35. Soil
Nitrogen Fixation
Nodules
While some nitrous flying bacteria are content to live in the soil and pass off the fruits of their labor to their fellow plants, some want to take this step further, and we'll actually perform nitrogen fixation inside plant roots. Mostly this occurs in plants of the lagoon Family Lagoon's air flowering plants with the Latin name FIBA, and they carry these rise obeah bacteria in what are called na jewels. In their roots. Now rise obeah are gram negative soil bacteria that perform nitrogen fixation, and they do so in the roots of these legumes. Technically, that makes them end of fights or organisms that live inside other plants. Usually they are fungi or bacteria. Nah, jewels are swollen nodes or lumps in the roots where these bacteria have infected the plants. And make no mistake, even though this relationship is beneficial for both both organisms. This is technically a bacterial infection in the plant, and that's why the swelling occurs. I mean, if you've ever seen a swollen lump in a tree stump or something like that, that's also a site of infection. That's in part how plants will respond to infections. And that is why these swollen lumps look like infections because they are infections. But it's not, you know, unwanted infection. In fact, plants are inviting these bacteria in by releasing these chemicals into the soil called flavonoids. And these actually signal the rise obeah who in turn released their own signal, which are called nod factors. And these nod factors will actually come into contact with the root hairs. So I'm gonna jump out of the image here and just draw right here. So let's pretend here we have Benny Bacteria. Or maybe Rebecca rise obeah. Whatever you wanna think of it, the groups flavonoids will be released by the root hair, and they're gonna make their way to Rebecca. Rise obeah over here, and in turn, she's going to release her, not factors. And that is going to stimulate the root hair and cause a morphological change that will actually allow the bacteria to enter into the cortex the inner part of the plant, through what's called an infection thread. So, basically, Rebecca rise obeah here. I'm just gonna put our our for now she is going thio, uh, take advantage of that morphological change. Enter the root hair, go through the root hair cell and make her way into the cortex. So this is supposed to be cortex sell here. And this, of course, a root hair. So once inside the actual plant cortex, these rise obeah are going to set up shop. You can see an actual image of what this looks like here. All of these dark, uh, lumps are bacteria living in the plant cell, and they're going to get along swimmingly. Actually, they have a mutual ist IC relationship because the plant provides carbohydrates and protection to the bacteria right, and the bacteria is going to provide usable nitrogen. And remember earlier I said that the energy demands of performing nitrogen fixation are very great. But these plants right in this mutual ist IC relationship there helping the bacteria out with those energy demands. They're saying, Hey, look, you're giving us nitrogen. Here's some carbohydrate that you'll be able to convert into a teepee, and then you can use that 80 p to make the nitrogen usable for us. So it's like, you know, you scratch my back, I'll scratch yours Now. In addition, plants will also, uh, are These lagoons will also produce this molecule called leg hemoglobin and hopefully you can pick out that word. Hemoglobin in there. Remember, that is the oxygen binding molecule found in red blood cells. Well, this is like a special kind of hemoglobin. In a sense, this leg hemoglobin, it still binds oxygen. But the reason it's binding this oxygen is actually to protect nitrogenous. That enzyme that's going to carry out, uh, the chemical reaction that turns gaseous nitrogen into ammonia. It's gonna protect that enzyme complex from oxygen poisoning. So it's just one more way in which plants are actually helping out these rise obeah bacteria. Now, I also mentioned that these bacteria weren't the Onley way that plants can obtain nitrogen. And I mentioned to try divorce. And, of course, when you think to try divorce, hopefully you're thinking fun guy. Obviously, bacteria play a role, uh, in the breakdown of organic matter as well, definitely not going to discount how important bacteria are. But these, um, these fungi will form. Remember, my core is I those fungus roots those associations between the fungal hi fi and the plant roots, and in this association they will actually be able thio provide nutrients for the plants like nitrogen and phosphorus both super important, right? Both gonna wind up components of nucleic assets, for example. Now the high fe increase the surface area for absorption. So they're gonna help plants absorb nutrients better. They also, uh, you know, the fungus also will break down organic matter, which is going to free up these elements for absorption. Right? They're gonna help break down structures that they're part of making them easier for plants to absorb. And we're actually going to see two types of micro, is I. There's Ecto Micro is I Which I have pictures of here. And basically, this is micro's I where the haIf a wrap around plant cells but don't actually penetrate into plant cells. So these are not end of fights. Our bus killer Micro is I, on the other hand, are end of fights. They're going to actually penetrate their hi fi into the cortical cells of plant roots. And I don't have a picture of that here. But, you know, you can imagine looking at this image here, for example, that one of these purple haIf A would extend into a plant cell in the Arbus secular micro is I, um, hear what I actually have pictures of our Ecto Micro, is I? So this is a more resumed out image. These brown twiggy looking things are plant roots and all this white gunk all over it. That kind of looks like mold is the is the fungal part of the micro. Is I So you can see, um, you know, with the naked eye basically that close association of plant and fungus. Here we have some mawr zoomed in pictures like right here and especially right here, here. We're looking at, you know, a fungal sheath around the route. And here in this image that's behind my head. You can actually see thehyperfix wrapped around plant cells. These dark spots are going to be the actual cells of the plant and all this white gunk in between them is the high face, so that that's the fungus part of it. So this close association, uh, not only helps plants absorb nutrients but can also help provide some nitrogen phosphorous for plants. And also, don't forget that there's just a bunch of other fungus in the soil free living that's also breaking down organic matter and contributing to the amount of free nitrogen available in the soil. That's all I have for this lesson. I'll see you guys next time
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