Toxicity and bioaccumulation of two non-protein amino acids synthesised by cyanobacteria, β-N-Methylamino-L-alanine (BMAA) and 2,4-diamino-butyric acid (DAB), on a crop plant

In order to study the toxicity of the cyanobacterial non-protein amino acids (NPAAs) L-beta-N-methylamino-Lalanine (BMAA) and its structural isomer L-2,4-diaminobutyric acid (DAB) in the forage crop plant alfalfa (Medicago sativa), seedlings were exposed to NPAA-containing media for four days. Root growth was significantly inhibited by both treatments. The content of derivatised free and protein-bound BMAA and DAB in seedlings was then analysed by LC-MS/MS. Both NPAAs were detected in free and protein-bound fractions with higher levels detected in free fractions. Compared to shoots, there was approximately tenfold more BMAA and DAB in alfalfa roots. These results suggest that NPAAs might be taken up into crop plants from contaminated irrigation water and enter the food chain. This may present an exposure pathway for NPAAs in humans.

Automated summary

The study showed that the growth of alfalfa roots was significantly inhibited by BMAA and DAB, with higher levels detected in the plant. This suggests a potential pathway for NPAAs to enter the food chain through contaminated irrigation water, posing a risk for human exposure.