Variation within Stylosanthes sp. aff. scabra and comparison with its closest allies, S. scabra and S. hamata

Abstract

Forty Stylosanthes scabra, S. hamata, and S. sp. aff. scabra lines were grown at CSIRO Lansdown Research Station, North Queensland. Morphological features were grouped with the numerical classification program PATN. Agronomical attributes were recorded and analysed for each group. The resulting 5 groups were largely homogeneous by species. Seed colour, the presence of leaf bristles and stipule horn lateral bristles, stem and inflorescence viscidity, growth habit, and stem length and thickness were important features separating the groups. There were significant differences in yield and seed yield between the groups. Hardseededness ranged from 2 to 79% and the low level of hardseededness in many high-yielding lines is cause for concern. Stylosanthes sp. aff. scabra was found to differ from S. scabra in its narrower and hairless leaves and the presence of stipule horn lateral bristles in combination with a very short or an absent stipule horn terminal bristle. Apart from 1 line, the S. sp. aff. scabra lines fell within 2 groups: a prostrate, low-yielding, anthracnose-susceptible group; and an erect, high-yielding, anthracnose-resistant group. Lines from the second group will be released for commercial use.

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“…Clade 3 is formed by the diploid species S. calcicola, S. macrocarpa, and S. seabrana, all diploid specimens of S. hamata and S. mexicana, some of the tetraploid specimens of S. hamata that we studied, and the tetraploid species S. sundaica. A close relationship between these diploid species and populations is in agreement with both morphological conclusions (Blake 1920, Mohlenbrock 1958, Jansen and Edye 1996) and results of a previous cpDNA sequence analysis (Vander Stappen et al 1999a, Vander Stappen andVolckaert 1999). With the exception of S. seabrana, which is restricted to eastern Brazil, the species of clade 3 have their distribution in the northern Neotropics and/or the mainland of northeastern South America, which corresponds in part to the secondary centre of diversity of the genus.…”

Molecular characterization and phylogenetic utility of the rDNA external transcribed spacer region in Stylosanthes (Fabaceae)

“…With the exception of S. seabrana, which is restricted to Bahia in eastern Brazil, these species occur in the Mexican-Caribbean basin and/ or the mainland of northeastern South America (Mohlenbrock 1958), which corresponds in part to the secondary centre of diversity of the genus. Morphologically they are similar and they are adapted to different environments (Mohlenbrock 1958;Jansen and Edye 1996;Gama López, in preparation). According to Stace and Cameron (1984), these species were primarily distributed in the northern Neotropics, and during the Pleistocene they migrated to the southern Neotropics.…”

Transferência direta de genes para plantas de >i<Stylosanthes guianensis>/i< (Aubl.) Sw.

“…O gênero Stylosanthes compreende aproximadamente 50 espécies e subespécies que são preferencialmente herbáceas. A taxonomia do gênero é complexa e ainda persistem dúvidas quanto à sua filogenia (Curtis et al, 1995;Gillies & Abbott,1996;Glover et al, 1994;Jansen & Edye, 1996;Liu et al, 1996;Vander Stappen et al, 1998;Vieira et al, 1997).…”