“DIFFERENTIAL GENE EXPRESSION OF AQUAPORIN FOR SALINITY STRESS IN GROUNDNUT”
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Date
2018-06
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JAU,JUNAGADH
Abstract
The present investigation was carried out at the Department of Biotechnology, Junagadh Agricultural University, Junagadh to study the differential gene expression of Aquaporin in salinity stress in groundnut (wild type – Arachis duranensis and GG 20 cultivated variety).
Peanut or groundnut (Arachis hypogaea L.) is a species in the legume or "bean" family and native to South America, Mexico and Central America. The groundnut is herbaceous, annual type of plant. Groundnut is an important food and cash crop for resource-poor farmers. It is primarily grown for edible oil (48–50%) as well as for direct consumption by people. Salinity affects at almost all the growth stage of groundnut, i.e. from emergence to maturity. So, salinity in soil during sensitive (critical) stages (flowering, pegging and pod formation) reduces final yield and oil content. The present investigation was carried out with an aim to study the candidate gene expression between control and salinity stressed tissues of wild type Arachis duranensis and GG 20 variety.
Variety GG 20 and Arachis duranensis were selected for this study. Arachis duranensis is a wild herb. Wild peanut are genetically diverse and were selected throughout evolution to a range of environments constituting therefore, it is an important source of allelic diversity for abiotic stress tolerance. GG 20 is cultivated in entire Gujarat except North Gujarat. It has high oil content and is high yielding variety. Salt stress was imposed by irrigating both the cultivars with sea water with ECe 4 dS m-1, ECe 6 dS m-1and ECe 8 dS m-1 after 19 days after treatment. Study was conducted with two main objectives. First was to study physio-biochemical changes in control and stressed condition. Second was to determine differential Aquaporin expression during salinity stress through real time PCR. The RNA concentration in the range of 24.9 – 63.0 µg/ml was selected for the study. cDNA synthesis was carried out for differential gene expression of Aquaporin genes.
Retrieving of sequences was carried out by searching conserved domain of Aquaporin membrane protein in the genome of Arachis duranensis and primers were designed using online tool batch primer-3 by selecting the generic option.
Real time assay was performed for 11 aquaporin genes at 8 ECe salinity level. 19 days salinity stress with constant volume of sea water (8 ECe) showed differential gene expression. In Arachis duranensis all genes were upregulated and in GG 20, 09 were up regulated, only two i.e. Aradu.0NC5M.1and Aradu.YIH2Y.1 were down regulated. Expression studies were conducted with Alcohol dehydrogenase as endogenous control. This information could be used to develop salinity tolerant groundnut.
Treatment wise decrease in relative water content was observed from T1 to T4 as the salinity level increased. Reduction of water content was found less in Arachis duranensis as compared to GG 20.
Electrolytic leakage (EL) was examined in response to salinity stress. EL was found more in GG 20 (36.45 to 92.04%) as compared to A. duranensis (29.82 to 80.29%) which proved tolerance of wild type against salinity.
The highest value (0.871mg.gm-1 fr.wt.) for total chlorophyll content was observed in control (T1) as compared to T4 (0.202 mg.gm-1 fr.wt.). Total chlorophyll content was found less in A. duranensis (0.783 to 0.167 mg.gm-1 fr.wt.) as compared to GG 20 (0.960 to 0.237 mg.gm-1 fr.wt.).
Increment in free amino acids was found more in A. duranensis (0.89 to 2.21 mg. g.-1) as compared to GG 20 (0.77 to 1.85 mg. g.-1). Total soluble sugars was found more in A. duranensis (0.41 to 0.90%) as compared to GG 20 (0.37 to 0.81%).
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BIOTECHNOLOGY