Functional Redundancies in Cyanide Tolerance Provided by β-Cyanoalanine Pathway Genes inArabidopsis thaliana

Abstract

Premise of research. The β-cyanoalanine pathway is the primary mechanism for detoxification and assimilation of excess cyanide in higher plants. Two genes (AtCysA1 and AtCysC1) mediate the first step of the pathway, and a single gene (AtNit4) mediates the second step. The potential functional redundancy between the enzymes encoded by AtCysA1 or AtCysC1 was examined with knockdown lines for each gene to determine the extent to which cyanide tolerance was altered. A knockdown line for AtNit4 was also examined for alterations in cyanide tolerance and to infer whether activity of the sulfurtransferase pathway can compensate to provide cyanide homeostasis and detoxification if the β-cyanoalanine pathway is disrupted.Methodology. Arabidopsis thaliana (Col-0) and single SALK line knockdown mutants for β-cyanoalanine pathway genes were germinated on Murashige and Skoog medium in plates and grown in hydroponics to accumulate sufficient biomass. Plants were exposed to chronic or acute doses of cyanide, and physiolo...