ASSESSMENT OF BIOCHEMICAL AND MOLECULAR MARKERS IN DIFFERENTIATING SUGARCANE GENOTYPES FOR SALT TOLERANCE
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Date
2010
Authors
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Journal ISSN
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Publisher
MPKV,Rahuri
Abstract
Sugarcane (Saccharum officinarum L.) crop shows high sensitivity
to salinity at various growth stages. T.he present investigation entitled,
Assessment of biochemical and molecular markers in differentiating
sugarcane genotypes for salt tolerance" was undertaken with a view to
analyse the effect of salt stress on different sugarcane genotypes.
The sets of sugarcane were planted in normal soils. Then after one
!TIOnth, the seedlings were transplanted to bigger earthen pots in normal,
aline and sadie soils. The leaves from 75 days old plants were excised
or the estimation of various biochemical parameters viz., proline, glycine
etaine,soluble proteins, in vivo NR activity and the activity of PSCS.
f urther,the leaf soluble proteins were extracted from sugarcane leaves
grown on normal, saline and sadie soils and resolved on SDS-PAGE. The
ifferences in isozyme forms of peroxidase and esterase were also
bserved. The genomic DNA' isolated and purified from the sugarcane
enotypes was amplified using different random primers.The leaf free proline content of all the sugarcane varieties
increased_, the mean proline accumulation fFom 99.97 to 114.43 J..1 mole
g-1 fr.wt. in saline soil and from 99.97 to 122.76 J..1 mole g-1 fr.wt. m sorlic
soil. Comparison of the leaf prelme €ontents wblen gFOwn on normal,
saline and sodic soils revealerl ~ferenees m feld increase in proline.
Sugarcane genotypes CoM-0265,Co:-740 and Co-62175 showed an
increase in proline content of 1.26, 1.25 and 1.22 .. £old in sa1ine soil and
1.34, 1.49and 1.28 -fold in sodic S0ilS, respectively. Amongst the
promising clones, CoM -08011 appeared to 1De sa1t tolera.I'lt showing an
increase in leaf proline content of 1.1 ~and 1.25 fold under salline and
sodic conditions. It thus appears that fold increase in pF®line level is a
sensitive parameter while evaluating salt toleFance and pFoline
accumulatoin is an adaptive parameter unde:r stress c0naition. The early
maturing and high sugar genetypes viz., CoC-671 and Co-940 12
appeared to be salt susceptible. ·A significant increase in mean g~cine
,betaine content was recorded with 4.34-fold increase in saline soils and
16.63 fold in sodic soils. A maximum fold iiacrease in glyci~e betaine
content of 10.44 and 51.06 fold was reco~ded in CoM-0265, followed by
Co-7 40 with a fold increase of 8.19 and 27.28 in saline and sodic soils~
respectively . The early maturing aE.d nigfu suga:r centaining sugarcane
genotypes,.,CoC-671 and Co-94012 showed the minimum fold increase of
2.45 and 1.68, respectively when grown on saline soils and 7.42 and
6.77 when grown on sodic soils.The soluble protein content also
increased under stress aE.dWlehighest fold increase ef 2.52 and 4.18 was
observed in CoM-0265 in saline and sodic soils,respeetively. 1'he increase
in free proline content is not due te proteolysis but rather due to
increased de-novo synthesis.
The in vivo leaf nitrate reductase activity was drastically
reduced when grown on saline and sodie soils. A :m.inimum reduction in
the in vivo NR activity from 0.62 in normal soH to 0.54 J..1 mole N02~
fromed g-1 fr.wt.hr-1 in saline soil was recorded in CoM-0265, followed
by a reduction of 14.46 % in Co-740. It is interesting to note that early
aturing and high sugar genotypes, CoC-671 and Co-94012 showed
igher in vivo NR activity of 1.63 and 1.61 j..1 mole N02- formed g -~
r.wt.hr-1 , respectively when grown on normal soils. However , the
eduction in the in vivo NR activity was significant to the extent of 32.90
Yo in CoC-671 and 43.52% in Co-94012 in saline soils and 62.64% and
4.66% in sodic soils.