Crop Protection

Crop Protection

Crop protection is the single most important challenge facing terrestrial agriculture, and a lack of crop protection is now being recognized as the chief limiting factor in algal biofuels production. Algae crop protection includes combating pathogens (viruses, bacteria and fungi), predators (protozoa, planktonic crustaceans, rotifers and helminths), weeds (undesired algae and water plants), and high-density growth inhibitors produced by algae or associated bacteria. CAB-Comm was tasked with researching all aspects of crop protection, from identifying the basic pathogenic microorganisms to identifying strategies and molecules that allow for crop protection in algal production facilities.

Objectives

  1. Characterize algal genetic resistance to chytrid fungi
  2. Examine crop protection by secretion of extracellular products and their potential roles in suppressing growth of competing species
  3. Develop anti-viral technologies
  4. Identify and characterize quorum sensing molecules (QSMs) from algae that act as high-density growth inhibitors
  5. Produce antimicrobials for crop protection in eukaryotic algae
  6. Develop strategies for finding or constructing grazer/competitor resistant strains

Accomplishments and Discoveries

amoebe grazing

A cyanobacteria mutant with O-antigen production impairment shows resistance to a grazing amoeba

Researchers characterized algal genetic resistance to chytrid fungi and identified a stress response pathway. They examined a variety of environments, including freshwater and brackish natural ponds, as well as experimental freshwater and marine outdoor production ponds, and used grazers to establish model systems to uncover cyanobacterial resistance mechanisms and in doing so identified 10 genes involved in lipopolysaccharide (LPS) synthesis. Mutations in these genes confer resistance to grazing by an amoeba in a unicellular strain.

Other researchers examined chlorovirus-algae interaction. They isolated virus-resistant algae mutants, to which the viruses could not physically attach. The researchers also tested and found support for a hypothesis that some algae exhibited innate immune responses to virus infection by encoding and utilizing RNA silencing mechanisms to suppress virus replication.

In the research project examining antimicrobial production, researchers discovered that the algae C. reinhardtii have native synthases (phosphopantetheinyl transferases) which are necessary for two synthases (non-ribosomal peptide synthase and polyketide synthase) that produce antibiotic molecules for crop protection. Researchers attempted to engineer the antibiotic-producing synthases into C. reinhardtii, but had mixed results.

Examining algae polycultures, researchers discovered that predators are far more damaging to monocultures than they are communities consisting of 5-10 algal species. These important advances have laid the foundation for the elucidation and practical application of algal defense strategies and pathways. 

Publications