Not a lot of people know that

22 Oct 2012

You can imagine Michael Caine saying ‘not a lot of people know that’ when you hear that more sunlight hits the surface of the earth in one hour than the entire human race uses in a whole year.

Solar panels can generate electricity from solar radiation but it is intermittent and difficult to store. Only plants, algae and some bacteria have the amazing ability to capture and store the sun’s rays as sugars using photosynthesis. Unfortunately, photosynthesis is quite an inefficient process. For instance, in wheat less than 1% of the intercepted solar radiation is converted into plant material over the life of the crop. This can creep up to just over 1% during the grain fill process.

There are three photosynthetic systems - C3, C4 and CAM. The main ones are C3 and C4 with wheat and rice using C3 photosynthesis and maize and sugar cane the C4 system. The C4 system is far more efficient in converting solar radiation than C3, particularly in warm climates; for example, sugar cane can be up to 7% efficient. This means that the C4 systems also tend to be more efficient users of nitrogen and water in terms of crop produced per unit of input.Leaf stomata

So research establishments are taking the first steps in trying to convert both wheat and rice from C3 to C4. There is no guarantee that they can achieve this goal or that the C4 system in these crops will provide the expected increases in productivity. However, it is a breeding goal that is well worth investigating.

One of the reasons for the recent plateau in wheat yields is that we have exhausted many of the technologies that produced the huge steps forward in the 1970s and 1980s. There is little doubt that plant breeding offers the major opportunity to provide the much needed yield improvements.

When you look back, the technologies that can now be used to improve crop performance through plant breeding are amazing. My A-level biology studies were totally disrupted by the teacher’s enthusiasm to discuss the early findings of Crick and Watson, shortly after each paper was published. Now plant researchers are in a good position to say what traits they would like to see in a plant and identify a method to achieve that end. No longer is plant breeding based on serendipity - in just crossing specific varieties and assessing the outcome by eye.

I may be doing pesticide discovery a disservice by saying that they still rely on serendipity by just testing a range of chemicals and seeing if they work. I realise that it has become more sophisticated over recent years with high throughput screening. However, I have yet to hear of a pesticide that has been discovered using the reverse process of getting an end point and working back to a pesticide that will achieve the result required.

Plant researchers are entering into new areas of opportunity. They now have the tools to design and make complicated biological molecules. The discipline is called synthetic biology and offers great opportunities. For instance they are trying to create an artificial system to mirror photosynthesis by stripping it back to a level of basic reactions where much higher levels of energy conversion are possible. In a world concerned about the implications of the current reliance on fossil fuels, the rewards for such an achievement would be huge.