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Ahmad, Raza,Kim, Yun-Hee,Kim, Myoung-Duck,Kwon, Suk-Yoon,Cho, Kwangsoo,Lee, Haeng-Soon,Kwak, Sang-Soo Blackwell Publishing Ltd 2010 Physiologia plantarum Vol.138 No.4
<P>Plants synthesize compatible solutes such as glycinebetaine (GB) in response to abiotic stresses. To evaluate the synergistic and protective effect of GB, transgenic potato plants expressing superoxide dismutase (SOD) and ascorbate peroxidase (APX) targeting to chloroplasts (referred to as SSA plants) were retransformed with a bacterial choline oxidase (<I>codA</I>) gene to synthesize GB in chloroplast in naturally occurring non-accumulator potato plants (including SSA) under the control of the stress-inducible <I>SWPA2</I> promoter (referred to as SSAC plants). GB accumulation resulted in enhanced protection of these SSAC plants and lower levels of H<SUB>2</SUB>O<SUB>2</SUB> compared with SSA and non-transgenic (NT) plants after methyl viologen (MV)-mediated oxidative stress. Additionally, SSAC plants demonstrated synergistically enhanced tolerance to salt and drought stresses at the whole-plant level. GB accumulation in SSAC plants helped to maintain higher activities of SOD, APX and catalase following oxidative, salt and drought stress treatments than is observed in SSA and NT plants. Conclusively, GB accumulation in SSAC plants along with overexpression of antioxidant genes rendered the plants tolerant to multiple environmental stresses in a synergistic fashion.</P>
Raza, Ahmad,Kang, Byungchul,Lee, Junho,Ryu, Ho Jin,Hong, Soon Hyung Elsevier 2018 Materials & Design Vol.145 No.-
<P><B>Abstract</B></P> <P>A novel CrFeMoVMn<SUB>x</SUB> high entropy alloy (HEA) system was devised after screening done with thermodynamic constraints. The Mn content was varied (x=0, 0.5, 1 atomic ratio), with other elements kept in equiatomic ratios, to determine the effect of paired sigma-forming element (PSFE) content on microstructural and mechanical behavior. Alloys were successfully fabricated using a powder metallurgical method after mechanical alloying (MA) for an optimized minimum milling time. The milled powder was sintered using spark plasma sintering (SPS). The microstructural analysis indicated the appearance of a σ phase in the equiatomic quinary CrFeMoVMn<SUB>x</SUB> system, and the volume fraction of the σ phase varied directly by Mn content. The Mn0 system exhibited the formation of a single phase solid solution. The failure of thermodynamic prediction, the role of PSFE content and Md ¯ in σ phase appearance were investigated. The transition in mechanical behavior through a reduction in Mn content was also investigated and Mn1 exhibited the highest fracture strength, of 3183MPa, and hardness of 868 Hv, while Mn0 displayed the highest plasticity. This study demonstrates higher specific yield strength and hardness values compared to previously reported HEA systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The mechanical alloying optimization process have been illustrated schematically specifically for high-entropy alloys. </LI> <LI> The proposed alloy systems have challenged the thermodynamic predictions and formed sigma phase. </LI> <LI> The volume fraction of sigma phase is related with the concentration of paired sigma forming elements (PSFE) content. </LI> <LI> The alloys showed higher specific yield strength and hardness as compare to previously reported high-entropy alloy systems. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ahmad, Raza,Lim, Chan Ju,Kwon, Suk-Yoon 한국식물생명공학회 2013 Plant biotechnology reports Vol.7 No.1
Plants are frequently exposed to a plethora of environmental stresses. Being sessile creatures, they have to tolerate any stresses by altering their metabolism. To achieve tolerance, plants synthesize compatible compounds such as glycine betaine (GB). Continuous research over the years has increased our understanding about the mechanisms of stress protection by GB, which range from an osmolyte to a chaperone and from maintenance of reactive oxygen species to gene expression inducer. Various crop plants have also been transformed to synthesize GB along with model plants by introducing bacterial or plant genes. The GB-synthesizing crop plants exhibit enhanced tolerance to various abiotic stresses and out-yield wild-type plants in stressful conditions. GB has also been utilized to improve enhanced stress tolerance by utilizing it in gene stacking experiments due to its synergistic and stabilizing effects. It is reviewed here (along with comparative analysis of GB synthesis pathways and its mechanism to improve tolerance) showing that gene stacking by using GB as one component provides substantial protection. This synergistic role of GB leads us to hypothesize that it can be utilized in virtually any kind of gene stacking experiments to develop crop plants to be grown in arable and marginal lands for better tolerance to ever-changing environmental conditions and to ensure food security in underdeveloped regions of the world.
Raza Ahmad,Misbah Bilal,전재흥,김현순,Youn-Il Park,권석윤 한국식물생명공학회 2016 Plant biotechnology reports Vol.10 No.5
Transgenic potato (Solanum tuberosum L. cv. Desiree) plants expressing components of a novel cyanobacterial photorespiratory glycolate catabolism pathway were developed. Transgenic plant expressing glcD1 (glycolate dehydrogenase I) gene was referred to as synGDH and transgenic plants expressing gcl (glyoxylate carboligase) and tsr (tartronic semialdehyde reductase) genes simultaneously were designated as synGT. Both synGDH and synGT plants showed stable gene transformation, integration and expression. Enhanced glyoxylate contents in synGDH plants were detected as compared to synGT and non-transgenic (NT) plants. Phenotypic evaluation revealed that synGDH plants accumulated 11 % higher dry weight, while, tuber weight was 38 and 16 % higher than NT and synGT, respectively. Upon challenging the plants in high temperature and high light conditions synGDH plants maintained higher Fv/Fm and showed less bleaching of chlorophyll as compared to synGT and NT plants. These results indicate that genetic transformation of complete pathway in one plant holds promising outcomes in terms of biomass accumulation to meet future needs for food and energy.
Raza Ahmad,임찬주,권석윤 한국식물생명공학회 2013 Plant biotechnology reports Vol.7 No.1
Plants are frequently exposed to a plethora of environmental stresses. Being sessile creatures, they have to tolerate any stresses by altering their metabolism. To achieve tolerance, plants synthesize compatible compounds such as glycine betaine (GB). Continuous research over the years has increased our understanding about the mechanisms of stress protection by GB, which range from an osmolyte to a chaperone and from maintenance of reactive oxygen species to gene expression inducer. Various crop plants have also been transformed to synthesize GB along with model plants by introducing bacterial or plant genes. The GB-synthesizing crop plants exhibit enhanced tolerance to various abiotic stresses and out-yield wild-type plants in stressful conditions. GB has also been utilized to improve enhanced stress tolerance by utilizing it in gene stacking experiments due to its synergistic and stabilizing effects. It is reviewed here (along with comparative analysis of GB synthesis pathways and its mechanism to improve tolerance) showing that gene stacking by using GB as one component provides substantial protection. This synergistic role of GB leads us to hypothesize that it can be utilized in virtually any kind of gene stacking experiments to develop crop plants to be grown in arable and marginal lands for better tolerance to ever-changing environmental conditions and to ensure food security in underdeveloped regions of the world.
Kaleem Raza Kazmi,Faizan Ahmad Khan,Naeem Ahmad 대한수학회 2009 대한수학회지 Vol.46 No.6
In this paper, using proximal-point mappings technique of R-accretive mappings and the property of the fixed point set of set-valued contractive mappings, we study the behavior and sensitivity analysis of the solution set of the system of parametric generalized quasi-variational inclusions involving R-accretive mappings in real uniformly smooth Banach space. Further under suitable conditions, we discuss the Lipschitz continuity of the solution set with respect to parameters. The technique and results presented in this paper can be viewed as extension of the techniques and corresponding results given in [3, 23, 24, 32, 33, 34].