title: Nitric oxide protects carbon assimilation process of watermelon from boron-induced oxidative injury.
abstract: Nitric oxide (NO) mediates plant response to a variety of abiotic stresses; however, limited information is available on its effect on boron (B)-stressed watermelon plants. The present study investigates the mechanism through which NO protects watermelon seedlings from B deficiency and toxicity stresses. Five days old watermelon seedlings were exposed to B (0, 0.5 and 10 mg L-1) alone or with 75 μmole of NO donor sodium nitroprusside (SNP) for 30 days. Both low and high B concentrations in the media altered nutrient accumulation and impaired various physiological processes of watermelon seedlings, leading to a significant reduction in biomass production. The plants exposed to B deficient or toxic concentrations had 66 and 69% lower shoot dry weight, respectively compared with optimum B levels. B toxicity-induced growth inhibition of watermelon seedlings was associated with high B translocation to shoot tissues, which caused lipid membrane peroxidation (12% increase) and chlorophyll destruction (25% reduction). In contrast, B deficiency accelerated generation of reactive oxygen species (ROS), specifically OH-1and induced cellular oxidative injury. Exogenously applied SNP promoted leaf chlorophyll, photosynthesis and consequently biomass production in B-stressed watermelon seedlings by reducing B accumulation, lipid membrane peroxidation and ROS generation. It also activated antioxidant enzymes such as SOD, POD and APX, and protected the seedlings from ROS-induced cellular burst.
authors.affiliation: Lab of Germplasm Improvement and Molecular Breeding, Agriculture and Biotechnology College, Zhejiang University, Hangzhou 310029, PR China; Horticulture Research Institute, 9 Gamaa Street, Giza 12619, Giza, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Farag
authors.affiliation: Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, NSW 2006, Australia. Electronic address: najeeb.ullah@sydney.edu.au.
authors.forename: Ullah
authors.initials: U
authors.lastname: Najeeb
authors.affiliation: Lab of Germplasm Improvement and Molecular Breeding, Agriculture and Biotechnology College, Zhejiang University, Hangzhou 310029, PR China.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Yang
authors.affiliation: Lab of Germplasm Improvement and Molecular Breeding, Agriculture and Biotechnology College, Zhejiang University, Hangzhou 310029, PR China.
authors.forename: Zhongyuan
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Lab of Germplasm Improvement and Molecular Breeding, Agriculture and Biotechnology College, Zhejiang University, Hangzhou 310029, PR China. Electronic address: mfzhang@zju.edu.cn.
authors.forename: Zhang Ming
authors.initials: ZM
authors.lastname: Fang
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D001895:Boron / Q000378:metabolism / Q000633:toxicity*; D002244:Carbon / Q000378:metabolism*; D002338:Carotenoids / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D029773:Citrullus / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D005453:Fluorescence; D005740:Gases / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D020011:Protective Agents / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000975:Antioxidants; D005740:Gases; D020011:Protective Agents; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D009599:Nitroprusside; D009569:Nitric Oxide; D002338:Carotenoids; D008315:Malondialdehyde; D002244:Carbon; D001895:Boron
keywords: Boron toxicity; Lipid peroxidation; Oxidative stress; Photosynthetic inhibition; Sodium nitroprusside