Additionally, if anyone ever has any general questions about agricultural biotechnology and how it may be applied in your own endeavors, I would be more than happy to do that. There are a lot of cool and cutting-edge technologies being developed to prevent and/or treat pest, disease, drought, and many other issues growers contend with.
Can you give a brief intro or overview as to the types of technologies you are talking about, sounds interesting.
Absolutely! What we refer to as biopesticides in the agricultural biotech space can generally come in three forms: biochemicals/biologicals, microbials, and transgenic. There is also fourth type emerging, using RNA-interference technology, which I will also summarize.
(Please note I have included some links for reference, in blue)
Biochemicals/Biologicals
These consist of a compound or protein that are produced by plants or microbes. Some examples of biochemicals include
capsaicin (which you may be familiar with from various peppers) to protect against insect pests, and
macrocidin, which is a compound produced by a fungus called
Phoma macrostoma that exhibits herbicidal properties towards broadleaf weeds. Biologicals may be broadly defined as proteins or peptides that exhibit antagonistic activity towards pests. In this category, perhaps none is more common than the
Cry protein which is produced by a bacterium called
Bacillus thuringiensis and protects against pests such as nematodes. To summarize, this category of biopesticide is comprised of products naturally produced by organisms and concentrated in a solution that can be applied to crops for protection against various pests.
Microbials
This category of biopesticide is comprised of a spray or solution that literally contains living or suspended (spores) microbes. The microbes used in these sprays are comprised of "good" bacteria that exhibit antagonistic properties against various pests. These may often be spore-forming bacteria, which have been generally observed to exhibit pesticidal properties.
Some of the most common comprise
Bacillus thuringiensis,
Pseudomonas, and
Trichoderma species which each exhibit pesticidal activity towards different kinds of pests. Bt spray is a great example of this, which is generally composed of
B. thurigiensis spores which contain the pesticidal Cry protein. Additionally, microbes can be applied for other beneficial properties such as nitrogen fixation to assist with nutrient uptake, serving as a probiotic for plants much in the same way we take probiotics for our gut health. Microbial biopesticides are an active area of investigation in the agricultural biotech space due to the ubiquity of plant-friendly bacteria, ease of production, efficacy, and sustainability.
Transgenic
This category of biopesticide is not a spray or application, but rather genetic modification of a crop to confer pesticidal properties. A foreign gene (transgene) for a pesticidal protein from another organism such as a bacterium or plant, is engineered into the genome of a crop in order to confer those pesticidal properties into the plant. The best example of this is
Bt corn. The bacterium
Bacillus thuringiensis contains genes that give it insecticidal properties. By transposing these genes from the bacteria into the genome of corn, an insect-resistant strain of corn could be generated. Since the creation of Bt corn, it has grown to be the
dominant strain of corn grown in the United States. This approach has been utilized in a number of other crops and plants to confer resistance to pests as well as improve qualities such as drought tolerance and
taste. I know this can be a very divisive topic so I am not here to condone or condemn genetically-modified crops, but rather explain how they work at a high level. Ultimately, this kind of protection is conferred via genetic engineering.
Bonus: RNA Interference (RNAi)
This is a very new technology that shows promising applications in the area of crop protection. To understand how this technology works, we just need a brief refresher on molecular biology, so please forgive me if you already know this. All organisms have DNA which contains the genetic code for every protein that an organism produces. However, to make a protein from this genetic code, we go through a two-step process: 1) A specific part of the DNA, which encodes a specific protein, is "copied" into a molecule called
single-stranded RNA; 2) This copy of the sequence, called RNA, is then "translated" into a specific sequence of amino acids. This sequence of amino acids makes up a protein. And so we have generated a single protein from a code within the DNA. To summarize, we go from DNA->RNA->Protein.
RNA interference is a molecular mechanism that is found in almost every organism, humans included. It is a protection mechanism against viruses, similar to the immune system. A common way for viruses to attack a host is by injecting
double-stranded RNA into its host in order to use the host's genetic machinery to replicate the virus. However, many organisms evolved a defense mechanism called RNA interference in which this
double-stranded RNA is recognized, isolated, and degraded to prevent the replication of the viral RNA. The key point here is that RNA, which is needed to make a protein, is degraded, and as a result, no protein can be made, which means no replication of viral protein. Just like the name implies, this mechanism interferes at the RNA level.
While this defense mechanism is great for protection against viral RNA, it also can induce silencing of the host's own genes. Scientists learned that if you introduce double-stranded RNA that exactly matches a sequence within a an organism's own genetic code, that sequence can be "silenced". This was famously observed in
a study of pigment expression in petunias. The researchers in this study thought they could induce higher expression of pigment in petunias by introducing
double-stranded RNA for the sequence that encodes the pigment protein. Unbeknownst to the researchers, they triggered the RNA interference mechanism in the petunias by using
double-stranded RNA and ended up with white, rather than purple petunias! Up to this point, the mechanism of RNA interference was unknown and so these researchers were baffled by these results. In the years since, we have come to learn about the RNA interference mechanism in plants, fungi, insects, and mammalian systems, though we have barely scratched the surface. RNA interference may be favored over other genetic engineering techniques because it does not actually alter the genetic code. Rather, it stops the expression of a specific protein at the RNA level. This mechanism can be induced temporarily, or permanently depending on your goals.
Now, how does this apply to crop protection? Scientists can very easily make double-stranded RNA in the lab, and it can very easily be put into a spray that can be applied to plants. This double-stranded RNA can be tailored to specifically target gene sequences of pests. Remember, the sequence has to be an
exact match to the target sequence, or it won't work. This makes it harmless to other organisms, plant included. This is what makes RNA interference applications so promising in the field of crop protection. One company,
Greenlight Biosciences, is developing the first of its kind biopesticide using RNA interference technology to target the Colorado Potato Beetle. When the spray is applied, the beetle ingests the double-stranded RNA which targets a critical protein in the beetle. It has been shown to be effective in killing the beetle while remaining harmless to other organisms, including bees and butterflies. I believe this specific biopesticide is due to be approved this year, and I think there will be a lot of eyes on it to see how it ultimately pans out.
This was a very high-level overview of the technology that is being actively applied and investigated in the field of crop protection, and there may be others that I have missed. There is certainly a lot of nuance to these discussions and I could not address every single bit of it for the sake of time. However, I hope this was helpful and maybe sparked some interest in how you can apply some of these technologies in protecting your plants and crops!
