Assessment Of Heat Shock Proteins, Biochemical Constituents And Molecular Characterization In Sorghum In Relation To Heat Shock Response
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Date
2011
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MPKV, UNIVERSITY LIBRARY RAHURI
Abstract
The present investigation was undertaken to study heat shock
response in sorghum at biochemical and molecular level. The objectives of
this investigation was to study heat shock proteins profile in relation to heat
shock response in sorghum, to estimate the biochemical constituents
associated with heat shock response and to analyse the germplasm in relation
to heat shock response by molecular markers.
Nineteen genotypes of Sorghum bicolor (L.) Moench.,
consisted of six drought tolerant, six drought susceptible and seven wild
genotypes have been used to study the effect of heat stress in their seedling
stage. Heat shock protein profile, chlorophyll content, chlorophyll stability
index, proline, pyrroline-5-carboxylate synthetase, antioxidant enzymes viz.,
superoxide dismutase, peroxidase, and catalase were used as key parameters
to assess heat shock response.
In the present study, novel heat shock proteins are synthesized in
drought tolerant, drought susceptible and wild genotypes of sorghum under heat
stress condition. It was revealed that ~77.56 and ~70.80 kDa Hsps were observed in
M-35-1, ~73.25 kDa Hsp in IS 18855, a wild genotype under heat stress condition.
However, ~76.50 kDa and ~76.78 kDa were observed in SPV-1349 and SPV1502
respectively the drought susceptible genotypes under heat stress
condition.
The result indicated that Chlorophyll ‘a’, chlorophyll ‘b’ and total
chlorophyll content decreased in stressed condition. In an average among
nineteen sorghum genotypes IS 18872 showed higher chl ‘a’, chl ‘b’ and total
chlorophyll content. Chlorophyll stability index also showed same trend like
total chlorophyll content, it get decreased in heat stress treatment.
It was found that proline content in the leaves of stressed
seedlings of all the nineteen sorghum genotypes increased over the control
one. Among the nineteen sorghum genotypes absolute amount of proline
content and magnitude of increase in proline was highest in M-35-1. The
activity of bifunctional enzyme, pyrroline-5-carboxylate synthetase increased
in the leaves of all the nineteen sorghum genotypes. The activity was more
pronounced in drought tolerant genotypes; however highest fold increase in
P5CS content in a drought tolerant genotype SPV-1546 (41 fold) was
observed among all genotypes.
The activity of antioxidant enzymes viz., superoxide dismutase, peroxidase
and catalase activity increased during in response to imposed heat stress in
nineteen sorghum genotypes. Higher activity of superoxide dismutase and
peroxidase was noticed in a drought tolerant genotype, M-35-1 amongst all
other sorghum genotypes. Highest fold increase of catalase enzyme activity
was observed in RSV-458.
In RAPD analyses, Out of the 15 primers, 09 primers amplified
and showed the polymorphism in nineteen sorghum genotypes. A total of 76
loci were generated by amplification with 09 primers out of which, 70 loci
were polymorphic with 92.85 % polymorphism. Each primer thus produced
on an average 7.77 loci in the size ranging from 0.24 to 2.94 kb in the 19
sorghum genotypes.
The PIC values of primers ranged from 0.034-0.31.
Maximum, 0.31 PIC value was observed in OPM 18 primer. The highest Rp
value was observed in 1.51 in OPL 08 (1.51) and in OPL 18 (1.24).
A total 12 SSR primers used and 08 primers were amplified the
genomic DNAs of sorghum. Out of total 52 alleles, produced by these
primers, 31 were polymorphic loci with 100 % polymorphism. The PIC
values of primers ranged from 0.30-0.85 in SSR primers. Xtxp92 showed
maximum PIC value (0.85). Resolving power (Rp) values of the primers
ranged from 0.15 (Xtxp92) to 0.40 (Xtxp93).
The Dice similarity coefficient values based on RAPD markers
data ranged from 0.34 to 0.91 whereas SSR marker showed 0.12 to 0.57
range. Minimum similarity coefficient of 0.34 was observed between
Drought tolerant genotype SPV 1546 and wild genotype IS 18833 by RAPD
data whereas SSR data showed minimum similarity coefficient 0.12 between
drought tolerant genotype RSLG-262 and drought susceptible genotype
SPV-1502.
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