Developing a model system in vitro to understand tracheary element development in douglas-fir ("Peudostuga mensziesii")

• Autores: Karthik V. Pillai, Armando G. Mcdonald, Francis G. Wagner
• Localización: Maderas: Ciencia y tecnología, ISSN 0717-3644, ISSN-e 0718-221X, Vol. 13, Nº. 1, 2011, págs. 3-18
• Idioma: inglés
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• Resumen

  • Callus cells were initiated on cambial strips obtained from 4 to 8 y old Douglas-fir (Pseudostugamenziesii) trees, cultured on solidified Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxyaceticacid (2,4-D) and benzylaminopurine (BA). The cultures could be maintainedby sub-culturing on fresh medium every four weeks. When the callus cells were subsequentlytransferred to liquid MS medium supplemented with different phytohormones, suspension culturescould be initiated and maintained by periodic sub-culture. Approximately 65% of the callus cellscultured on liquid MS medium supplemented with 2,4-D, when maintained for 6-7 weeks withoutsub-culture, differentiated to tracheary element (TE) like cells. The formation of TE like cells wasconfirmed histochemically by staining with phloroglucinol-HCl. Secondary thickening of the cellwalls were confirmed by polarized light microscopy, which showed strong birefringence of the cellwall due the presence of crystalline cellulose. The presence of lignin was determined by pyrolysis-GC-MS and FTIR spectroscopy. The lignin content in differentiated cell wall samples was quantifiedat 21% by the lignothioglycolic acid assay. Analysis of monosaccharide composition of cell wallsamples after acid hydrolysis showed that the percentage of glucose, xylose and mannose hadincreased in the differentiated cell walls. These increases correspond to the formation of cellulose,glucomannan and xylan, primarily associated with secondary cell walls.