Environmental and Genetic Control of Arsenic Accumulation and Speciation in Rice Grain: Comparing a Range of Common Cultivars Grown in Contaminated Sites Across Bangladesh, China, and India

Arsenic (As) contamination of soil is a serious problem limiting the rice grain nutrients production. Aim of this study was to identify the low grain As and sufficient selenium (Se) accumulating cultivars which may be suitable for human consumption and cultivation in As prone areas. Field trials at As contaminated sites of West Bengal, India were conducted to assess total As, inorganic arsenic (iAs) and Se content in rice grains by using HPLC-ICP-MS. Over a period of two years, 89 rice cultivars were cultivated at three different sites in West Bengal (India) having variable soil-As level. Selenium and As content in rice grains of various cultivars revealed that the number of safe cultivars decreased with increasing soil As level and also showed negative corelation (R=-0.997 **) between grain As and Se accumulation. However, total As content showed a positive correlation (R=0.903 *) with grain iAs content, while Se content in rice grains was negatively affected by As uptake. Only ten cultivars viz., IET-4786, CN1646-5, CN1794-2, Dusmix-40, S. Sankar, IR-64, IET-19226, Nayanmoni, CN1643-3 and CN1646-2 accumulating low grain As had sufficient Se. Therefore, cultivation of these ten genotypes may reduce the risk of possible dietary human As exposure and thus may be recommended for the cultivation in As affected areas in India.

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A molecular switch in sulfur metabolism to reduce arsenic and enrich selenium in rice grain

Nature Communications ◽

10.1038/s41467-021-21282-5 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Sheng-Kai Sun ◽

Xuejie Xu ◽

Zhong Tang ◽

Zhu Tang ◽

Xin-Yuan Huang ◽

...

Keyword(s):

Grain Quality ◽

Sulfur Metabolism ◽

Physical Interaction ◽

Rice Grain ◽

Yield Losses ◽

Serine Acetyltransferase ◽

Cysteine Synthase ◽

Arsenic Tolerance ◽

Arsenic Accumulation ◽

Low Levels

AbstractRice grains typically contain high levels of toxic arsenic but low levels of the essential micronutrient selenium. Anthropogenic arsenic contamination of paddy soils exacerbates arsenic toxicity in rice crops resulting in substantial yield losses. Here, we report the identification of the gain-of-function arsenite tolerant 1 (astol1) mutant of rice that benefits from enhanced sulfur and selenium assimilation, arsenic tolerance, and decreased arsenic accumulation in grains. The astol1 mutation promotes the physical interaction of the chloroplast-localized O-acetylserine (thiol) lyase protein with its interaction partner serine-acetyltransferase in the cysteine synthase complex. Activation of the serine-acetyltransferase in this complex promotes the uptake of sulfate and selenium and enhances the production of cysteine, glutathione, and phytochelatins, resulting in increased tolerance and decreased translocation of arsenic to grains. Our findings uncover the pivotal sensing-function of the cysteine synthase complex in plastids for optimizing stress resilience and grain quality by regulating a fundamental macronutrient assimilation pathway.

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