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STUDIES ON PHYSIOLOGICAL MARKERS OF SALT (NaCl) TOLERANCE IN SUNFLOWER (Helianthus annuus L.) GENOTYPES

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Title STUDIES ON PHYSIOLOGICAL MARKERS OF SALT (NaCl) TOLERANCE IN SUNFLOWER (Helianthus annuus L.) GENOTYPES
 
Creator LAKSHMI, G
 
Contributor MADHULETY, T Y
 
Subject STUDIES, PHYSIOLOGICAL, MARKERS, SALT, TOLERANCE, SUNFLOWER, GENOTYPES
 
Description In the present study, sunflower genotypes PAC-36, APSH-11,
KBSH-1 and Morden were tested both under pot culture and in vitro
conditions with an objective of identifying the most tolerant genotype for salt
(NaCl) stress and to ascertain the physiological markers of salt tolerance.
Biometric data viz., germination, seedling growth, critical age of
seedlings and in vitro observations on callus growth were recorded. Among
the genotypes, PAC-36 was found significantly superior over all other
genotypes in respect of seed germination. It germinated even upto E.C level 8
dSm-1 while all others could germinate only upto 6 dSm-1. In general, increase
in salinity significantly reduced the seedling length and fresh weight.
Increased salinity levels enhanced proline and glycinebetaine accumulation in
21-day old seedlings more in PAC-36 followed by KBSH-1 while they were
the least with Morden and APSH-11.
Hypocotyl, cotyledon and root explants of all the genotypes were
challenged by 80 mM, 160 mM, 240 mM and 320 mM salt (NaCl)
concentrations and with varied hormonal combinations. Maximum callusing
was recorded by cotyledon, hypocotyl and root segments in MS-media
fortified with 1.5 mg/l NAA + 0.5 mg/l BA, while embryo could do better
callusing when a hormonal combination was changed as 1 mg/l 2,4-D + 0.5
mg/l kinetin. In general, increased salinity stress delayed callus induction and
decreased the fresh weight of callus. Cotyledon and hypocotyl tissues of
PAC-36 produced callus even at 320 mM (inhibitory to other genotypes) salt concentration. Highest mean callus fresh weight was recorded by KBSH-1
(cotyledon) followed by PAC-36 (hypocotyl) while Morden had the least. The
root explants of PAC-36 and APSH-11 totally failed to induce callus whereas
KBSH-1 and Morden could callus upto 240 mM and 160 mM salt (NaCl)
concentrations respectively.
The superior growth performance of PAC-36 over other genotypes
both under ex vitro and in vitro conditions prompted to study salt stressed
calli derived from PAC-36 to study and identify the basis for salt tolerance.
Hence, by knowing the isozymic pattern of Betaine aldehyde dehydrogenase
(BADH), Trehalase, superoxide dismutase (SOD), Peroxidase (POX)
enzymes and profiles of total protein, different pathways for salt tolerance can
be identified, established and exploited. SDS-PAGE analysis of total protein
in PAC-36 derived calli showed new bands (profiles) in highest salt (320
mM) stressed calli which were absent in control. A single isomorph of BADH
enzyme was observed in leaf tissues of 7-day old seedling of sunflower (cv.
PAC-36) stressed at E.C 8 dSm-1. Trehalase activity was also seen to increase
with increasing salt concentration in PAC-36 derived calli while it was totally
absent in control. The enzymes of anti-oxidative scavenging system (AOSS)
viz., superoxide dismutase (SOD) and peroxidase (POX) showed variation in
their zymogramic pattern with increasing salinity stress. Although
over-expression of these enzymes was not predominantly seen but showed
expression of variant isomorph at highest salt (320 mM) concentrations,
unlike in control (non-salt stress).
Since each genetically determined isoenzyme subunit type is the result
of a different gene and hence isoenzyme subunit is a marker for its own gene.
Therefore, the present investigation shows possibilities of induction of genes
for salt which are not found in native plants. Secondly, our results encourages
the mechanisms of putative gene synthesis by simulating abiotic stresses in
vitro or ex vitro conditions. The present work also demonstrates the
importance of totipotency of the explant carrying the gene of interest to
facilitate tissue culture multiplication of explant carrying the gene of interest.
Hence, present study paves the way for biotechnological exploitation to isolate the gene of interest and add to existing limited gene pool
 
Date 2016-08-20T12:04:30Z
2016-08-20T12:04:30Z
2003
 
Type Thesis
 
Identifier ACHARYA N.G. AGRICULTURAL UNIVERSITY RAJENDRA NAGAR, HYDERABAD - 500 03 0
http://krishikosh.egranth.ac.in/handle/1/73145
 
Language en
 
Format application/pdf