Chemical priming of stress signalling pathways for enhanced stress tolerance in plants

ANU researchers have developed a novel method to regulate key plant stress responses such as stomatal closure using an agrochemical strategy.

Background

The enzyme SAL1 (adenosine 3'-phosphatase) regulates levels of a drought-inducible chloroplast-to-nucleus stress signal, 3'-phosphoadenosine 5'-phosphate (PAP). Accumulation of PAP in Arabidopsis SAL1 loss-of-function mutants enables enhanced survival up to 50% longer than the wild type plants under water deficient conditions. Researchers from ANU have also showed that PAP naturally accumulates in wild type plants during drought stress, and discovered that PAP can induce closure of stomata when accumulated in plants or when applied as an agrochemical. When applied to leaves, PAP can induce similar signaling networks as those activated by the key plant stress hormone, abscisic acid (ABA). Significantly, PAP controls stomata in all land plants tested.

Researchers at ANU have been investigating how activity of the SAL1 enzyme can be controlled to enhance drought tolerance. Their recent breakthroughs using targeted biochemistry and drug screening approaches have shown that activity of SAL is critical to the control of PAP levels. Importantly, the ability of SAL1 to degrade PAP in plants can be controlled by foliar application of novel (agro)chemical inhibitors. Collectively, these findings indicate the potential to prime stress tolerance in plants using designer chemicals which decrease SAL1 activity, leading to PAP accumulation and stomatal closure.

Technology

A research group at ANU have identified first-generation lead compounds capable of inhibiting SAL1 when sprayed onto plants and thereby conferring drought tolerance.  This SAL1-PAP chemical inhibitor system is a potentially superior agrochemical approach in engineering drought tolerance since it does not rely on a GM approach, in contrast to other recently published agrochemical strategies such as those involving the drought hormone ABA.

Benefits:

  • Technology to improve drought tolerance in both monocot and dicot crop plants
  • Delivery via non-GM approaches possible
  • SAL1 crystal structure and inhibitor structure allows rational design of additional chemical inhibitors
  • SAL1 activity, PAP accumulation and drought tolerance can be manipulated via controlled application of designer bioactive chemicals.
  • A one-off foliar application is sufficient to confer drought tolerance (for Arabidopsis: 0.4 nanograms inhibitor per plant)
  • Chemical synthesis platform already established and can be scaled up for industrial synthesis (at lab scale: $6 per miligram of inhibitor; or $2.40 per 1 million Arabidopsis plants)
  • Chemical synthesis platform opens up "chemical space" to include novel and designer compounds that are unavailable commercially, thereby enhancing desired properties and protecting IP.

Opportunity

ANU is seeking collaborations with agrobiotechnology and seed companies with interests in improving drought tolerance in crop plants.

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