GENETICAL AND BIOTECHNOLOGICAL STUDIES ON SALINITY
TOLERANCE IN RICE
Ebrahim Abd El-Salam Mohammed Ramadan
ABSTRACT
Salinity is one of the major environmental stresses that limit
productivity of rice and other crops worldwide. Four Egyptian rice
varieties i.e. Giza177, Sakha101 (salt susceptible varieties), Sakha104
(moderately salt tolerance variety) and Giza159 (tolerant variety) were
crossed and one hundred doubled haploid lines (DHLs) were developed
using F1-anther culture technique. The DHLs, the four parents and two
salinity check varieties (TCCP 266-2-49-B-B-3 as a salinity tolerant
check variety and IR 29 as a sensitive check variety) were evaluated
under normal conditions and Lysimiter conditions (tap water, 4000 ppm
and 6000 ppm). Genetic variability, phenotypic correlation coefficients
and path co-efficient analysis were estimated under normal and Lysimiter
conditions. For molecular evaluation, twenty two genotypes were selected
and studied by using total soluble proteins (TSP), simple sequence
repeats (SSR) and intron-exon splice junctions (ISJ) techniques. The
results indicated that, the all studied characters for all genotypes exhibited
decreased estimations under salinity treatments (4000 ppm and 6000
ppm) compared with the control treatment (tab water) except for days to
heading. For genetic parameters, the phenotypic and genotypic variation
increased for most traits compared with respective tap water treatment .
The high estimates of Genetic coefficient of variation (G.C.V.),
Heritability (h2%) and Genetic advance percentage (G.A. %) were
observed for flag leaf area, pollen fertility, sterility percentage, grain
yield plant-1 and straw weight plant-1 suggesting that these traits could be
improved by direct selection under saline soil conditions. For phenotypic
correlation coefficient, under all treatments, significant and high
significant positive correlations were observed between grain yield plant -1
and each of flag leaf area, plant height, straw weight plant-1, panicle
length, panicle weight and harvest index. For path co-efficient analysis,
the traits straw weight plant-1, one thousand grain weight and pollen
fertility had positive direct effects on grain yield under all treatments. For
SSR markers, five SSR markers were used i.e. RM208, RM223, RM224,
RM276 and RM315, all of them generated polymorphic bands among the
genotypes except RM315. A total of eleven alleles were detected among
the twenty two genotypes. The number of alleles per locus ranged from
one to three, with an average of 2.2 alleles per locus. Three ISJ Primers
i.e. ISJ-5, ISJ-7 and ISJ-9 were used. The number of generated DNA
fragments was ranged between six for ISJ-7 and seventeen fragments for
ISJ-5 producing polymorphic ratio of 82.05% in average.