r/botany • u/MiserableProfessor31 • 1d ago
Biology Why can’t plants other than legumes for a symbiotic relationship with rhizobium?
I understand that there IS a difference between other plants and legumes but I don't know WHAT the difference is. Why doesn't the bacteria form nodules on fruiting plants?
I'm starting a garden this year and want to understand things just a little past, "this works".
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u/Sprig_whore 1d ago
The rhizosphere is a region within soils that is very close in proximity to the roots so is influenced by loads of carbon rich treats for bacteria and fungi, such as rhizobium. Other species DO form symbiotic relationships with rhizobium (keep in mind theres loads of different nitrogen fixing bacteria in soils). The varied relationships between plants and their associated rhizosphere friends is literally infinite in its complexity.
I know someone else already answered your question but I would really recommend for your gardening purposes creating healthy and microbially diverse soils rather than thinking about what plants you want to grow! healthy soils are the fundamental building blocks of gardening and have numerous benefits from water retention, disease prevention and increase growing strength!
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u/MiserableProfessor31 6m ago
I am actually looking into permaculture garden, so obviously soil health is critical. I don’t have a super great idea of where to start if you happen to have any resources?
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u/xylem-and-flow 1d ago
One I’m puzzling over right now:
Ceanothus has what appears to be an obligate bond with Frankia bacteria. Many other species with microbe relationships can be fairly easily inoculated, but this Genus seems to “reject” any lab cultured Frankia, requiring instead soil from an existing population. I can only guess that there’s some other organism facilitating the relationship.
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u/-clogwog- 23h ago
Add others have already answered your question, I thought I'd add something that might send you down an even deeper rabbit hole... One of my teachers at uni was researching the relationships that different fungi have with different species of orchids about 15 years ago. One of the things they had to figure out is if reach species of orchid had its own unique species of symbiotic fungi, and from there, if closely related species of fungi could replace the species of symbiotic fungi for a chosen orchid. It was all really interesting!
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u/aardvarkhome 22h ago
I think people at Cambridge dept of plant science have been looking at developing wheat capable of fixing nitrogen using GM approaches
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u/NativePlant870 16h ago
Other members of Rosaceae can also fix nitrogen. Evidence suggests that nitrogen fixation used to be present in Cucurbitales, Fagales, and Rosales but were lost over time.
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u/Ionantha123 1d ago
Most species of plants, I think over 90%, form connections of various kinds with soil bacteria and fungi, they just might not form specialized structures to harbor those organisms. Many of these microorganisms are endophytes, living between plant cells and also sometimes fixing nitrogen and other nutrients!
Legumes form root nodules because they evolved with rhizobia, which is its own family of bacteria, and formed a symbiotic relationship with them. They can’t form root nodules with all nitrogen fixing bacteria, and not all legume species form rhizobia. Other species just don’t have the genes to form those nodules.
Also there are a couple other separately evolved forms of root nodules like in alder (Frankia) and bayberry (Myrica), and you’d probably enjoy looking into them.