Cell and Tissue Culture of Stylosanthes spp.

Abstract

The taxonomically complex genus Stylosanthes (family Leguminosae, subfamily Papilinoidae, tribe Stylosanthinae or Aeschynomeneae) consists of approximately 50, mainly herbaceous species and subspecies (Allen and Allen 1981; ’t Mannetje 1984). Although the genus is native to Central and South America, Stylosanthes species can now be found in the tropical and subtropical regions of the Americas, Africa, Asia, and Australia. Many members of this genus exhibit vigorous growth, a deep-rooting habit, and considerable tolerance to both drought and waterlogging. These species are used as forage crops, as green manure, for soil conservation and as a cover crop in the areas listed above (e.g., Edye et al. 1973; Burt et al. 1980). The most commonly cultivated species is S. guianenis (Aubl.) Sw. (sometimes spelled S. guianensis, see ’t Mannetje (1977) and Burt et al. (1980) for discussions), also known as stylo or Brazilian lucerne. S. guianensis is widely grown in Africa, Asia, Australia, South and Central America, and extensive breeding programs are under way in Australia and, more recently, also in South America. Other economically impartant species are S. capitata, S. erecta, S. gracilis (all Taub.), S. hamata (L.) Taub., S. humilis H.B.K. (also known in Australia as Townsville stylo), S. mucronota Willd., and S. sundaica Taub. The cultivated Stylosanthes species generally have coarse foliage, a tendency to root at the nodes, and often possess profusely nodulated root systems. A rather interesting aspect of the biology of Stylosanthes species (as well as of other members of the Stylosanthinae or Aeschynomeneae such as Arachis and Aeschynomene spp.) is the somewhat unusual process, of rhizobial infection and root nodule development, which proceeds, unlike in other legumes without the formation of infection threads (Chandler et al. 1982; see also review by Meijer and Broughton 1982).