Potential application of gamma-aminobutyric acid and endophytic bacteria in decreasing arsenic uptake in rice and enhancing rice yields

Arsenic (As) contamination in environment has been frequently reported in many areas worldwide, including Thailand. Arsenic is a toxic element and can accumulate in rice grains. It is a serious issue both for rice yield and quality, and for human health. Rice is the most important staple food in Thailand and other countries, especially South East Asia. Therefore, arsenic stabilization in soil for protecting its uptake to rice grains is an interesting method. Arsenic-resistant endophytic bacteria from rice grown in arsenic-contaminated soil and g-aminobutyric acid (GABA) addition has been showed ability in reducing arsenic in grains and increasing rice productivity. It might be due to endophytic bacteria can produce phytohormone (auxin) that affect reducing production of reactive oxygen species (ROS) during arsenic stress that leads to the tolerance in rice. With microbial addition, the high iron contents from siderophore production might be competed for uptake between iron and arsenic, thus affected on decreasing arsenic accumulation in roots. Moreover, GABA addition, may act as a central metabolite to ameliorate arsenic stress and regulate expression of responsive genes of rice, especially transporter genes that impact on reducing arsenic uptake and translocation in grains.