title: Growth medium alterations improve in vitro cold storage of pear germplasm.
abstract: BACKGROUND
  Development of new fruit cultivars is dependent on genetic resource collections such as those at the Pomological Garden of the Institute of Horticulture and Viticulture near Almaty, Kazakhstan. The pear germplasm collection of the Pomological Garden contains 615 cultivars and three species. In vitro cold storage of the collection would provide additional security to the field collection.
  
  
  OBJECTIVE
  This study was designed to improve medium-term in vitro storage of pear germplasm.
  
  
  METHODS
  Shoots of seven pear cultivars (Pyrus communis L.) were stored in plastic five-section bags at 4 degree C and a 10-h photoperiod (7 μmol/m2/s). Treatments included medium with four carbohydrate sources (3% sucrose, 2% or 3% mannitol, or 2% sucrose + 2% mannitol) with 0.5 mg/l BAP and 0.1 mg/l IBA or without plant growth regulators (PGRs) and at three Murashige and Skoog (MS) nitrogen concentrations (100%, 50% or 25%).
  
  
  RESULTS
  Pear shoots remained viable for 9 to 15 months without repropagation on the control MS medium with 3% sucrose without PGRs. There were significant impacts of cultivar and treatment on the duration of cold storage. Shoots of 'Mramornaya' remained viable (rating of ≥ 2) for 27 months with PGRs and 2% sucrose + 2% mannitol compared to 12 months for the PGR + 3% sucrose treatment. Talgarskaya Krasaviza stored for 18 months on 2% sucrose + 2% mannitol while all other treatments lasted only 6 to 9 months. Treatments with 0.5 or 1 mg/l abscisic acid (ABA) with 3% sucrose increased storage duration as did reducing the concentration of nitrogen in the medium to 25% without PGRs and with 3% sucrose.
authors.affiliation: Institute of Plant Biology and Biotechnology at National Center of Biotechnology, Almaty, Republic of Kazakhstan. kovalchuk_i_u@mail.ru.
authors.forename: I
authors.initials: I
authors.lastname: Kovalchuk
authors.affiliation: Institute of Plant Biology and Biotechnology at National Center of Biotechnology, Almaty, Republic of Kazakhstan.
authors.forename: Z
authors.initials: Z
authors.lastname: Zhumagulova
authors.affiliation: Institute of Plant Biology and Biotechnology at National Center of Biotechnology, Almaty, Republic of Kazakhstan.
authors.forename: T
authors.initials: T
authors.lastname: Turdiev
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository, Corvallis, OR, USA. Barbara.Reed@ars.usda.gov.
authors.forename: B M
authors.initials: BM
authors.lastname: Reed
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D050260:Carbohydrate Metabolism; D003080:Cold Temperature; D003470:Culture Media / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018520:Plant Shoots / Q000502:physiology*; D031989:Pyrus / Q000502:physiology*; D012034:Refrigeration
chemical_list: D003470:Culture Media; D010937:Plant Growth Regulators; D000040:Abscisic Acid; D009584:Nitrogen