STUDIES ON PHYSIOLOGICAL MARKERS OF SALT (NaCl) TOLERANCE IN SUNFLOWER (Helianthus annuus L.) GENOTYPES
KrishiKosh
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Title |
STUDIES ON PHYSIOLOGICAL MARKERS OF SALT (NaCl) TOLERANCE IN SUNFLOWER (Helianthus annuus L.) GENOTYPES
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Creator |
LAKSHMI, G
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Contributor |
MADHULETY, T Y
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Subject |
STUDIES, PHYSIOLOGICAL, MARKERS, SALT, TOLERANCE, SUNFLOWER, GENOTYPES
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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 |
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Date |
2016-08-20T12:04:30Z
2016-08-20T12:04:30Z 2003 |
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Type |
Thesis
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Identifier |
ACHARYA N.G. AGRICULTURAL UNIVERSITY RAJENDRA NAGAR, HYDERABAD - 500 03 0
http://krishikosh.egranth.ac.in/handle/1/73145 |
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Language |
en
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Format |
application/pdf
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