Abstract
Plant glutathione peroxidase (GPX) is an important antioxidant enzyme to maintain H2O2 homeostasis and regulate plant response to abiotic stress. In this paper, we present the first report of a genome-wide identification of GPX genes in watermelon. A total of six genes (ClGPX1–ClGPX6) were identified, which were unevenly located on four chromosomes of the watermelon genome. Based on phylogenetic analysis, the GPX genes of Arabidopsis, rice, cucumber, and sorghum were classified into four groups. Through analyzing the promoter regions of ClGPX genes, many development-, stress-, and hormone-responsive cis-acting regulatory elements were also identified. Expression pattern analysis by qRT-PCR indicated that all ClGPX genes were actively expressed in flowers and fruits, and exhibited relatively lower expression in other tissues, particularly roots and stems. In addition, the expression of ClGPX genes was significantly induced by salt, drought, and cold stresses, as well as abscisic acid (ABA) treatment at different time points, suggesting that they may be involved in response to abiotic stress and ABA. Taken together, our findings demonstrated that ClGPX genes might function in watermelon development, especially in flower and fruit tissue, as well as in response to abiotic stress and hormones.
Highlights
Plants are exposed to various abiotic stresses including drought, salt, and extreme temperature, which can induce the generation of reactive oxygen species (ROS) that seriously affect plant growth and development
To obtain a more comprehensive understanding of the glutathione peroxidase (GPX) gene family in watermelon, we identified six watermelon GPX genes in silico and analyzed their tissue-specific expression as well as their functions in response to various abiotic stresses including salt, drought, and cold stresses, as well as abscisic acid (ABA) treatment
Based on BLAST searches against the watermelon genome using sequences of Arabidopsis and rice GPX proteins as queries, a total of six putative GPX genes were identified, which were renamed as ClGPX1–ClGPX6 based on their order on the chromosomes (Table 1)
Summary
Plants are exposed to various abiotic stresses including drought, salt, and extreme temperature, which can induce the generation of reactive oxygen species (ROS) that seriously affect plant growth and development. To survive under these stresses, plants develop various enzymatic and non-enzymatic mechanisms to protect themselves from the adverse environmental effects caused by ROS [1,2]. For the Arabidopsis thaliana (L.) isoforms) is an efficient ROS scavenger that belongs to the non-haeme thiol peroxidase family and uses glutathione (GSH) and thioredoxin (Trx) as reducing substrates [3]. Compared with mammal GPXs, plant GPXs have a preference to Trx instead of GSH as the reducing substrate [4,5]. Eight GPX genes were identified in Arabidopsis, most of which were regulated to different degrees by salt and drought treatments in Arabidopsis wild-type (WT) plants and
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