Insights into plant immunity

Plants acquire broad spectrum disease protection from β-aminobutyric acid (BABA), research has found.

The collaborative research, led by researchers at the University of Sheffield in the UK and including scientists from the University of Western Australia, identified the enzyme, an aspartyl tRNA synthetase designated IBI1, as the key receptor that binds BABA.

“This class of enzymes play a vital role in primary metabolism of all cells, but had never been linked to immune responses in plants. Binding of the chemical to this protein triggers a secondary function that ‘primes’ the plant immune system against future attacks by pests and diseases,” said Dr Estrella Luna from the University of Sheffield.

BABA has long been known for its protective effects against devastating plant diseases, such as potato blight, but has not widely been used in crop protection because of undesirable side effects - it suppresses plant growth when applied in high doses.

The researchers found that BABA-activated IBI1 controls plant immunity and growth via separate pathways.

“Importantly, our study also revealed that the undesirable side effect of this vaccination, a reduction in growth, can be uncoupled from the beneficial immune reaction,” said Dr Oliver Berkowitz from the ARC Centre for Excellence in Plant Energy Biology and the School of Plant Biology at UWA.

“Since plant immunisation by BABA is long-lasting, primed crops would require fewer applications of fungicides, thereby increasing sustainability of crop protection. Furthermore, immune priming boosts so-called ‘multi-genic’ resistance in plants. Plant immunity that is controlled by a single resistance gene, on which most conventional breeding programs are based, is comparably easy to overcome by a pathogen. By contrast, priming of multi-genic immunity by BABA is difficult to break, thus offering more durable crop protection,” said the study leader Dr Jurriaan Ton.

Although their research was conducted on the mustard plant, Arabidopsis thaliana, the researchers are confident the findings will be transferable to crop plants. Indeed, proof-of-concept experiments have already shown that BABA is perceived in a mechanistically similar manner by tomato