Cultivar variation in brown rice inorganic arsenic accumulation

Authors: Fernandez-Baca, Cristina; Codling, Eton; Reddy, Vangimalla; McClung, Anna; Barnaby, Jinyoung

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/24/2019
Publication Date: 4/24/2019
Citation: Fernandez-Baca, C.P., Codling, E.E., Reddy, V., McClung, A.M., Barnaby, J.Y. 2019. Cultivar variation in brown rice inorganic arsenic accumulation [abstract]. 30th Annual Beltsville Poster Day.

Interpretive Summary:

Technical Abstract: Consumption of rice containing high levels of arsenic (As) is linked to adverse health impacts including cancer in humans. However, long-term low-level exposure is less well understood. FAO/CODEX and the FDA have both created limits on inorganic As (iAs) in milled rice. The FAO/CODEX limit for rice grain iAs is 200 ppb, while the FDA has set a more stringent limit of 100 ppb iAs in rice-based infant foods. Brown rice iAs limits are under consideration. It is important for US rice to meet both national and international rice quality standards as half of US-grown rice is exported. Rice accumulates As at higher concentrations than other cereal crops because it is commonly grown under continuously flooded (FLD) conditions. Flooded rice paddies create anaerobic conditions favorable for soil As release and thus As availability for rice plant uptake. Management practices such as alternate wetting and drying (AWD) for growing rice have become popular in recent years as a means to save water, moreover under aerobic conditions, rice As concentrations significantly decrease. Rice varieties have previously been shown to differ in grain As uptake, suggesting selection of low As accumulating rice cultivars can mitigate rice grain iAs. To study the effect of rice genotypes on rice grain As accumulation, a mapping population of chromosome segment substitution lines (TILs) was evaluated. The TILs were grown in the field under FLD or AWD irrigation management practices during 2013 and 2014 in Stuttgart, AR. Days to heading (DTH), one of the potential controlling factors in As reduction, were recorded, and grain samples were collected at harvest to measure final yield and inorganic As. In 2014, rice genotype appears to significantly impact iAs rice grain accumulation under AWD irrigation management. Data from 2013 did not show any trends with either rice genotype or irrigation treatment and grain iAs accumulation; however, 2014 data showed significant reductions in grain iAs under AWD for all TILs as compared to FLD. Likewise, parents of the TILs, Lemont and TeQing, as well as Francis, Rondo, Katy, and PI 312777 showed significant decreases in grain iAs under AWD. Rondo and PI 312777 had the greatest reduction in grain iAs concentrations which were greater than 120 ppb under FLD and were reduced to 50 to 55 ppb under AWD. Lemont, Francis, and TeQing had the lowest grain iAs under AWD, with a range of 16.2 to 25 ppb. Fifteen of the TILs had even lower grain iAs (<10 ppb) under AWD. All TILs and parent lines reduced grain iAs levels below the FDA limit of 100 ppb under AWD in 2014. These results suggest that rice grain iAs can be controlled by selecting and utilizing rice cultivars that have low iAs accumulation under water saving practices like AWD.