Temperature-dependent Flower Malformation in Carnations (<i>Dianthus caryophyllus</i> L.)

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Abstract

<p>Temperature regimes that cause malformed flowers were examined and histological observation was carried out at the developmental stage of flowers by using mutants of the potted carnation (<i>Dianthus caryophyllus</i> L.) 'Cherie' producing malformed flowers according to cultivation season. Plants of normal (WT) and malformed (<i>mlf</i>) lines were grown under several temperature regimes. All WT plants produced normal flowers, whereas <i>mlf</i> lines showed a variety of malformed floral phenotypes, including phyllody-like proliferated sepaloids, proliferated petaloids, proliferated pistillodes with or without petals, secondary flower formation, and a flattened receptacle. In Experiment 1, <i>mlf</i> plants produced no malformed flowers when grown under constant 26°C, whereas 34.2% of <i>mlf</i> plants produced malformed flowers at 14–16/12°C (day/night, natural light). Malformation frequency was slightly lower at a night temperature of 5°C compared with 14–16/12°C. When malformed <i>mlf</i> plants were transferred from 17/5°C to 23/18°C, flower malformation was alleviated. Conversely, when <i>mlf</i> plants grown under constant 26°C with a normal phenotype were transferred to 17/12°C, flower malformation was induced. Thus, flower malformation was reversible depending on the temperature regime. In Experiment 2, 92.2% of <i>mlf</i> plants produced malformed flowers under constant 15°C, whereas 3.1% and 1.3% showed flower malformation when grown under constant 20°C and 25/20°C, respectively. These findings suggested that the threshold for flower malformation is between 15°C and 20°C. Observation of shoot apices by optical microscopy and scanning electron microscopy revealed morphological differences between WT and <i>mlf</i> after sepal formation. Petal primordia were not visible in <i>mlf</i> plants at 15°C, although petal primordia were initiated in WT. After this stage, flower malformations observed in <i>mlf</i> included undeveloped petals, undeveloped or irregularly developed stamens, secondary flower primordia formation, and completely irregular arrangement of undeveloped flower organs. No phytoplasma was detected by PCR, indicating that it could not be the causal agent of the abnormal phenotypes. This is the first report of mutant flower phenotypes dependent on temperature and induced by only a 5°C difference within optimal growing-temperature regimes in carnations.</p>

Journal

  • The Horticulture Journal

    The Horticulture Journal 87(3), 406-412, 2018

    The Japanese Society for Horticultural Science

Codes

  • NII Article ID (NAID)
    130007420621
  • NII NACSIS-CAT ID (NCID)
    AA12708073
  • Text Lang
    ENG
  • ISSN
    2189-0102
  • NDL Article ID
    029097720
  • NDL Call No.
    Z78-A456
  • Data Source
    NDL  J-STAGE 
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