Water limitation is a well-known problem for wheat plants. Lack of water affects their biomass and yield.
This is the most conspicuous in case of crops causing severe uncertainty of agricultural productivity. Progress in
breeding to improve drought tolerance has been limited by its high sensitivity to environmental factors, low heritability,
and the complexity and size of wheat genome. In this study eight genotypes of bread wheat were used for screening
them under three water regimes; control 100% Field Capacity (FC), 75% FC and 50% FC. Five drought resistance
indices including Mean Productivity (MP), Tolerance Index (TOL), Drought Susceptibility index (DSI), Geometric
Mean Productivity (MP) and Yield Stability Index (YSI) were calculated for each genotype based on grain yield under
stress (50% FC) and normal (100% FC) conditions. Physiological parameters, chlorophyll content (SPAD values),
proline accumulation and expression levels of drought related genes were analyzed in wheat plants at heading stage,
comparing eight genotypes with different drought tolerance capacity. The imposed drought stress induced a decreasing
of plant growth and chlorophyll content, a strong increase in proline and expression of drought related genes. The
correlation coefficients showed that YSI, MP, DSI and GMP had the most desirable selection criteria for high yielding
and drought tolerant genotypes. The development of molecular markers for physiological traits has made significant
headway in recent years with the advancement of new technologies. Consequently, in our study the use of molecular
markers; RAPD technique with 9 primers was detected 91 polymorphism alleles for the genotypes with 79.12%
polymorphism. The most Polymorphic Information Content (PIC) value and polymorphism percentage was detected by
OPA-07primer that showed the high score from bands 13 with polymorphism 69.23%. While, OPO-19 revealed low
level from bands was 6 with percentage 83.33%. Also, OPA-02, OPA-04 and OPO-13 revealed 9 fragments with
77.78% polymorphism. While, primers OPB-07, OPB-10 and OPO-14 showed 11 bands with 81.82% polymorphism.
The last primer revealed 12 bands with 75% polymorphism. Therefore, these recently developed techniques could be
enable faster identification and characterization of drought-related gene(s).