Monitoring Nutrient Stress In Plants Using Protein Biomarkers and ELISA

Mineral nutrient stress (deficiency or toxicity) is widespread in horticultural crops, and the negative economic impact of this nutrient stress is substantial.  There is a pressing need to develop additional methods to detect incipient nutrient stress (prior to visible symptoms), to mitigate crop damage, or to identify the specific nutrient stressor.  To this end, we have initiated a long-term project to develop a suite of ELISA-based diagnostic assays for several commonly-problematic nutrients.  A bioinformatics approach is used to identify appropriate conserved domains in specific important nutrient transport proteins, and then short peptides of these domains are used to generate polyclonal antibodies specific to each protein.  Antibodies are antigen-purified if needed, and antibody specificity is checked by western blotting.  ELISA assays are optimized and their sensitivity determined using plants grown over a range of nutrient levels; purified antigen is used to calibrate each ELISA.  We have generated an ELISA assay for the boron transport protein, BOR1, and are currently developing assays to P, Fe, N, and Cu transport proteins.  BOR1 results confirm the utility of the ELISA approach and of using BOR1 as a biomarker for boron stress.  These ELISA-based assays will supplement other available tools for detecting and evaluating plant nutrient stress, and in some ways will offer distinct advantages over current methods.