Abstract:
This study was carried out to evaluate the effects
of salinity stress (16 dS m
-1
) on proline
accumulation and expression pattern of three genes
involved in the proline synthesis
(P5CS, P5CR) and degradation (PDH) in the fourth an
d the flag leaves. The experimental
treatments consisted of two levels of salinity stre
ss including 1.6 (control) and 16 dS m
-1
and three wheat cultivars, namely, Hirmand and Cham
ran (as tolerant cultivars) and
Atrak (as sensitive). These were arranged as factor
ial based on a Completely Randomized
Design with three replications. There was an increa
se in Na
+
concentration and decrease
in K
+
concentration in salinity stress compared to the c
ontrol condition in the fourth and
the flag leaves of all cultivars. However, the tole
rant cultivars showed lower level of Na
+
concentration and higher level of K
+
concentration and K
+
/ Na
+
ratio. Seemingly, the
increase in proline accumulation was due to P5CS, P
5CR up-regulation and PDH down-
regulation.
On the other hand, the higher proline degradation i
n the fourth leaf of the
tolerant cultivars was probably due to the provisio
n of a source for energy or nitrogen,
which helped to enhance the yield of these cultivar
s under salinity stress.
Keywords
: Proline, Salinity, Wheat, P5CS, P5CR, PDH.
