Is it still considered valid to identify fungal species, specifically Rhizoctonia solani, only microscopically and not molecularly? If so, how do I do microscopical identification?

Question

I am a grade 9 student researcher. I have trouble in this area. Upon reviewing related studies, I found out that most of them identify fungal species molecularly through primers and DNA kits. Unfortunately, our school does not have access to these, and so I will have to identify fungal species microscopically only. Is that valid? Or is molecular identification required? Also, about microscopical identification, I only have limited information about this, the methods, and how it works. I would really appreciate it if someone could enlighten me. Thank you!

Answer 1

Good question! Whatever we do in science, we are doing it with some confidence interval. For example, "how tall you are?". Reasonable answer would be 6 ft 3 inch, so +-1 inch is acceptable error of measurement. When you are presenting the results, you write: Result +- error, or Result and statistical significance. In that way, other people know how precise your measurement was, thus it's not your fault, it's the method.

In your case, you need to identify a specie of an organism known for century(es) and naturally, you are going to use the simplest, the most routine method: observe characteristics and check the tables.

It works... By doing that you can tell what is a tiger and what is a lion.

If you want to go deeper, and use molecular biology - what will be the benefit?

Some genes - you can "see" under a microscope. Their expression actually (genes that cause tigers to have stripes). PCR kits and primers would tell you whether you have some specific sequence. And... Now you have a problem!?

If the primer is not specific enough, you will cover many species, maybe the whole genus. Or if you take some universal, housekeeping genes you will get the information that it's alive, and from Earth :) thus even brother than microscope.

If you want to go really deep, you could design your own primers and identify whatever you want, but it's the equivalent of being tall: 6 ft 3.54657463 inches. Much more precise, but irrelevant information.

By the way, PCR is as old as I am. Prior to the last year, there was no hype about that. Even if you obtain the result using PCR in molecular biology, many times you need to verify it by another method, because PCR = Chemistry. Have similar primers = it will go slower, but will it will go. Rise the temperature = it will go. Wait for a longer time = it will go...

Microscope is a routine method

PCR is also a routine method

Precision is very similar in your case