RESUMO
Global warming leads to increasing irregular and unexpected warm spells during autumn, and therefore natural chilling requirements to break dormancy are at risk. Controlled cold treatment can provide an answer to this problem. Nevertheless, artificial cold treatment will have consequences for carbon reserves and photosynthesis. In this paper, the effect of dark cold storage at 7 °C to break flower bud dormancy in the evergreen Rhododendron simsii was quantified. Carbohydrate and starch content in leaves and flower buds of an early ('Nordlicht'), semi-early ('M. Marie') and late ('Mw. G. Kint') flowering cultivar showed that carbon loss due to respiration was lowest in 'M. Marie', while 'Mw. G. Kint' was completely depleted of starch reserves at the end of cold treatment. Gene isolation resulted in a candidate gene for sucrose synthase (SUS) RsSus, which appears to be homologous to AtSus3 and had a clear increase in expression in leaves during cold treatment. Photosynthesis measurements on 'Nordlicht' and the late-flowering cultivar 'Thesla' showed that during cold treatment, dark respiration decreased 58% and 63%, respectively. Immediately after cold treatment, dark respiration increased and stabilised after 3 days. The light compensation point followed the same trend as dark respiration. Quantum efficiency showed no significant changes during the first days after cold treatment, but was significantly higher than in plants with dormant flower buds at the start of cold treatment. In conclusion, photosynthesis stabilised 3 days after cold treatment and was improved compared to the level before cold treatment.
Assuntos
Fotossíntese/fisiologia , Rhododendron/fisiologia , Aclimatação , Metabolismo dos Carboidratos , Carbono/metabolismo , Respiração Celular , Temperatura Baixa , Escuridão , Flores/genética , Flores/fisiologia , Flores/efeitos da radiação , Genótipo , Luz , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Rhododendron/genética , Rhododendron/efeitos da radiação , Estações do Ano , Amido/metabolismo , TranscriptomaAssuntos
Actinomycetaceae/isolamento & purificação , Infecções por Actinomycetales/microbiologia , Prostatite/microbiologia , Pielonefrite/microbiologia , Sepse/microbiologia , Actinomycetaceae/patogenicidade , Infecções por Actinomycetales/urina , Bacteriemia/microbiologia , Bacteriúria/microbiologia , Reações Falso-Negativas , Humanos , Contagem de Leucócitos , Masculino , Prostatite/urina , Pielonefrite/urina , Kit de Reagentes para Diagnóstico , Sepse/urina , Simbiose , Urina/citologiaRESUMO
Flower bud dormancy in azalea (Rhododendron simsii) is broken by artificial cold treatment and this will have its consequences on carbon reserves and photosynthesis. The effect of cold storage at 7 °C on carbohydrate and starch content in leaves and flower buds of an early ('Nordlicht') and semi-early ('M. Marie) flowering cultivar was quantified. Carbon loss due to respiration was lowest for 'M. Marie'. Photosynthetic measurements on 'Nordlicht' showed that photosynthesis 3 days after cold treatment (plants ready to flower) was improved compared to before cold treatment (plants with dormant flower buds).