Morphological characteristics and cell viability of coffee plants calli/Caracteristicas morfologicas e viabilidade celular de calos de cafeeiro

The aim of this research was to characterize and compare two types of cadi from leaf explants of Coffea arabica (cultivar Catigua). Cells of different types of callus were successfully characterized regarding viability and internal and external morphological characteristics. It was obtained two morphologically distinct types of callus: (i) yellow friable and (ii) transparent watery. The yellow friable calli showed higher cell viability and embryogenic characteristics. Scanning and transmission electron microscopy showed embryogenic characteristics in cells of the yellow friable calli evidenced by the presence of small and isodiametric cells, while transparent watery calli showed elongated cells and large cytoplasm vacuolization. Key words: Coffea arabica, electron microscopy, tetrazolium test. O objetivo deste trabalho foi caracterizar e comparar dois tipos de calos de explantes foliares de Coffea arabica (cultivar Catigua). Celulas de diferentes tipos de calos foram caracterizadas quanto a viabilidade e caracteristicas morfologicas externas e internas. Foram obtidos dois tipos de calos morfologicamente distintos: (a) amarelo friavel e (b) transparente aquoso. Os calos amarelos friaveis apresentaram maior viabilidade celular e caracteristicas embriogenicas. Microscopia eletronica de varredura e transmissao mostraram caracteristicas embriogenicas em calos amarelos friaveis evidenciadas pela presenca de celulas pequenas e isodiametricas. Os calos transparentes aquosos apresentaram celulas alongadas e vacuolizadas. Palavras-chave: Coffea arabica, microscopia eletronica, teste do tetrazolio.