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The stability of enzymes with no reduction in their catalytic activity still remains a critical issue in industrial applications. Naturally occurring osmolytes are commonly used as protein stabilizer. Apart from increasing the stability and catalytic activity, these osmolytes do not change the structure of enzyme. There are a few general schemes about the stabilization mechanism of these osmolytes but the details of their mechanism have not been found so far. In this study, we investigated the simultaneous effects of sorbitol and trehalose on the activity and structural stability of Pseudomonas cepacia lipase (PCL) using UV–visible, fluorescence and circular dichroism (CD) spectroscopy. In order to trace the refractive index and dielectric constant alterations upon the addition of osmolytes, microenvironment of the enzyme (PCL) was studied by means of SPR technique.The results revealed that osmolytes increased catalytic activity and intrinsic fluorescence intensity of PCL. In the presence of both osmolytes the activity of enzyme is greater than when each of the osmolytes is used individally. Far-UV CD spectra indicated that the secondary structural content of protein has been some what increased upon interacting with these osmolytes.The results of SPR technique indicated none of the above osmolytes could change the dielectric constant of medium considerably. This study revealed the synergy of two osmolytes toward increasing the activity and stability of enzyme.

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Seed priming can restore age-induced loss of seed viability or longevity; however, these invigoration responses may vary with priming agents and seed aging duration. The present study investigated the effect of two potassium salts (K-salts) individually and in combination (1:1) on different lots of muskmelon genotype, MS-1 seeds stored for four consecutive years, from 2013 to 2016 under ambient conditions. The combination of K-salts significantly enhanced the percent germination of seeds stored for two years (from 2015 to 2016). Further, it also improved root morpho-traits of 10-day-old seedlings. The storage duration had significant effect on the seed surface bacterial and fungal populations. A significantly higher cfu mL^-1 microbial counts were recorded for 2013 harvested seeds on three different agar-based media compared to 2014 to 2016 stored seeds. Further, the Scanning EM and FT-IR study revealed the surface microbiological status and functional groups variations, respectively. Thus, aging-related seed coat microflora is responsible for deterioration of the seed coat. Osmo-conditioning cannot restore viability of seeds stored under ambient conditions for more than two years.
 

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Drought is a major abiotic stress in arid and semi-arid areas. This study examines how drought stress and different rootstocks affect aerial part physiology and macronutrient uptake in two seedlings of pear cultivars, 'Dargazi' and 'Louise Bonne,' grafted onto 'Dargazi' and 'Pyrodwarf' rootstocks. Treatments were well-watered as control (100% Field Capacity, FC), moderate (60% FC), and severe drought (30% FC). Drought stress decreased the Root-to-Shoot weight ratio (R/SH), Leaf Relative Water Content (LRWC), Soluble Protein (SP), Photosynthetic Nitrogen Use Efficiency (PNUE), leaf osmotic potential (Ψs), Leaf potassium (LK⁺), Root Calcium (RCa²⁺), Root Nitrogen (RN), Stomatal aperture (SA), net photosynthetic rate (An), transpiration rate (E), stomatal conductance (gs), and instantaneous carboxylation Efficiency of Rubisco (EiC) in all scion-rootstock combinations. Under drought stress, levels of proline (Prol), Glycine Betaine (GB), Total Soluble Carbohydrate (TSC), root potassium (RK⁺), leaf calcium (LCa²⁺), leaf nitrogen (LN), leaf and root phosphorus (P) increased. 'Dargazi' as the cultivar or rootstock showed better instantaneous Water Use Efficiency (WUEi), Nitrogen Utilization Efficiency (NUtE), and Nitrogen Uptake Efficiency (NUpE), with higher LN, LNO³⁻, LNH⁴⁺, Prol, and Ψs under severe stress. 'Louise Bonne' had higher amounts of R/SH weight ratio, Total Nitrogen Accumulation (TNA), leaf and root nitrate reductase activity (NRA),  An, intracellular carbon dioxide concentration (Ci), E, and root nitrate (RNO³⁻) under moderate stress. 'Pyrodwarf' rootstock demonstrated the highest TNA and RCa²⁺ under moderate stress conditions. These results indicated that 'Dargazi' demonstrated better tolerance under severe stress, while 'Pyrodwarf' and 'Louise Bonne' were more effective under moderate stress conditions.