title: Abscisic Acid-Induced H2O2Accumulation Enhances Antioxidant Capacity in Pumpkin-Grafted Cucumber Leaves under Ca(NO3)2Stress.
abstract: With the aim to clarifying the role of the ABA/H2O2signaling cascade in the regulating the antioxidant capacity of grafted cucumber plants in response to Ca(NO3)2stress, we investigated the relationship between ABA-mediated H2O2production and the activities of antioxidant enzymes in the leaves of pumpkin-grafted cucumber seedlings. The results showed that both ABA and H2O2were detected in pumpkin-grafted cucumber seedlings in response to Ca(NO3)2treatment within 0.5 h in the leaves and peaked at 3 and 6 h after Ca(NO3)2treatment, respectively, compared to the levels under control conditions. The activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POD) in pumpkin-grafted cucumber leaves gradually increased over time and peaked at 12 h of Ca(NO3)2stress. Furthermore, in the leaves of pumpkin-grafted cucumber seedlings, the H2O2generation, the antioxidant enzyme activities and the expression ofSOD, PODandcAPXwere strongly blocked by an inhibitor of ABA under Ca(NO3)2stress, but this effect was eliminated by the addition of exogenous ABA. Moreover, the activities and gene expressions of these antioxidant enzymes in pumpkin-grafted leaves were almost inhibited under Ca(NO3)2stress by pretreatment with ROS scavengers. These results suggest that the pumpkin grafting-induced ABA accumulation mediated H2O2generation, resulting in the induction of antioxidant defense systems in leaves exposed to Ca(NO3)2stress in the ABA/H2O2signaling pathway.
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China; Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversityNanjing, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Shu
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University Nanjing, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Gao
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University Nanjing, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, College of Horticulture, Nanjing Agricultural University Nanjing, China.
authors.forename: Yinghui
authors.initials: Y
authors.lastname: Yuan
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China; Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversityNanjing, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.affiliation: Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, College of Horticulture, Nanjing Agricultural UniversityNanjing, China; Suqian Academy of Protected Horticulture, Nanjing Agricultural UniversityNanjing, China.
authors.forename: Shirong
authors.initials: S
authors.lastname: Guo
keywords: Ca(NO3)2 stress; abscisic acid; antioxidant enzymes; cucumber; grafting; hydrogen peroxide