http://www.nytimes.com/2016/11/18/science/gmo-foods-photosynthesis.html
The research involves photosynthesis, in which plants use carbon dioxide from the air and energy from sunlight to form new, energy-rich carbohydrates. These compounds are, in turn, the basic energy supply for almost all animal cells, including those of humans. The mathematical description of photosynthesis is sometimes billed as “the equation that powers the world.”
For a decade, Dr. Long had argued that photosynthesis was not actually very efficient. In the course of evolution, several experts said, Mother Nature had focused on the survival and reproduction of plants, not on putting out the maximum amount of seeds or fruits for humans to come along and pick.
When plants receive direct sunlight, they are often getting more energy than they can use, and they activate a mechanism that helps them shed it as heat — while slowing carbohydrate production. The genetic changes the researchers introduced help the plant turn that mechanism off faster once the excessive sunlight ends, so that the machinery of photosynthesis can get back more quickly to maximal production of carbohydrates.
http://www.news.cornell.edu/stories/2014/09/plant-engineered-more-efficient-photosynthesis
A genetically engineered tobacco plant, developed with two genes from blue-green algae (cyanobacteria), holds promise for improving the yields of many food crops.Plants photosynthesize – convert carbon dioxide, water and light into oxygen and sucrose, a sugar used for energy and for building new plant tissue – but cyanobacteria can perform photosynthesis significantly more quickly than many crops can.
Though others have tried and failed, the Cornell and Rothamsted researchers have successfully replaced the gene for a carbon-fixing enzyme called Rubisco in a tobacco plant with two genes for a cyanobacterial version of Rubisco, which works faster than the plant’s original enzyme.
http://www.pri.org/stories/2016-01-13/researchers-around-world-are-exploring-how-gmo-technology-might-boost-food
At Oak Ridge National Laboratory in Tennessee, staff scientist Xiaohan Yang is trying to discern the genetics behind a kind of photosynthesis that’s different from that used by most common crops. His subject? Agave, the hardy desert succulent that is the basis of tequila.Most plants use types of photosynthesis known as C3 or C4, in which they open their stomata during the day to take in carbon dioxide. Agave uses a different kind of photosynthesis, called crassulacean acid metabolism, or CAM. The plant opens its stomata at night to absorb carbon dioxide, when temperatures are cooler, then stores the carbon in a temporary pool of malic acid, thereby losing less water to transpiration. When the sun comes up, agave releases the stored carbon to complete photosynthesis without opening its stomata.As a result, CAM plants survive on as little as one-fifth as much water as C3 and C4 plants.
http://www.natureworldnews.com/articles/9442/20141007/scientists-want-improve-photosynthesis-good-idea.htm
The emergence of the photosynthetic process is one of the landmarks in the biological processes on earth two billion years ago, which flooded the earth's atmosphere with oxygen. But this was not a plant-based innovation.
Photosynthesis is one of the earliest forms of energy production, arising and most likely prompting a key moment in Earth's primordial history called the Great Oxidation Event (GOE) more than two billion years ago.However, it wasn't complex plant life that prompted the GOE. It has long been suspected that cyanobacteria, the same blue-green algae we see in our oceans today, were the first to get the GOE rolling by belching out dioxide (O2) as they used sunlight and carbon dioxide (CO2) to make energy.And like any great classic, the photosynthetic process of blue-green algae appears to be better than any later versions adapted by plants on land.That's apparently why scientists have been struggling to slip the cyanobacteria's more efficient photosynthetic mechanisms into the world's most important crops.
One central question is whether turbo-charged photosynthesis is really needed. There might not be a need to turbo-charge the growth of agricultural crops because demand for these crops is not rising. That is, although farm productivity has largely plateaued, so has consumption.
"We are truly excited about the findings of this study. Wheat yields in the UK in recent years have reached a plateau. In order to increase wheat yields in a sustainable manner in the future, we are looking at a variety of approaches," said Martin Parry, the lead Rothamsted researcher. "The present study has been undertaken in a model plant species and it represents a major milestone. Now we have acquired important knowledge and we can start taking further steps towards our goal of turbo-charging photosynthesis in major crops like wheat."
But while a high yield "super-crop" sounds like a boon for wheat farmers, is it really necessary?
Despite its plateau in the United Kingdom (UK), wheat production doesn't appear to be getting outpaced by demand. According to the US Department of Agriculture's (USDA) World Agriculture Outlook Board, consumption of wheat for 2014/2015 has increased by only 3.2 million tons, while overall world production has risen by 3.9 million tons within the same window of time. This is despite the fact that drying in some regions like Australia and the United States has led to a notable drop in production this growing season.
Moreover, by current methods of innovation, crop productivity can increase dramatically in the future without turbo-charging photosynthesis.
Additionally, researchers recently determined that the Earth's maximum plant production is "roughly two orders of magnitude higher than the productivity of most current managed or natural ecosystems," meaning we have a ways to go before the entire potential for growth maxes out.That is, at least according to Evan DeLucia, who led an analysis of the "theoretical limit of terrestrial plant productivity," which was recently published in the journal Environmental Science and Technology.Interestingly, the researcher conducted his assessment with both predicted climate change factors and the theoretical maximum potential of photosynthesis in mind. That means that to reach this ideal productivity, the world's plants would all have to have achieved their peak potential through natural selection, or - more likely - genetic editing.Imagine what his numbers would have been had he taken into account Parry's "turbo-charged" photosynthesis! Global starvation suddenly seems a near-impossibility."I don't want to be the guy that says science is going to save the planet and we shouldn't worry about the environmental consequences of agriculture, we shouldn't worry about runaway population growth," DeLucia said in a statement "All I'm saying is that we're underestimating the productive capacity of plants in managed ecosystems."
Improving plant photosynthesis also raises the specter of escaped plants becoming invasive species -- a risk of traumatic ecological disruption that typical GMOs do not present.
But while some tamer genetically modified organisms (GMO) and genetic editing strategies may be accepted by the scientific community as safe and effective, they might not say so of "turbo-charged" plants."Upgrading photosynthesis is a different story," writes Micheal Le Page, an editorial writer for New Scientist magazine. "If biologists succeed in boosting it by 25 percent or more, the upgraded plants are going to have a big advantage over their unmodified cousins. And that could spell trouble."The science journalist argues that while many of the strange traits selected for in GMO crops - like resistance to herbicides - are unlikely to make them a successful invader in the natural environment, supercharging photosynthesis would be like giving steroids to only one team in an entire football league.If supercharged plants, like the model tobacco plant mentioned above, were to ever accidentally escape from a controlled environment into the wild, they would wreak havoc on ecosystems, out competing even the strongest of natural flora simply because of their remarkable efficiency.
Turbo-charged photosynthesis would be a particular advantage in the face of global warming, making the plants especially dangerous to contemporary or future ecosystems.
Improved photosynthesis would make these plants more resistant to climate change, too. In drought environments, which are becoming more prevalent in the Northern Hemisphere, they would flourish, as any plant with adequate energy reserved doesn't have to open its pores as much, meaning it can better retain moisture.
But are GMO invasive species such a problem in a world that has ecosystems under pressure? Paradoxically, humans may need to terraform the Earth in the future.
Interestingly, Le Page does not seem entirely set against letting improved plants run wild, despite the fact that it would radically alter the natural world."This may seem like a shocking idea. But the reality is that we are way, way past the point where we can preserve Earth the way it was before we came to the fore," he writes. "If we are going to reshape plants so that they can make more food, why not do it in a way that benefits most life on Earth, not just us humans?"It's a novel idea, leveling the playing field by improving all plants, or at least those carefully selected by humanity, but implementing it seems a lot like fantasy, at least for now.
From an MIT group on water security:
"Genetic modification can decrease the water requirement by selection for traits that
(1) increase the rate of photosynthesis and
(2) depth of root structure, as well as
(3) decrease the rate at which water is lost through transpiration."
-Monsanto, an agricultural biotechnology company, is researching transgenes of the family of cold-stress proteins, CspA and CspB, which, if copied and inserted into corn crops, can increase the plants’ abiotic stress tolerance, or rather, increase the plants’ ability to prevent water loss to the environment [5].
-Other ideas being investigated include increasing sensitivity to abscisic acid, which causes the stomates to close rapidly under stressful conditions [5]; the stomates are responsible for monitoring the rate of transpiration, meaning that stomates that close quicker in dry or windy conditions will promote less water from leaving the plant and transpiring into the atmosphere.
-Lastly, the DREB and CBF transcription factor families are also candidate genes to alter – they may reduce the drought-induced oxidant load that leads to tissue damage, however, if over-expressed, they stunt plant growth [5]. After further research and development, such genetic improvements should be implemented into current maize species.
-The gene Arabidopsis HARDY has the effect of increasing the water efficiency of rice by increasing the rate of photosynthesis, and decreasing the amount of water loss through transpiration [7]. Modification of this gene has also been shown to increase the strength and amount of root structure of the plant. Plants with the HARDY gene have shown a 55% greater photosynthesis rate under normal conditions [7].
-In addition, a recently discovered gene, DRO1, has been observed to increase the root depth of the plant, and thus make the plant more drought resistant [8]. Tests done with this gene spliced into the common paddy rice found that the crop performed equally well under moderate drought conditions versus drought-free conditions, and yield only fell by 30% under severe drought conditions [8]. These modifications translate into a more efficient use of water by the rice plant and increase drought resistance and salt tolerance [8], and thus should be further researched and developed for global use.
-Genetic modifications of the wheat plant focused on particular parts of the plant, such as the root systems, and processes, such as transpiration, that can increase water use efficiency by the plant. Wheat can be genetically modified to have deeper roots by extending the vegetation period of the plant through selection for later-flowering genotypes. Deeper root systems promote more water uptake, which means the plants require less irrigation and perform better under drought conditions. An example of a current strain of drought tolerant wheat is SeriM82, also known as “stay-green wheat” which has been shown to have deeper root systems which lead to greater water uptake. One simulation has shown this increased water uptake during drought periods can lead to a 14.5 percent increase in yield [10].
-Plants can also be selected for longer coleoptile growth, which is achieved through selection for certain semidwarf wheat populations. These plants tend to have faster initial growth and better crop establishment, which leads to a more efficient use of water.
-Another genetic modification for drought resistance currently being researched is greater transpiration efficiency. Modifications to decrease the amount of transpiration, or water loss, that occurs through the leaves of the plant include selection for greater leaf reflectance of light, smaller leaf surface, and methods to decrease the cuticular water loss. In order to increase the reflectance of leaves, selection can target for glaucousness in wheat plants (the gray blue waxy coating that some leaves have). This can also be achieved by selection for pubescence, the hairy surfaces on leaves that reflect light. These modifications should lead to less evapotranspiration through the leaves, and therefore more efficient water use [11].
