Serotaxonomy of Solanum, Capsicum, Dunalia, and Other Selected Solanaceae

Abstract

Serotaxonomic comparisons were made on about 50 species of Solanaceae. Immunoabsorption data were obtained from reactions of seed protein antigen systems with antibody systems absorbed by several antigen systems in numerous permutations. Relationships of the taxa were computed by newly developed methods. Twenty species of Solanum, mostly of subg. Leptostemonum, were compared using six antisera. Solanum nigrum (subg. Solanum) was serologically distinct from the others. Several groups of species belonging to different sections of Solanum were recognized. Phenetic and phyletic relationships within sect. Androceras were explored. Re-analysis of a complete cubic matrix of immunoabsorption data for eight species of Solanum rearranged relationships slightly but emphasized the divergence between different sections of this genus. A broad survey was made using an antibody system raised to Capsicum annuum. This revealed the distinctiveness of Nicandra from other Solanaceae, several possible inter-generic relationships, but also some unlikely ones. Further studies revealed closer relationships of Dunalia species to Capsicum than to Iochroma. Protein characters are valuable in plant taxonomy for assessing inter-generic and even interfamily relationships (Jensen & Fairbrothers, 1983). Within the Solanaceae several serological studies have been made by workers such as Chester, Hammond, Tucker, Gray, and Lester (see review by Lester, 1979). Because of the complex physico-chemical properties of proteins, and the even more complex phenomena of immunological reactions, many different serotaxonomic techniques have been developed (Jensen & Fairbrothers, 1983). Immunoabsorption resolves subsets of antigenic determinant sites as recognized by corresponding subsets of antibodies after the removal of common antibodies from the antibody system by absorption by other antigen systems. Recent developments in the theoretical and practical aspects of immunoabsorption techniques and the analysis of the resultant data by appropriate numerical taxonomic procedures have been discussed in detail (Lester, 1979; Lester et al., 1983). For this paper these procedures were applied to selected species of Solanaceae. MATERIALS AND METHODS Seed samples from the Birmingham University Solanaceae Collection (Tables 1-3) were used to prepare protein extracts, to induce antibody production in rabbits, and for subsequent immunological experiments using absorbed antibody systems. Procedures, especially the scoring and analysis of results, followed those described by Lester (1979) and Lester et al. (1983). Three sets of experiments were conducted. 1. Twenty accessions of Solanum, mostly of subg. Leptostemonum (Table 1) were compared using six antibody systems (data published in Lester et al., 1983). 2. Eight species from diverse sections of the genus Solanum (Table 2) were compared using eight antibody systems (data published in Lester, 1979). 3. About 25 species of Capsicum, Solanum, and other genera of Solanaceae, mostly of tribe Solaneae (Table 3) were compared using one antibody system (Lester, unpubl. data). Most of these data have now been analyzed by most of the procedures described by Lester et al. (1983), especially by using Jaccard's and similar coefficients to estimate phenetic relationships. Some of the data sets also were subjected to cladistic analysis. Many dendrograms were produced by different analyses of the various sets and subsets of data, some of which are presented herein (Figs. 1-6). I We are grateful to Sarah Marsh for growing these plants, to the Science and Engineering Research Council (U.K.) for financial support, and to Julie Brean, Barbara Klauza, and Sarah Sutton for technical assistance. 2 This paper was part of the Second International Symposium of the Biology and Systematics of the Solanaceae presented at the Missouri Botanical Garden on 3-6 August 1982. 3 Department of Plant Biology, University of Birmingham, Edgbaston, Birmingham B1 5 2TT, England. 4 Department of Nematology, University of California, Riverside, California 92521. ANN. MISSOURI BOT. GARD. 73: 128-133. 1986. This content downloaded from 207.46.13.60 on Thu, 21 Apr 2016 07:28:58 UTC All use subject to http://about.jstor.org/terms 1986] LESTER & ROBERTS-SOLANACEAE SEROTAXONOMY 129 TABLE 1. Listing and classification of the 20 accessions of Solanum species that were compared immunologically using antibody systems to CAP, ROS, SIS, QUT, TOR, and PRN.