Isolation, purification and characterization of an ascorbate peroxidase from celery and overexpression of the AgAPX1 gene enhanced ascorbate content and drought tolerance in Arabidopsis

Abstract

BackgroundCelery is a widely cultivated vegetable abundant in ascorbate (AsA), a natural plant antioxidant capable of scavenging free radicals generated by abiotic stress in plants. Ascorbate peroxidase (APX) is a plant antioxidant enzyme that is important in the synthesis of AsA and scavenging of excess hydrogen peroxide. However, the characteristics and functions of APX in celery remain unclear to date.ResultsIn this study, a gene encoding APX was cloned from celery and named AgAPX1. The transcription level of the AgAPX1 gene was significantly upregulated under drought stress. AgAPX1 was expressed in Escherichia coli BL21 (DE3) and purified. The predicted molecular mass of rAgAPX1 was 33.16 kDa, which was verified by SDS-PAGE assay. The optimum pH and temperature for rAgAPX1 were 7.0 and 55 °C, respectively. Transgenic Arabidopsis hosting the AgAPX1 gene showed elevated AsA content, antioxidant capacity and drought resistance. Less decrease in net photosynthetic rate, chlorophyll content, and relative water content contributed to the high survival rate of transgenic Arabidopsis lines after drought.ConclusionsThe characteristics of APX in celery were different from that in other species. The enhanced drought resistance of overexpressing AgAPX1 in Arabidopsis may be achieved by increasing the accumulation of AsA, enhancing the activities of various antioxidant enzymes, and promoting stomatal closure. Our work provides new evidence to understand APX and its response mechanisms to drought stress in celery.

Recent Developments in Enzymatic Antioxidant Defence Mechanism in Plants with Special Reference to Abiotic Stress

“…Recently, genome-wide association studies (GWAS) have attracted the attention of scientist to understand the variation in traits with respect to single nucleotide polymorphisms (SNPs). Employing the GWAS approach, it was observed that Oryza sativa have eight SOD coding genes, while nine SOD coding genes were observed in Arabidopsis thaliana genome [ 42 , 43 ]. Furthermore, it was revealed that distribution of various isoforms of SODs are on five different chromosomes in O. sativa and on all five chromosomes in A. thaliana .…”

“…The expression of AgAPX1 gene was significantly increased under drought stress. The transformation with AgAPX1 gene conferred the drought resistance in the transgenic lines of Arabidopsis [ 43 ]. The APX gene from the Dioscorea alata cv.…”

Multi-omics Analysis Reveals Whether and how Naphthylacetic Acid Affects the Quality of Rehmannia Glutinosa

“…Products of 4CL are subsequently used by various oxygenases, reductases and transferases for biosynthesis of lignin, avonoids, anthocyanins, aurones, stilbenes, coumarins, suberin, cutin, sporopollenin, etc [38]. 4CL plays multiple important roles in plant growth and development by catalyzing the formation of CoA ester [50], regulates the biosynthesis of lignin, avonoids and and wall-bound phenolics [51,52] plays a compensatory role in normal development [35], mediates the rice blast resistance, oret development and lignin biosynthesis [53] and affects plant phenotype and resulted in dwarfed plants with a "bonsai treelike" appearance [54]; (3) For peroxidase, peroxidase possesses salt tolerance and antioxidant reaction [55], tolerance to chilling [56] and drought resistance [57], and promotes stomatal closure [42], and related to ROS and NO [58] and modulates ascorbic acid metabolism [59]; (4) For CCoAOMT, it is a key enzyme in the lignin biosynthesis pathway [60], and involved in lignin biosynthesis [61] and vanillin biosynthesis [62], and affects the accumulation of phenolic acids [14], and increases biomass production, Cd uptake and translocation [63]. In a word, these four genes were associated with phenylpropanoid biosynthesis, lignin biosynthesis, biomass, stress tolerance, growth, development and so on.…”

Antioxidants enzyme activity in Brassica oleracea var. acephala under cadmium stress

“…Ascorbate Peroxidase (APX) is a key enzyme responsible for the removal of excess hydrogen peroxide under both stress and normal conditions. [34]. It is responsible for reduction of hydrogen peroxide to water and monodehydroascorbate, using ascorbate as a substrate [35].…”