Original video: https://youtu.be/k_wCM587qGQ
Ever wondered how succulents, cacti, and even orchids thrive in hot, dry environments? This video introduces Crassulacean Acid Metabolism (CAM), a fascinating adaptation that allows these plants to conserve water while still capturing CO2 for photosynthesis.
Video Transcript:
So, the other C is CAM: Crassulacean Acid Metabolism. Not to say that, Crassulacean is actually the name of a family, Crassulaceae, not Crustacean.
So, Crassulacean. So, all these, um, plants that live in rather arid environments. So, you can associate plants that have this CAM mechanism, usually they are fleshy, that's number one, confirm. So, if you say that, oh, that means my orchid is CAM? Yes, orchid is CAM. Only a few are actually, um, C3, yeah. If you go to, uh, admiring your Phalaenopsis, your moth orchids, and you look, oh, this is very fleshy, yes, it is CAM. Maybe you like your aloe vera so much, that is also CAM. Tell me, what else is a fleshy plant? Cactus, yes, cactus. What else? Kalanchoe (Setawar), not star wars. Setawar, it's very fleshy, right?
One thing, super sweet, uh, pineapple, pineapple, yes. Dragon fruit, um, pitahaya. Dragon fruit, you got, sometimes you got red, sometimes you got, uh, greyish, yeah, right? Okay, so, what's the deal with this? If the compartmentalization of C4 is separated physically by two distinct cell types, mesophyll cell and bundle sheath cell, the separation by CAM plants is achieved by what we call as temporal separation, by time. Meaning that, to put it easy, um, if you look at here, time is of the essence here.
During the night, during the day, during the night when the temperature is rather lower, the humidity increases, that's very important, high humidity, and also relatively, um, non-existing intense radiation at night, right? These actually are some of the recipes that can open stomata, yeah? Maybe you just want to open your stomata, but you are growing your plants in the, uh, plant factory, yes, you can do so by having all this condition met.
So, this actually facilitates stomatal opening at night. So, when stomata open at night, um, CO2 will rush in into the cell. And the CAM plants have this mesophyll cell as well, the photosynthetic cell. And the cells here have the regular C3 appearance. You have your chloroplast, you have your vacuole, mitochondria, peroxisome, and so on. However, what's different here is that the CO2 is not going to undergo the Calvin cycle right away. It enters, first gets dissolved to form carbonate, bicarbonate, and then converted to malate, yeah?
So, throughout the night, no sugar precursor formation is happening, it's all about accumulating the reserve of malate, the four-carbon compound. So, CAM, the first product for CAM is also a four-carbon compound, malate, okay? And as the plant is approaching the day, then the light will start to come, right? And it gets warmer. So, when this happens, the stomata will start to close.
When stomata start to close, the malate will undergo decarboxylation, meaning that malate, now with the help of malate dehydrogenase, will release its CO2. Now, malate releases CO2, what does it become now? Pyruvate, yeah. Pyruvate can, uh, do the night job again because this is still a cycle, yeah? So, the CO2 is released and again, the similar thing happens with the C4 plant. Rubisco is being crowded, jammed, bombarded with CO2 presence, no room for oxygen to get in, okay? Pretty much, the Rubisco is deaf or blinded by, uh, the presence of overwhelming CO2, okay? And then the rest of the reaction follows as per usual, uh, Calvin cycle, okay? Then you get your triphosphate and so on.
Keywords: Photosynthesis, CAM, Plant metabolism, Temporal separation
Watch full video: https://youtu.be/ckiJ_go8IaU
Reference book: Plant Physiology and Development 7th Edition
by Lincoln Taiz, Ian Max Møller, Angus Murphy, Eduardo Zeiger
Attribution 4.0 International — CC BY 4.0 - Creative Commons
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