Breakthrough in efforts to supercharge rice and reduce world hunger

[muriel_volestrangler]

Rice uses the C3 photosynthetic pathway, which in hot dry environments is much less efficient than the C4 pathway used in other plants such as maize and sorghum. If rice could be ‘switched’ to use C4 photosynthesis, it could theoretically increase productivity by 50%.

The new study, published in the journal Current Biology, recreates the first step of the likely three-step evolutionary process that transitioned C3 plants to the C4 pathway.
...
The C4 photosynthetic pathway, which has evolved over 60 times independently, accounts for around a quarter of primary productivity on the planet despite being used by only 3% of species. In most C4 plants, photosynthetic reactions happen in two types of cell arranged in ‘wreaths’ around closely spaced veins – an arrangement referred to as Kranz anatomy. One of the major challenges of the C4 Rice Project is to convert rice leaf anatomy to this form.

In this study, researchers demonstrate how they took the first step on this journey – the step towards a ‘proto-Kranz’ anatomy – by introducing a single maize gene known as GOLDEN2-LIKE to the rice plant. This had the effect of increasing the volume of functional chloroplasts and mitochondria in the sheath cells surrounding leaf veins, mimicking the traits seen in proto-Kanz species.

http://www.ox.ac.uk/news/2017-10-19-breakthrough-efforts-%E2%80%98supercharge%E2%80%99-rice-and-reduce-world-hunger#

The paper: http://www.cell.com/current-biology/fulltext/S0960-9822%2817%2931238-1

An explanation of what the 'C3' and 'C4' mean:

First, you all know that plants make sugar from carbon dioxide and sunlight. They use photosynthesis in a set of light reactions to produce energy (in the form of reducing compounds and ATP) that are passed on to a pathway called the Calvin cycle, which fixes CO2 into carbon compounds. It does that by adding the carbon in CO2 to a 5-carbon sugar called ribulose bisphosphate, producing a 6-carbon molecule that is immediately split into two 3-carbon molecules, called 3-phosphoglycerate or 3PG. The enzyme that carries out this reaction is called rubisco, and it’s not particularly efficient. In fact, it’s kind of terrible — it works poorly in a low CO2 environment (like modern Earth!), and plants can lose 25% of their energy to a reaction with O2, rather than CO2. The Calvin cycle is thoroughly intertwined with all kinds of reactions in plant biochemistry, though, so it’s pretty much indispensible. There isn’t an alternative, more efficient reaction that can substitute for it.

Evolution has been creating workarounds, though! Some plants have evolved a kind of supercharger for CO2 — they use an alternative enzyme, PEP carboxylase, to fix CO2, adding the carbon to a 3-carbon intermediate, phosphoenol pyruvate, to produce a 4-carbon molecule, oxaloacetate, which is then passed along to other cells where the carbon is cleaved off to form CO2 again, which sounds kind of pointless, I know…except that what it does is create a CO2-rich environment in the destination cells, so rubisco can run much more efficiently. See? A turbocharger for plant sugar synthesis.

https://freethoughtblogs.com/pharyngula/2017/10/26/borrowing-from-evolution-to-create-more-efficient-crops/

[democratisphere]

1. I'm really not sure "frankenfood" is a good idea.

Where you may gain in one aspect, you are certain to lose in another.

[hlthe2b]

2. Besides the fact that rice is grown in some of the most Arsenic-laden soils and water...

Even in the US, that is problematic. Ironically, rice grown in many areas of India have lower arsenic levels than does that grown in Texas. But naturally occurring (or human-contaminated) arsenic soils is a big problem, no matter how "nutritious" the rice is made to be.

[Igel]

4. Or more importantly that because of the way rice grows

it's more likely to pick up higher concentrations of arsenic than other grasses regardless of the arsenic content of the soil.

The response to having rice grown in lots of water is to soak your rice ahead of time.

Ironically, in places like India, that's what they do.

Can't do that with the usual long-grain rice for sale in the US because of the additives that coat the rice. Soak rice, lose arsenic, lose vitamins.

Not sure the soaking would have much effect on brown rice.

However, the biologically engineered rice wouldn't affect this problem. It would just produce more rice, not force people to eat it; for people who eat a lot of rice, there's no tradeoff. For people who don't eat much rice because they're impoverished, it's a net gain, all things considered. For people who don't each much rice because they don't eat much rice, well, it's already cheap and it's unlikely to alter their diet.

[NNadir]

3. This will go the same way as golden rice. Fear and ignorance will prevent the technology from...

...doing what it might have done, and the people who can least afford it - the poorest of the poor - will suffer because bourgeois brats completely lacking in a shred of scientific education will dress up in monkey suits - I'm of course referring to the asses at Greenpeace - to protest it.

Basically we have creationists of the left equally as onerous as those on the right, in fact, in some ways actually worse: The hatred for science on the right is simply denial; on the left it is active opposition.

There are people on this planet who are blind because of a disgusting effort to prevent the gene for vitamin A from being inserted into rice.