title: Hydrogen cyanamide breaks grapevine bud dormancy in the summer through transient activation of gene expression and accumulation of reactive oxygen and nitrogen species.
abstract: Hydrogen cyanamide (HC) and pruning (P) have frequently been used to break dormancy in grapevine floral buds. However, the exact underlying mechanism remains elusive. This study aimed to address the early mode of action of these treatments on accumulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and expression of related genes in the dormancy breaking buds of grapevine in the summer.
  
  
  
  The budbreak rates induced by pruning (P), hydrogen cyanamide (HC), pruning plus hydrogen cyanamide (PHC) and water (control) after 8 days were 33, 53, 95, and 0 %, respectively. Clearly, HC was more effective in stimulating grapevine budbreak and P further enhanced its potency. In situ staining of longitudinal bud sections after 12 h of treatments detected high levels of ROS and nitric oxide (NO) accumulated in the buds treated with PHC, compared with HC or P alone. The amounts of ROS and NO accumulated were highly correlated with the rates of budbreak among these treatments, highlighting the importance of a rapid, transient accumulation of sublethal levels of ROS and RNS in dormancy breaking. Microarray analysis revealed specific alterations in gene expression in dormancy breaking buds induced by P, HC and PHC after 24 h of treatment. Relative to control, PHC altered the expression of the largest number of genes, while P affected the expression of the least number of genes. PHC also exerted a greater intensity in transcriptional activation of these genes. Gene ontology (GO) analysis suggests that alteration in expression of ROS related genes is the major factor responsible for budbreak. qRT-PCR analysis revealed the transient expression dynamics of 12 specific genes related to ROS generation and scavenge during the 48 h treatment with PHC.
  
  
  
  Our results suggest that rapid accumulation of ROS and NO at early stage is important for dormancy release in grapevine in the summer, and the identification of the commonly expressed specific genes among the treatments allowed the construction of the signal transduction pathway related to ROS/RNS metabolism during dormancy release. The rapid accumulation of a sublethal level of ROS/RNS subsequently induces cell wall loosening and expansion for bud sprouting.
authors.affiliation: Ph.D. Program of Agricultural Science, National Chiayi University, Chiayi, 60004, Taiwan.
authors.forename: Boonyawat
authors.initials: B
authors.lastname: Sudawan
authors.affiliation: Department of Farmers' Services, Council of Agriculture, Taipei, 10014, Taiwan.
authors.forename: Chih-Sheng
authors.initials: CS
authors.lastname: Chang
authors.affiliation: Tainan District Agricultural Research and Extension Station, Tainan, 71246, Taiwan.
authors.forename: Hsiu-Fung
authors.initials: HF
authors.lastname: Chao
authors.affiliation: Department of Bioagricultural Sciences, National Chiayi University, Chiayi, 60004, Taiwan. mku@mail.ncyu.edu.tw.|School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA. mku@mail.ncyu.edu.tw.
authors.forename: Maurice S B
authors.initials: MS
authors.lastname: Ku
authors.affiliation: Department of Bioagricultural Sciences, National Chiayi University, Chiayi, 60004, Taiwan. yfyen@mail.ncyu.edu.tw.
authors.forename: Yung-Fu
authors.identifier: 0000-0002-8669-4693
authors.initials: YF
authors.lastname: Yen
mesh_terms: D035264:Flowers / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D006856:Hydrogen Cyanide / Q000494:pharmacology*; D057445:Plant Dormancy / Q000187:drug effects*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012621:Seasons; D027843:Vitis / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D006856:Hydrogen Cyanide
keywords: Dormancy breaking buds; Gene ontology; Grapevines; Hydrogen cyanamide; ROS