Gomphrena Species (Globe Amaranth): In Vitro Culture and Production of Secondary Metabolites

Abstract

The genus Gomphrena (family Amaranthaceae) comprises approximately 120 species found in the Americas, Australia, and Indo-Malaysia; the most studied species is G. globosa (globe amaranth). Forty-six species occur in Brazil, in savanna vegetation (cerrado), napeadic grassland (campo limpo), high altitude grassland (campo rupestre), and caatinga; only a few species are found in forest. Most species are shrubs or herbs, usually with thickened underground systems of woody (xylopodia) or succulent nature (tuberous roots) (Siqueira 1991). There are numerous weedy species and some cultivated as garden ornamentals. The large purple inflorescences of Gomphrena macrocephala St.-Hil, in contrast to the hairy green leaves, are easily noted in the cerrado vegetation (Fig. 1A). G. globosa L., a tropical annual with white, red, or purple heads (Fig. 2), is grown as an “everlasting” plant (Heywood 1985). This species is also widely used as a test plant for virus propagation and detection, as it grows easily and rapidly and is susceptible to a wide variety of plant viruses, including TMV (tobacco mosaic virus), PVX (potato virus X) and TBRV (tomato black ring virus), (Smith 1974; Matthews 1981; Bos 1983). G. globosa is also a natural virus host (Kitajima and Costa 1966; Brunt et al. 1990) and is known to form spontaneous lesions under high light intensities (Francki 1967).