Mitigating Climate Change by Reducing Methane Gasses Production in Rice Fields

Previously, I wrote an article discussing about the paradigm shift of Agrobacterium-based genetic engineering which surprisingly also occurs naturally. Now, I also want to discuss almost similar topic, still related with transgenic organism, the difference is that my article now dealing with the application of transgenic organism for mitigating climate change effect.

The climate change is the warmer condition of earth as result of greenhouse gasses accumulation in atmosphere. This collection of gasses act like blanket where it shield the earth and don’t allow the reflected heat from earth to go outside atmosphere. There are two types of gasses which contribute to this effect; carbondioxide and methane. Greenhouse effect is largely caused by overproduction of carbondioxide which accounts for 80% of total gasses. However, one should notice that even tough methane only has 20% contribution, it is 100 time more potent in terms of trapping the heat. Hence, in terms of effect methane is being more harmful than carbondioxide that need to be seriously managed.

Mainly, the anthropogenic methane in atmosphere is originated from agricultural and livestock activities. Rice paddies, the common staple food for Asian, has largest role in producing methane, stands at 7-17% of the total gas. Interestingly, the methane is not directly produced by the rice itself, instead as result of the bacterial methanogenesis process in the waterlogged soil where the plant grows. The watered and anaerobic condition of soil are the most suitable place for methanogen bacteria activities. The strategy has been developed to mitigate this effect, however mostly in soil management area which often found was not effective. For instance, farmer in China regularly drying the soil and push oxygen into the soil to increase the crop yield and reduce the methane gas production. The farmer faced several obstacle of application of this water management method, due to the field drain unevenly and unregular rain pattern over the year. Thus, there is urge need to create sustainable rice farming by select the rice species with induce lowest production of methane from bacterial soil, and at the same time the species also has large harvest yield.

There is striking fact is that the methane production is largely depends on the root excaudate. Expert found that by shifting the carbon biomass allocation from the root into aboveground resulted in rice variant with high starch and low methane emission. Using transgenic rice which express transcription factor SUSIBA2, this aim can be achieved. The SUSIBA2 gene product responsible for shift in the carbon flux. The carbon biomass proportion is altered to be more in seed, stems instead of root. Thus, rice with high harvest yield is obtained due to increased content of seed’s starch. The cultivation of this type of rice also drops the production of methane as the decline in root’s excaudate suppressed the methanogen activity.

Personally, I think the approach perhaps beneficial in the future as high demand of rice makes the expansion of rice fields inevitable. By using the rice’s variant with high starch content with less methane emission, the effect of rice cultivation on climate change could be managed better.

This article is a summary from scientific article as follow : Expression of barley SUSIBA2 transcription factor yields high-starch low-methane rice. Nature 523,602–606, doi:10.1038/nature14673.

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