Temperature determines the occurrence of CAM or C-3 photosynthesis in pineapple plantlets grown in vitro

Autor(es)

Nievola, C. C. ; Kraus, J. E. ; Freschi, Luciano ^[3] ; Souza, B. M. ; Mercier, H.

• Tipo de documento: Artigo Científico
• Fonte: IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY-PLANT; v. 41, n. 6, p. 832-837, Dec. 2005.
• Área do conhecimento: Ciências Biológicas - Botânica
• Assunto(s): Fruticultura Fotossíntese Abacaxi

Resumo

Ananas comosus (L.) Merr. var. Smooth Cayenne plants when grown in vitro under different temperature regimes developed as CAM or as C-3 plants. The plants used in this study were developed from the lateral buds of the nodal etiolated stem explants cultured on Murashige and Skoog medium for 3 mo. The cultures were maintained under a 16-h photoperiod for different thermoperiods. With 28 degrees C light/15 degrees C dark thermoperiod, as compared with constant 28 degrees C light and dark, pineapple plants had a succulence index two times greater, and also a greater nocturnal titratable acidity and phosphoenolpyruvate carboxylase (PEPCase) activity, indicating CAM-type photosynthesis. The highest abscisic acid (ABA) level occurred during the light period, 8 h prior to maximum PEPCase activity, while the indole-3-acetic acid (IAA) peak was found during the dark period, coinciding with the time of highest PEPCase activity. These plants were also smaller with thicker leaves and fewer roots, but had greater dry weight. Their leaves showed histological characteristics of CAM plants, such as the presence of greater quantities of chlorenchyma and hypoderm. In addition, their vascular system was more conspicuous. In contrast, under constant temperature (28 degrees C light/dark) plants showed little succulence in the leaves. There was no significant acid oscillation and diurnal variation in PEPCase activity in these plants, suggesting the occurrence of C-3 photosynthesis. Also, no diurnal variation in ABA and IAA contents was observed. The results of this study clearly indicate a role for temperature in determining the type of carbon fixation pathway in in vitro grown pineapple. Evidence that ABA and IAA participate in CAM signaling is provided. (AU)

• Processo FAPESP: 03/02677-6 - Variações dos níveis de citocininas durante o ciclo diurno relacionadas com a atividade da redutase do nitrato em raízes de plantas C3 e CAM de abacaxizeiro (Ananas comosus L. Merr.) (Bromeliaceae) cultivadas in vitro
• Beneficiário: Luciano Freschi
• Modalidade de apoio: Bolsas no Brasil - Mestrado