"Saltwater Crops May Be Key To Solving Earth's Land Crunch"

Wired News is carrying a story by Alexis Madrigal on saltwater agriculture, focusing on a new Perspectives piece in Science by Jelte Rozema and Timothy Flowers.  Here is the opening paragraph from the Science piece, which contains some good numbers:

Currently, humans use about half of the fresh water readily available to them to support a growing world population [expected to be 9.3 billion by 2050]. Agriculture has to compete with domestic and industrial uses for this fresh water. Good-quality water is rapidly becoming a limited and expensive resource. However, although only about 1% of the water on Earth is fresh, there is an equivalent supply of brackish water (1%) and a vast quantity of seawater (98%). It is time to explore the agronomic use of these resources.

The authors go on to explore the many advantages, including 1) local agriculture (near coastal populations), 2) irrigation using seawater (yummy micronutrients as fertilizer), and 3) the utility of combined aquaculture practices.  The usual caveats about land use, local property rights, and environmental effects all apply.  But the numbers, at the depth presented, are impressive.

Here is a nice bit from Madrigal's story:

After taking into account environmental protections and other factors, [Robert] Glenn's report estimates that 480,000 square miles of unused land around the world could be used to grow a special set of salt-tolerant plants -- halophytes. Glenn's team calculated that this could produce 1.5 billion barrels of oil equivalent per year. That's 35 percent of the United States' liquid fuel needs.

Why aren't we already employing salt-tolerant plants to produce food and fuel?  Back to Rozema and Flowers:

...Although between 1996 and 2006 there were more than 30 reports of transformation of rice with different genes aimed at increasing salt tolerance, transgenic salt-tolerant rice is not close to release. The likely explanation is that salt tolerance is a complex trait determined by many different genes, so that transformation of multiple genes into a plant is required.

Wandering down this road a bit led me to Pamela Ronald's blog "Tomorrow's Table", one entry of which is up at the Nature Network and mentions local research in Bangladesh to create GM, salt-tolerant rice.  On a visit to Dhaka university, she explains the local imperative:

...Salinity is a problem for rice farmers here. Not only is the sea water rising, but fresh water supplies are under pressure partly because farmers are pumping more every year and also because Bangladesh is downstream from India, who gets first dibs on the fresh water through a network of dams. The result is that every year the saline lands encroach north, hurting rice yields, a serious problem here where the average Bengali receives 2/3 of their diet from rice.

The local research effort is proceeding both via breeding and genetic engineering.  Ronald writes of seeing "...Newly developed transgenic lines thriving under high salt concentrations that kill the conventional variety".  This is interesting both because the Bangladeshi team may be making progress and because a local team has taken on the task -- the country isn't going to be on any conventional list of biotech leaders.  So kudos to the local team.

What could we do to make this all go faster?  The story on salt-tolerance appears to be that it isn't yet a very well understood trait.  This means anyone interested in hacking plants to that end needs to have all the relevant genes and also a good way to get them into any given plant.

My guess is that this is going to start going a lot faster in systems where minichromosomes are up and running in plants of interest.  This will dramatically facilitate the insertion of genes into plants, without worrying about disrupting the endogenous genetic structure. I mentioned this in my post on SB 4.0, and just as a pointer here is the PLoS Genetics describing the creation of stably inheritable minichromosomes in Maize: "Meiotic Transmission of an In Vitro-Assembled Autonomous Maize Minichromosome".  Chromatin appears to have this technology working pretty well.  Recapitulating the work in rice and other crops will take time, of course, but my scrawled notes from Daphne Preuss' talk in Hong Kong suggest it went pretty fast in Maize once they figured out what they were doing.  I'll have more on this when I understand it better.