it means that the grass family (Poaceae) is one group that evolutionary biologists are already working hard on.

Some of our partners on the GrassPortal project are driving the ongoing efforts in this area.  Erika Edwards at Brown University, Nicolas Salamin at the University of Lausanne and Stephen Smith at the National Evolutionary Synthesis Center (NESCent) are leading an international group tackling this problem. The evolutionary tree they come up with will go straight into the GrassWeb project at Lausanne, where GrassPortal will pick it up.  More details from NESCent:
NESCent grass phylogeny working group

GrassPortal - how it's all fitting together

Was asked to give a talk about GrassPortal at the JISC Annual Conference a couple of weeks ago.  It seemed to go down well, and the full presentation should be up on the JISC site shortly. Will link to it in a future entry but, for now, wanted to share one particular slide from the talk.  It's a new schematic of how the GrassPortal project is all fitting together.

The grass phylogeny from the GrassWeb project at Lausanne links together the species names and descriptions from Kew. These species names, in turn, link together the species occurrence data from GBIF.  And each of these occurrences maps onto multiple environmental datasets. Hopefully the picture should make this clearer!