title: Cucumber (Cucumis sativusL.) Nitric Oxide Synthase Associated Gene1 (CsNOA1) Plays a Role in Chilling Stress.
abstract: Nitric oxide (NO) is a gaseous signaling molecule in plants, transducing information as a result of exposure to low temperatures. However, the underlying molecular mechanism linking NO with chilling stress is not well understood. Here, we functionally characterized the cucumber (Cucumis sativus L.) nitric oxide synthase-associated gene,NITRIC OXIDE ASSOCIATED 1(CsNOA1). Expression analysis ofCsNOA1, using quantitative real-time PCR,in situhybridization, and a promoter::β-glucuronidase (GUS) reporter assay, revealed that it is expressed mainly in the root and shoot apical meristem (SAM), and that expression is up-regulated by low temperatures. A CsNOA1-GFP fusion protein was found to be localized in the mitochondria, and ectopic expression ofCsNOA1in theA. thaliana noa1mutant partially rescued the normal phenotype. When overexpressingCsNOA1in theAtnoa1mutant under normal condition, no obvious phenotypic differences was observed between its wild type and transgenic plants. However, the leaves from mutant plant grown under chilling conditions showed hydrophanous spots and wilting. Physiology tolerance markers, chlorophyll fluorescence parameter (Fv/Fm), and electrolyte leakage, were observed to dramatically change, compared mutant to overexpressing lines. Transgenic cucumber plants revealed that the gene is required by seedlings to tolerate chilling stress: constitutive over-expression ofCsNOA1led to a greater accumulation of soluble sugars, starch, and an up-regulation of Cold-regulatory C-repeat binding factor3 (CBF3) expression as well as a lower chilling damage index (CI). Conversely, suppression ofCsNOA1expression resulted in the opposite phenotype and a reduced NO content compared to wild type plants. Those results suggest thatCsNOA1regulates cucumber seedlings chilling tolerance. Additionally, under normal condition, we took several classic inhibitors to perform, and detect endogenous NO levels in wild type cucumber seedling. The results suggest that generation of endogenous NO in cucumber leaves occurs largely independently in the (CsNOA1) and nitrate reductase (NR) pathway.
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Xingwang
authors.initials: X
authors.lastname: Liu
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Shudan
authors.initials: S
authors.lastname: Xue
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Yanlinq
authors.initials: Y
authors.lastname: Cai
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Wenzhu
authors.initials: W
authors.lastname: Qi
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Jian
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Xu
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.affiliation: College of Horticulture and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China; Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural UniversityBeijing, China.
authors.forename: Huazhong
authors.initials: H
authors.lastname: Ren
keywords: CsNOA1; chilling stress; cucumber; nitrate reductase; nitric oxide; transgenic plants