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Identification of physiological and molecular markers for salinity tolerance in wheat

KrishiKosh

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Title Identification of physiological and molecular markers for salinity tolerance in wheat
 
Creator ASHA
 
Contributor Dhingra, H.R.
 
Subject Salinity, Wheat, Membrane injury, Chlorophyll fluorescence reproductive parameters in vitro salinity tolerance, RGR
 
Description The present investigation was carried out on eight varieties of wheat viz. WH157, WH1021, RAJ3765, KRL19, WH711, PBW550, WH542 and PBW502, to screen them for salinity tolerance on the basis of sexual characters and yield, to find biochemical, physiological and molecular basis of salinity tolerance under in vitro and in vivo conditions and to select and evaluate salinity tolerant somaclones.
In the first experiment, all the eight varieties of wheat were subjected to a range of chloride dominated salinity viz. control 4, 8 and 12 dSm -1 to study its effect on physiological parameters like seedling emergence, chlorophyll fluorescence, membrane injury, photosynthetic rate, transpiration rate, water use efficiency, proline content and osmotic potential. In addition to these reproductive parameters like spike length, number of pollen/anther, pollen viability and in vitro pollen germination and yield and grain quality parameters like grain weight per spike, 100 grain weight, grain yield/plant, sedimentation value, hectoliter weight, starch and protein content of grain and mineral content (Na + , K + , Cl and SO 4 2-) were also recorded.
Salinity decreased and delayed seedling emergence in all varieties. It also exercised inhibitory effect on plant height particularly in PBW550, WH542 and WH711. Salinity increased electrolyte leakage of flag leaf,increase being maximum in variety WH711 followed by PBW550 while minimum in WH1021 followed by KRL19. Photosynthetic rate, stomatal conductance and transpiration rate decreased with increasing saline irrigation in all varieties, but PBW550, WH542 and PBW502 suffered most. Water use efficiency (WUE) remained nearly unchanged under saline conditions. Salinity induced accumulation of proline in flag leaf of all tested varieties;percent accumulation being highest in WH157 followed by KRL19 and least in PBW550 and WH711 at highest level of salinity. The Ψs of flag leaf became more negative with increasing level of salinity stress. Number of spikes/plant, spike length, number of florets/spikelet decreased with salinity. Pollen production, pollen viability (%), in vitro pollen germination and tube growth were also adversely affected with increasing salinity; the effect being most pronounced in varieties PBW550and WH711. The yield parameters like number of grains/spike, grain weight/plant, 100 grain weight decreased with increasing salinity, however varieties KRL19 and WH1021 were less affected than others. Grain quality parameters like sedimentation xvi value and hectoliter weight decreased at higher salinity levels. Reduction for sedimentation value was more in PBW550 over other varieties and least in WH1021. Biochemical studies also revealed a decline in protein and starch content of grain with increasingsalinity. Analysis of mineral composition of seed showed a decrease in K + /Na + ratio and an increase in chloride and sulphate content. Minimum reduction for K + /Na + ratio at 12 dSm -1 salinity was observed in KRL19 followed by WH157 and RAJ3765.
MS medium supplemented with 4 mg/l concentration of 2,4-D (MS1) was the best callusing and growth supporting medium for mature embryo. Culturing of actively growing callus on MS1 medium supplemented with a range of salinity (Control 4, 8 and 12 dSm -1 ) resulted in decline in RGR after 3 and 6 weeks of incubation. Varieties WH1021, WH157 and KRL19 possessed higher RGR than other varieties. Tissue culture studies adduced support to pot culture experiment for the parameters like osmotic potential, proline content, starch and protein content, K + /Na + ratio, Cl - and SO4 2- content at both stages of sampling i.e. after 3 and 6 weeks of incubation. Repeated sub-culturing of callus for 6 generations from sensitive varieties WH711 and PBW550 on MS1 medium with or without salinity, generated four different callus lines viz. control, salinity unadapted, salinity adapted and salinity adapted transferred to salinity free medium.
RGR, osmotic potential, starch and protein content, K + /Na + ratio decreased while proline, Cl and SO
4 2-content increased in all salinity exposed callus lines as compared to control. Salinityadapted callus lines performed better than salinity unadapted callus lines for all parameters. Adapted calli when transferred to salinity free medium showed improved performance in respect of different evaluation parameters.
Salinity induced synthesis of new polypeptide bands with M.W. 69.1, 36.3, 21.8, 17.3 and 15.1 kDa in salt tolerant WH1021 and in salt sensitive WH711,polypeptide bands with M.W. 79.4 & 75.8 kDa disappeared concomitant with synthesis of polypeptide bandswith M.W. 60.2, 36.3, 17.3 and 15.1 kDa.
 
Date 2016-08-08T11:13:53Z
2016-08-08T11:13:53Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/71440
 
Language en
 
Format application/pdf
 
Publisher CCSHAU