Nitric oxide signaling and cysteine protease activity in the modulation of abiotic stress responses in soybean and maize
Date
2010-11-24
Authors
Bilibana, Mawethu Pascoe
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
ABSTRACT: Nitric Oxide (NO) is an essential bioregulatory molecule in plant growth, development,
and tolerance against biotic and abiotic stresses. In legume root nodules, abiotic stresses
impose restraint on metabolic capacity of bacteria and cause oxidative damage to cellular
macromolecules, leading to inhibition of nitrogenase activity. In this study, the primary
aim was to determine the influence of NO signaling on cysteine protease activity in
soybean (Glycine. max [L] Merr) root nodules. Intact plants were treated with a NO
donor, diethylenetriamine/nitric oxide adjunct (DETA/NO), 8-(4-chlorophenylthio)-[CPT]-
cGMP, sorbitol and sodium chloride (NaCl). The root nodule cysteine protease activity
was measured using the chromogenic substrate N-benzoil-L-p-nitroanilide (L-BAPNA).
The results demonstrated NO as acting both as a protection against programmed cell
death (PCD) at low exogenously applied NO concentrations, or as inducing PCD through
regulating the cysteine proteases activity in root nodules when NO is applied at elevated
concentrations. In the root nodules, the activity of cysteine protease is regulated either
through cyclic guanosine monophosphate (cGMP)-dependent during abiotic stress or
cGMP-independent pathways during normal root nodule development. The purpose of
this research was to highlight the importance of NO in cell signaling and cysteine
protease activity in legume root nodules. We also focused on the effect of abiotic stress
on two maize genotypes as well as the influence of abiotic stress on cysteine protease
activity in the abiotic stress-sensitive maize genotype than the tolerant genotype. The
study suggests that cysteine protease activity can be used as early screen to identify
abiotic stress-sensitive/tolerant maize genotype upon exposure to abiotic stress.
AFRIKAANSE OPSOMMING: Geen Afrikaanse opsomming beskikbaar.
AFRIKAANSE OPSOMMING: Geen Afrikaanse opsomming beskikbaar.
Description
Thesis (MSc (Plant Biotechnology))--University of Stellenbosch, 2010.
Keywords
Soybean, Maize, Cysteine protease, Nitric oxide signaling, Dissertations -- Plant biotechnology, Theses -- Plant biotechnology, Corn, Abiotic stress