Triticeae Genomics and Genetics 2016, Vol.7, No.02, 1
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the stress. (Gilbert et al., 1998) added other possible
roles played by amino acids such as serving as readily
available energy source or as nitrogen source during
limited growth and photosynthesis, detoxification of
excess ammonia under periods of stress and
stabilization of enzymes and /or membranes might be
achieved.
In cv. Sakha 94 proline content dropped quickly and
surprisingly in roots at all salinization levels,
increases in highly significant in stems and spikes and
remained unchanged in leaves up to 150 mMNaCl.
Also, the growth and the crop yield in this genotype
were estimated greatly under salinity condition. In cv.
Gimiza 11 three faces occurred on the effect on the
accumulation of proline in roots according to salinity
level: a- It reduced markedly up to 150 mM NaCl. a-
Accumulated highly and quickly at 300 mM NaCl. In
leaves of cv. Gimiza 11 proline content remained
unchanged up to 150 mM afterthat, it accumulated at
300 mM NaCl and reduced in stems. While in spikes,
proline accumulated greatly in the all salinity levels.
Also, the dry matter accumulation in this cultivar
remained more or less unchanged whatever the
salinity level used.
It is worthy to mention that proline content in cv.
Gimiza 10 reduced sharply in roots, stems, leaves and
spikes which were interestingly and surprisingly
accompanied with the excessive reduction in dry
matter yield in the four plant organs especially at
higher salinity stress levels. Thus in this cultivar, the
two processes (the accumulation of dry matter and
proline) seemed to be revealed parallel to each other.
In the most sensitive cultivar Giza 168 proline content
seemly to be in the most cases remained more or
less unchanged in four plant organs at most
salinization level. Interestingly it was found to be
accompanied with a great reduction in the dry matter
yield in four plant organs and consequently in crop
yield production. Accordingly the correlation between
proline content and dry matter yield in the four
cultivars revealed 3 scenarios. The two processes went
to opposite to each other in the most cases in cv.
Sakha 94 and to some extent in cv. Gimiza 11, (i.e. the
great reduction in proline accompanied with a great
stimulation in dry matter yield).Proline content
remained more or less unchanged in Giza 168
accompanied with a great reduction in dry matter yield,
they also went opposite to each other.
Interestingly and surprisingly the two processes
revealed parallel to each other only in wheat cultivar
Gimiza 10, where the great reduction in proline
content accompanied with a great reduction in dry
matter yield in the four plant organs. All the three
scenarios and interpretations indicated the complexity
and diversity in the correlation between criteria of
proline and the differences in the salt tolerance among
the four studied cultivars and their organs which
weakness the physiological significance of proline
even to what can proline is a sign for salt tolerance or
saline injury should be taken with care.
The problematical behavior of proline could
accompany with the criteria in the synthesis and
proline degradation during stress condition. The
accumulation or reduction of proline could
accompanied with the activity of the enzymes
responsible for the synthesis or the degradation of
proline (proline turn over).The biosynthesis and
degradation of proline did not equilibrated. (I.e.
troubling in the
de novo
synthesis).Some researchers
have suggested that proline accumulation may be
related to the degree of salt tolerance and/ or osmotic
tolerance (Ashraf and Iram, 2005; Hassineet al.,
Ghanem, 2008; Rajaravindran; Natarajan, 2012).
While, in contrast, others have suggested that it is a
symptom of salt-stress injury rather than an indicator
for resistance (Lutts
et al
., 1996 a, b; Ashraf and Harris,
2004; Mansour
et al
., 2005).
The response of crops to salinity is a complex
phenomenon and involves changes in plant morphology
and physiology. Such modifications in plant
physiology may lead to the accumulation or depletion
of certain metabolites, alteration in the behavior of
many enzymes and synthesis of new sets of proteins
referred as salt-tolerant proteins (Ben-Hayyim
et al
.,
1989).
3 Materials and Methods
Vegetative growth stage and crop yield stage (long
duration experiment): A pot experiment was carried
out in open air at the garden of the Faculty of
Science-Minia University during winter season (from
the beginning of November to the middle of March).
Wheat seeds cultivars (Sakha94, Gimiza11, Gimiza10,
and Giza168) which brought from three different
