No Adeventitious Roots!

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

William E Williams - 24 Feb 2006 14:55 GMT

Dear Plant-Eders,

We've been doing a mung-bean adventitious-root experiment for years
now in our first-year biology course, and this year for the first
time we have NO adventitious roots, even in the water control
(usually it develops a few very long adventitious roots, quite
according to Hoyle. Or perhaps Went.). We do see some plant death in
the highest auxin concentrations (we usually do, so this suggests
that our auxin is active), but not one single jar has even a hint of
an adventitious root.

Suggestions? Only thing I can think of is that there's something
peculiar with the water -- we did have an E. coli alarm a few weeks
ago and so they spiked our well with chlorine, but we used RO water
with a substantial charcoal filter on the end of the RO machine,
which should have removed most of the chlorine.

We're stumped. I thought I remembered a posting here a while ago
about some plant species that had had auxin response bred out of
them, but I couldn't find it in the archives; are maybe the newest
mung-bean seeds are not auxin responsive? But then, why wouldn't we
have roots on the control?

-W2

William E. Williams <mailto:WEWilliams@smcm.edu>
Professor of Biology
Saint Mary's College of Maryland
18952 E Fisher Rd, Saint Marys City, MD 20686
(240)895-4365

Reply to this Message

David R. Hershey - 25 Feb 2006 01:44 GMT

When I was an undergraduate, our plant propagation course experiment on
rooting of mung bean cuttings failed and was blamed on bacterial
contamination of the distilled water supply.

Did you root the mung bean cuttings in plain distilled water?
Researchers using the mung bean hypocotyl cutting rooting system
sometimes use a complete nutrient solution (Dhindsa et al. 1987)
because roots require boron and calcium in the external solution for
normal functioning. Epstein (1972) noted that

"for many years it was not realized that even brief exposure of plant
tissue to solutions lacking calcium will cause injury..."

Bohnsack (1991) has a nice teaching lab that shows retardation of
squash root elongation three hours after being placed in minus boron
solutions.

Houseplant cuttings might be a more practical choice to show that auxin
promotes adventitious root formation. Mung bean seedlings are not
rooted commercially but coleus, chrysanthemum, poinsettia and many
houseplant cuttings are routinely treated with auxin to promote
rooting. An advantage of using an ornamental plant is that students can
take the plants home after the experiment. Ross Koning (1994) has a
student lab using houseplant cuttings and three commercial rooting
powders.

References

Bohnsack, Charles W. 1991. Investigating the boron requirement of
plants. American Biology Teacher 53: 486-488.

Dhindsa, Rajinder S., Dong, Guangyuan and Lalonde, Louis. 1987. Altered
gene expression during auxin-induced root development from excised mung
bean seedlings.
Plant Physiology 84(4): 1148-1153.
http://www.pubmedcentral.nih.gov/pagerender.fcgi?artid=1056743&pageindex=1

Epstein, E. 1972. Mineral nutrition of plants: Principles and
perspectives. New York: Wiley.

Koning, Ross E. 1994. Vegetative Propagation. Plant Physiology
Information Website.
http://plantphys.info/Plants_Human/labpdf/vegprop.pdf

Plieth, Christoph. 2005. Calcium: Just another regulator in the
machinery of life? Annals of Botany 96 :1-8.
http://aob.oxfordjournals.org/cgi/content/full/96/1/1

White, Philip J. and Broadly, Martin R. 2003. Calcium in plants. Annals
of Botany 92: 487-511
http://aob.oxfordjournals.org/cgi/content/full/92/4/487

Reply to this Message

Natural Science Forum / Biology / Botany / February 2006

No Adeventitious Roots!