HEURISTIC ASPECT OF THE LATERAL ROOT INITIATION INDEX: A CASE STUDY OF THE ROLE OF NITRIC OXIDE IN ROOT BRANCHING
Por:
Lira-Ruan, V, Mendivil, SN, Dubrovsky, JG
Publicada:
1 oct 2013
Resumen:
Premise of the study: Lateral root (LR) initiation (LRI) is a central
process in root branching. Based on LR and/or LR primordium densities,
it has been shown that nitric oxide (NO) promotes LRI. However, because
NO inhibits primary root growth, we hypothesized that NO may have an
opposite effect if the analysis is performed on a cellular basis. Using
a previously proposed parameter, the LRI index (which measures how many
LRI events take place along a root portion equivalent to the length of a
single file of 100 cortical cells of average length), we addressed this
hypothesis and illustrate here that the LRI index provides a researcher
with a tool to uncover hidden but important information about root
initiation.
Methods and Results: Arabidopsis thaliana roots were treated with an NO
donor (sodium nitroprusside [ SNP]) and/or an NO scavenger
(2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide
[cPTIO]). LRI was analyzed separately in the root portions formed
before and during the treatment. In the latter, SNP caused root growth
inhibition and an increase in the LR density accompanied by a decrease
in LRI index, indicating overall inhibitory outcome of the NO donor on
branching. The inhibitory effect of SNP was reversed by cPTIO, showing
the NO-specific action of SNP on LRI.
Conclusions: Analysis of the LRI index permits the discovery of
otherwise unknown modes of action of a substance on the root system
formation. NO has a dual action on root branching, slightly promoting it
in the root portion formed before the treatment and strongly inhibiting
it in the root portion formed during the treatment.
Filiaciones:
Univ Autonoma Estado Morelos, Fac Ciencias, Lab Fisiol & Desarrollo Vegetal, Cuernavaca 62209, Morelos, Mexico
Univ Nacl Autonoma Mexico, Inst Biotecnol, Dept Biol Mol & Plantas, Cuernavaca 62250, Morelos, Mexico
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