I want to establish hairy roots of my plant for abiotic stress treatment, but I want to do it without involvement of Agrobacterium. In every previously done research works, researchers have used the bacterium A. tumefaciens for infection and generation of roots. is there any other simple method which doesnt involve the bacteria?
Hairy root or "crazy roots" disease of vegetables in hydroponic greenhouse production is caused by Agrobacterium and related species with Ri plasmid. Sometimes it is caused by intensive use of plant hormones (IAA-like). Plants transformed with Ri-plasmid can be cured of bacteria by antibiotics, and hairy root phenotype will be fixed for long time. Some plants, like Nicotiana species, can transfer integrated T-DNA by seeds. Somatic propagation of hairy root plants is used for some ornamentals as new breeding technique.
Agro. tumefaciens is used for getting transgenic shoots.
Agro. Rhizogenes strains are used to get those "crazy" roots, growing by themselves with no hormones added.
Either way: if you use one of the Agros you always have to go thru cleaning the shoots or roots thru antibiotics.
Hairy roots have some typical features, like ageotropic growth pattern and heavy proliferation in simple medium mostly lacking growth hormones. We used simple 1/2 strength MS liquid media. These roots are produced through integration of T DNA from A. rhijogenes Ri plasmid. Sometimes a T DNA from A. tumefeciens can be co-transformed. So, these roots are specialized tissues mainly developed for organ culture. Theoretically, hairy roots are not possible without the involvement of rhizogenes. Use of specific phytohormones may induce adventitious roots, but they should not be considered as 'hairy roots'.
I am not sure about your in-vitro system, type of abiotic stress and the plant material, but I am suggesting a way which might help, assuming that you are either using hydroponics or other controlled nutrients based system. Have you tried low Phosphate media!! Phosphate deficiency dramatically inhibits plant's primary root growth and induces proliferation of lateral roots. Once the lateral roots are produced, you can consider transferring the plants back to media containing normal phosphate conc. to tune back the molecular response to normal and then give the treatment. Further, exogenous GA supply also results in more hairy roots.
Article Regulation of root hair density in Arabidopsis by phosphorus...
But he is not asking for root hair density but for hairy roots. Which can go on prospering on their own without plant attached
I am not in depth familiar with the hairy roots phenotype, but my first thought was: if you want to transform Arabidopsis without Agrobaterium, maybe biolistics would be helping?
Now I read, that it is also possible in roots: https://pubmed.ncbi.nlm.nih.gov/11532182/
Your Q is not clear.... A. tumefaciens strains are used for generation of transgenic plants, which takes a lot of time. A. rhizogenes strains are used to generate roots by infecting young leaves or cotyledons (which takes about 30-45 days. If you want to deliver a gene/s to the plants and generate hairy roots for your study you have to choose either of the methods. By using A. tumefaciens you can generate plants and study the root hairs. In case of hairy roots they are not fit for studying stress (the roots themselves). However, you can develop composite plants. You grow seedlings, cut and remove the lower part of the stem and root, infect the stem (hypocotyl) with with appropriate A. rhizogenes strain/s. For in vitro plants grow the infected explant only with antibiotics that kill the agro. Don't use Kanamycin since the whole part could die. Transgenic roots will develop from the stem and your plant will have non-transgenic shoots and transgenic roots. Such plants can be grown in soil will fit for your study. Alternatively, bark of some plants (seedlings are removed and suspension of A. rhizogenes will be applied around the wound, cover with soil and wait until hairy roots emerge. You can cut the rooted part that has new hairy roots and transfer it to new media for your stdy.
Google about: "Composite plants" AND"A. rhizogenes"
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