Symbiotic nitrogen fixers Flashcards
the most important symbiosis known?
The mutualistic relationship between leguminous plants and nitrogen-fixing bacteria
Example of legumes include?
soybeans,clover,alfalfa,beans and peas
Rhizobium?
the best-known nitrogen fixing bacteria engagin in these symbioses
Colonization of legume roots by nitrogen-fixing bacteria leads to?
the formation of root nodules that fix nitrogen
nodule formation nombre de steps?
6
step 1 of nodule formation ?
Recognition and attachment of bacterium to root hairs
Step 2 of nodule formmation ?
Excretion of nod factors by the bacterium
Step 3 of nodule formation?
Bacterial invasion of the root hair
Step 4 of nodule formation ?
Travel to the main root via the infection thread (tube composed of cellulose)
Step 5
Formation of bacteroid state within plant cell
bacteroid
swollen and misshapen bacteria - fix N2
Step 6?
-Continued plant
-bacterial division
forming the mature root nodul
nod factors?
oligosaccharide signaling molecules
why do we need to control oxygen level?
so te nitrogen fixing bacteria can do their job
how is the oxygen level kept in check?
Oxygen levels are controlled by the O2-binding protein leghemoglobin
who produces leghemoglobin?
plant cells
Bacteroids are?
terminal structure and cannot be shed in the environment
but the nodules contains something that CAN inoculate the environment and that is ?
Rhizobium
en gros?
the plant provides organic acids to the bacteroid and in return the bacteroid provides ammonia to make nitrogen containing organic compounds
how is nitrogen fixation in aerial roots in Sierra mixe maize?
through mucilage-associated microbiota
(SMM) can acquire ____ of its nitrogen form the air?
29%-82%
the N is fixed by bcateria in ?
the mucilage
Mucilage?
viscous sugar-rich fluid
secreted by some plants
Mucilage what do u find inside?
- diverse community of bacteria
- Including N fixers ( Rhizobiaceae)
