Biocontrol buddies

Obviously biocontrol is super important to agriculture. There are several methods for controlling pathogens and some of them are fungi.
One such fungus is Clonostachys rosea, which is a mycoparasite of several pathogens that live in the soil. It not only directly parasitises soil pathogens, but also competes for root colonization with, thus indirectly controlling pathogen access to crops.

Clonostachys rosea colonies on plate

As mentioned in a previous post, working multiple methods synergistically is a great way to maximize the effectiveness of overall treatment. There are however, some major downsides to this. One of the biggies is finding those that work well together.
Enter into today's equation, Pseudomonas chlororaphis. P. chlororaphis does a great job protecting crops from both seed and soil-borne pathogens by increasing plant systemic resistances of the plant as well as competing for nutrients and secreting antibiotic molecules. That last one there, the antibiotic substance (in this case the polyketide 2,3-deepoxy-2,3-didehydrrhizoxin) is the problem with combining P. chlororaphis with other methods. Specifically, 2,3-deepoxy-2,3-dide... let's just call it DDR. Anyways, DDR is an essential antifungal produced by P. chlororaphis  and as such it doesn't always play nice with the fungi we actually WANT on the crop.
This brings us back to C. rosea. This fungi has previously demonstrated that it can hold its own against some antifungal treatments, as well as inhibiting crop pathogens in a different manner than P. chlororaphis (Which is important as having two control mechanisms doing the same thing would be redundant.)
Now a graduate student at the Swedish University of Agricultural Sciences has analyzed and researched the potential of hooking these two up.

Gene expression of ABC-transporters in the fungal biocontrol agent Clonostachys rosea in response to anti-fungal metabolites from Pseudomonas chlororaphis

Jinhui Wang has looked at the production ABC transporter proteins in C. rosea and how they respond in the presence of DDR. ABC transporter proteins are basically the first line of defense against anti-fungals by translocating toxins out of the cell.
So the objective of the study was to see whether C. rosea could handle the toxins made by P. chlororaphis and then check the gene expression of ABC Transporters.
This was done by measuring biomass differences and growth rates in cultures when exposed to P. chlororaphis and its metabolites, and  then use quantitative PCR to determine the expression of 13 ABC transporter genes in C. rosea.
While biomass decreased and some of the transporter genes were induced from the P. chlororaphis, the overall decrease was slight enough that it was determined that C. rosea could potentially be a tolerant roommate for P. chlororaphis. The study did conclude that understanding the ABC transporter interactions would be necessary to really see how these two crazy kids would get along.
But once again, the future of pest control relies on finding methods that work together with one another to accomplish our Agricultural goals. And once again a fungus rises up to the challenge.



Study: Wang, Jinhui, 2012.Gene expression of ABC-transporters in the fungal biocontrol agent Clonostachys rosea in response to anti-fungal metabolites from Pseudomonas chlororaphis . Second cycle, A1E. Uppsala: SLU, Dept. of Forest Mycology and Pathology 

picture: http://www.tamagawa.ac.jp/sisetu/gakujutu/alsrc/tama_kin/slide08E.htm