Selecting for Nitrogen Fixing Roots in Corn / Maize

[Juliadakin1]

We could consider this differently-- instead of selecting for plants with air roots, some may be better than others at fixing nitrogen by hosting colonies of bacteria on their leaves (see the video below with explanation).  In neither case do we actually understand what's going on   Maybe the air roots are the visible markers of plants that have more efficient colonies of bacteria on their leaves-- but the bacteria on the air roots isn't actually pulling the heavy load. In any case, the giant Mexican maize plants associated with this gel and air roots are also much hairier. For everyone aiming to notice these on your plants this year, also check out the stem and leaf fuzz and see if there's a correlation!  And height. Do more giant plants  with more leaves and a lower cod/leaf ratio do better in poor soils? And I'd love to hear about it.


Dr James White talks new research showing how nitrogen fixing bacteria also lives on leaves: 
https://youtu.be/VHs_zNdmfcM

[Cotyledon]

If the bacteria is found on some roots, and is passed vertically then some roots bearing it are likely to make contact with the soil, particularly when old traditional deeper planting methods are employed and the microbial colonies involved might be able to grow larger in contact with soil.

It's not uncommon for an endophytic organism to become increasingly established in the area of the roots over time.

The presence of increased hair was suggested by one paper I recently read to indicate the presence of Teosinte genes, likewise I read that increased red and purple pigments also correspond to similar introgressions of allele sets from Teosinte. This would suggest that this trait is not recently arrived at and that the endophytes in question may have been present in ancestral populations before the domestication of maize.

Many endophytes can be isolated from leaves of plants, sometimes dozens of organisms are present from several kingdoms of life. A lot of this is like with our own species, where each of us carries countless organisms on and in us. Plants tend to be really good about hosting and passing along their own sets of microbial partners as well as infections, so the organisms present in the actual seeds are often more interesting than those that can be isolated from leaves, as that many of the latter can be picked up from the environment and are not passed down by the mother plant to the seeds.

The question is, when this corn is treated with antibiotics that remove the bacterial endophytes completely, how are growth rates and yields affected?

In many species endophytes grown on leaves cost the plant energy and the plants grow better without them, but clearly if N fixation is happening then plants will grow better with the endophytes. 

[AndrewB]