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Prelims Syllabus : WaarsM Gene Mains Syllabus : Increase in arsenic accumulation in rice - ways to control

Why in News?

  • Arsenic accumulation in rice grains is one of the serious agricultural issues in India.
  •  To address this, researchers at Lucknow-based CSIR-National Botanical Research Institute have developed transgenic rice by inserting a novel fungal gene, which results in reduced arsenic accumulation in rice grain.

WaarsM Gene:

  •  Researchers have cloned Arsenic methyltransferase (WaarsM) gene from a soil fungus, Westerdykellaaurantiaca.
  •  They inserted the same into the rice genome with the help of Agrobacterium tumefaciens, a soil bacterium which has natural ability to alter the plant’s genetic makeup.
  • The newly developed transgenic rice along with normal rice was then treated with arsenic.
  • Researchers found that the resulting transgenic plant acquired the potential for methylating inorganic arsenic to a variety of harmless organic species, including volatile arsenicals.
  • This could be potential strategy for developing transgenic rice capable of low arsenic accumulation not only in grain but also in straw and feed which are used for livestock.

Significance of WaarsM Gene:

  • The genetic modification of rice grain can be applied to develop practices to decrease accumulation of arsenic by molecular breeding, gene editing or transgenic approaches.
  • As large numbers of people are affected by arsenic toxicity, it is imperative to develop rice with lesser arsenic content and high yield.
  • Other Researches:

    •  In the past, it has shown a transgenic approach in which phytochelatin synthase from Ceratophyllumdemersum (an aquatic plant) was expressed in rice.
    • Transgenic lines showed enhanced accumulation of arsenic in roots and shoot but less in grains.
    • They also described that over expression of OsGrx_C7 (protein found in rice) enhanced tolerance to arsenite and reduced arsenite accumulation in seeds and shoots of rice.
    • Recently, they have showed that OsPRX38 transgenics accumulate less arsenic due to high lignification in root which acts as a barrier for arsenic entry in transgenic plants.
    •  In this background, biotechnological methods such as modulating the expression of Arsenic metabolism-related genes in rice will be a fruitful and practical approach to decrease arsenic accumulation.
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