Triticeae Genomics and Genetics 2016, Vol.7, No.3, 1
-
9
1
ResearchReport
Open
Access
The Physiological Role of Proline and Sodium as Osmotic Stress Signal
Components of Some Crop Plants
Hamdia M. Abd El-Samad
Botany Department, Faculty of Science, Minia University, El-Minia, Egypt
Corresponding
author
email:
Triticeae Genomics and Genetics,
2016,
Vol.7,
No.3
doi
Received: 17 Mar., 2016
Accepted: 03 May, 2016
Published: 12 May, 2016
Copyright
© 2016 Hamdia, This
is
an
open
access
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terms
of
the Creative Commons Attribution
License, which
permits
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use,
distribution,
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reproduction
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any
medium,
provided
the
original
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is
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Preferred
citation
for
this
article:
Hamdia M.A.E.S , 2016, The Physiological Role of Proline and Sodium as Osmotic Stress Signal Components of Some Crop Plants, Triticeae Genomics and
Genetics,
7(3):
1
-
9 (doi
)
Abstract
The increase of Na
+
and proline content in maize, wheat, broad bean, cotton and parsley plants indicated that the proline
content may act as an indicator of Na
+
uptake and allow the identification of tolerant plants, which effectively exclude Na
+
from plant
either by exclusion or compartmentalization. In maize and cotton plants while Na
+
increased in shoots and roots, proline content
decreased in these organs of these plants. This concomitant with reduction of dry matter of both organs of the maize and cotton plants.
Sodium can be considered as osmotic stress marker component in these plants, especially in shoots of cotton. The percent
accumulation of proline in both organs of wheat and parsley plants, shoots of broad bean run parallel with the reduction in dry matter
of these plants. This strategy of proline and dry matter was concomitant with the increase of Na
+
content of these plants.
Pytohormonal treatment with either GA
3
or Kinetin 200 ppm was mostly decreased the accumulation of both osmotic stress markers
(sodium and proline) at all levels of salinity in shoots and roots of maize, wheat, cotton, broad bean and parsley plants.
Phytohormonal application was significant reduced mostly the accumulation both stress markers sodium ion and proline in shoots
and roots of maize, wheat, cotton, broad bean and parsley plants. This can be reflected on the accumulation of metabolities which
finally affected on the production of dry matter in shoots and roots of the five tested plants.
Keywords
Salinity; Sodium; Proline; Tolerance; Sensitive; Phytohormonal application
Introduction
Salt stress is one of the major abiotic stress factors that affect almost every aspect of physiology and biochemistry
of a plant, resulting in a reduction in its yield (Foolad, 2004; Tatar et al., 2010; Babu et al., 2012, Hamdia and
Shaddad, 2010, 2014 and 2016). Thus it is a serious threat to agricultural productivity especially in arid and
semi-arid regions (Parvaiz and Satyawati, 2008). Salt stress causes hyperosmotic stress and ion disequilibrium,
thereby disabling the vital cellular functions of a plant. Reduced availability of water, increased respiration rate,
altered mineral distribution, membrane instability, failure in the maintenance of turgor pressure are some of the
events that prevails during this stress episode. Plants try to withstand these stresses either by tolerating it or by
adopting a dormant stage (Cuartero et al., 2006). Salt tolerance is a complex trait which involves numerous genes
and various physiological and biochemical mechanisms (Cuartero and Moreno, 2006). Proline content of
salt-stressed plants was previously reported in different species (Özcan et al., 2000; Turan et al., 2007). Lutts et al.,
(1999) suggested that proline accumulation in rice under salinity was most likely a symptom of injury rather than
an indicator of increased tolerance. However, Singh et al., (1996) emphasized the protective role of proline under
salinity. Mansour (1998) also suggested additive effects of proline upon salt tolerance via increased cell
membrane stability. Based on our results, we cannot distinguish between higher proline concentrations in leaf cells
being an indicator of injury or a protection mechanism. The decrease in K
+
/ Na
+
ratio and proline content in leaves
(indicated that the proline content of leaves may act as an indicator of Na
+
uptake and allow the identification of
tolerant varieties, which effectively exclude Na
+
from leaf tissue either by exclusion or compartmentalization in
root.
Phytohormones suggested playing important roles in stress responses and adaptation (Sharma et al., 2005; Hamdia
and Shaddad, 2013, 2014 & Hamdia, 2016). It is thought that the repressive effect of salinity on seed germination
