Oxalis

Abstract: Aim We tested the relative vulnerability of islands to Oxalis pes-caprae L. invasion compared to mainland regions. Oxalis pes-caprae is a South African annual geophyte that reproduces via bulbils, and has spread in many Mediterranean and temperate regions of the world where introduced. Our study is one of the first detailed regional analyses of the occurrence and local abundance of a non-native plant. Methods We conducted an extensive survey (2000 sampling points) to examine local and coarse-scale patterns in both the occurrence and abundance of O. pes-caprae on islands and in neighbouring mainland regions of Spain. Location We analysed occurrence (number of samples where present) and abundance (percentage cover) on two Balearic Islands (Menorca and Mallorca)

Abstract: In continuing study of the origins of the octoploid tuber crop oca, Oxalis tuberosa Molina, we used phylogenetic analysis of DNA sequences of the chloroplast-active (nuclear encoded) isozyme of glutamine synthetase (ncpGS) from cultivated oca, its allies in the "Oxalis tuberosa alliance," and other Andean Oxalis Multiple ncpGS sequences found within individuals of both the cultigen and a yet unnamed wild tuber-bearing taxon of Bolivia were separated by molecular cloning, but some cloned sequences appeared to be artifacts of polymerase chain reaction (PCR) recombination and/or Taq error Nonetheless, three classes of nonrecombinant sequences each joined a different part of the O tuberosa alliance clade on the ncpGS gene tree Octoploid oca shares two sequence classes with the Bolivian tuber-bearing taxon (of unknown ploidy level) Fixed heterozygosity of these two sequence classes in all ocas sampled suggests that they represent homeologous loci and that oca is allopolyploid A third sequence class, found in eight of nine oca plants sampled, might represent a third homeologous locus, suggesting that oca may be autoallopolyploid, and is shared with another wild tuber-bearing species, tetraploid O picchensis of southern Peru Thus, ncpGS data identify these two taxa as the best candidates as progenitors of cultivated oca

Abstract: As part of a study aimed at elucidating the origins of the octoploid tuber crop "oca," Oxalis tuberosa, DNA sequences of the internal trancribed spacer of nuclear ribosomal DNA (nrDNA ITS) were determined for oca and several wild Oxalis species, mostly from Bolivia. Phylogenetic analysis of these data supports a group of these species as being close relatives of oca, in agreement with morphology and cytology, but at odds with traditional infrageneric taxonomy. Variation in ITS sequences within this group is quite low (0-7 substitutions in the entire ITS region), contrasting with the highly divergent (unalignable in some cases) sequences within the genus overall. Some groups of morphologically differentiated species were found to have identical sequences, notably a group that includes oca, wild populations of Oxalis that bear small tubers, and several other clearly distinct species. The presence of a second, minor sequence type in at least some oca accessions suggests a possible contribution from a second genome donor, also from within this same species group. ITS data lack sufficient variation to elucidate the origins of oca precisely, but have identified a pool of candidate species and so can be used as a tool to screen yet unsampled species for possible progenitors.