Internode Inhibition

Martin Hughes hughes at
Fri Feb 12 02:22:53 EST 1993

>ajt at (Tony Travis) writes:

>>WHITSON, JOHN LEE (jlw2582 at edu.tamu.rigel) wrote:
>>: Does anyone know of an internode-length reducer that i can get my hands
>>: on?  i've been told that Gibberelic acid inhibitors work quite nicely,
>>: but everyone (outside of the Hort dept at Texas A&M) that i've asked has
>>: met my question with a blank stare.
>>: Any ideas?

>How about Blue light ;-)

Well, after having "lurked" on this group since its inception, I
finally feel confident enough to comment on something - and
what is more to the point, in direct reply to something by the
Great Tony!!!

Firstly, to answer the guys question.  Yes, GA biosynthesis inhibitors
will work to decrease internode expansion.  Uniconazole or
Paclobutrazol will do the job for you.  (Uniconazole is from a
Japanese company-Sumi7 (a branch of Sumitomo - ICI sells
 Paclobutrazol, maybe under adifferent name).  Can be applied 
by spray, to the roots, or to seeds (with germinated radicles). Seeds
 can be soaked for 1h in1mM (Uniconazole), followed by washing
for 1h in water.  For further info (esp. for Paclobutrazol) see Plant
Physiol. (1992) 100: 651-654.

And, as Tony said so will blue light.

And this, I think is the interesting point.  Several other things will
also inhibit internode expansion.  Recently Frances et al. (Plant Cell
4: 1519-1530) noted the similar photomorphogenic phenotypes
of their light-independant developing pea mutant with previously
reported heat-shocked seedlings - in that both had (amongst
their characteristics) reduced internodes.  Additionally, leaves 
underwent development.  So, the question is, are all these causes
(GA inhibitors, phytochrome transduction pathways and heat
shock treatments) inter-related (and if so, to what level), or
do they all serve to "trigger" the same (series of) responses
in a trivial manner (after all, there are a limited number of things
a plant can do in response to a stimulus!)?  Any thoughts?

>        Tony.
Martin Hughes
Lab. Photoperception & Signal Transduction: Frontier Research:

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