Dear Readers!
A long time has elapsed since the last post. A lot had happened in the meantime, but now, I would like to present a summary of my results in the topic of ROP-NO interactions.
My experiments were supported by the New Excellence Program of the Ministry of Human Capacities.
The summary of my main observations:
Nitric oxide (NO) is a gaseous signal molecule which in cooperation
with auxin regulates root developmental processes like primary root or root
hair elongation and lateral root formation. Some of these physiological
processes take place with the participation of plant-specific regulator Rho of
Plants (ROP) proteins which are known to interact with auxin. ROPs act
as molecular switches due to conformational changes upon GTP binding and
hydrolysis facilitating transient interactions with effector proteins. Although,
NO and ROPs as regulators share common interacting partner (auxin) and
physiological process (root growth), their crosstalk has not been proven so far.
My study aims therefore to examine a suspected ROPs-NO signal interplay in
plants. I developed an experimental system, in which the NO sensing of different
ROP mutant and reporter Arabidopsis
lines were evaluated.
Compared to the wild-type (Col-0), rop2-1 and rop2-2 roots
showed significant NO insensitivity, while rop6
responded to the presence of NO donors similarly to Col-0 (NO-induced root meristem shortening). In agreement with
this, neither the rate nor the pattern of ROP6 in situ expression was affected by NO supplementation. The in situ expression of ROP2; however,
decreased in the presence of NO, as well as the PIN-dependent auxin transport
and auxin maximum in the root tip. Moreover, both rop2 mutants possess elevated endogenous NO level in their root tip
compared to Col-0, which further
support the connection between NO and ROP2 signalling the root meristem.
Based on the results we can strongly suspect
that exogenous NO negatively influences ROP2 action thus inhibits polar auxin transport
and consequently the generation of auxin maximum leading to root meristem
shortening. To confirm this conclusion, my further experiments will focus on
providing direct evidence for the involvement of ROP2 in NO-induced root
meristem shortening.
The effect of
S-nitrosoglutathione (250 uM GSNO, NO donor) on PIN1::GFP expression in Arabidopsis primary root tips. Bars= 50
µm. n=10±SE, **P≤0.01, Student t-test.
Acknowledgements: this
work
was
Supported by the unkp-17- 4 new national
excellence program of the ministry of human capacities.
