The Analysis of Variance.

All else being equal, polyploids are expected to have larger C-values (amount of DNA in the unreplicated gametic nucleus) than their diploid progenitors, increasing in direct proportion with ploidy. This expectation is observed in some polyploid series, especially those newly formed, but there are examples suggesting that C-values in particular polyploids are less than expected. The availability of the Angiosperm DNA C-values database (http:// www.rbgkew.org.uk/cvavhomepage.html) has allowed this question to be addressed across a broad range of angiosperms and has revealed striking results deviating from expectation: (i) mean 1C DNA amount did not increase in direct proportion with ploidy, and (ii) mean DNA amount per basic genome (calculated by dividing the 2C value by ploidy) tended to decrease with increasing ploidy. These results suggest that loss of DNA following polyploid formation, or genome downsizing, may be a widespread phenomenon of considerable biological significance. Recent advances in our understanding of the molecular events that take place following polyploid formation together with new data on how DNA amounts can both increase and decrease provide some insights into how genome downsizing may take place. The nature of the evolutionary forces that may be driving DNA loss are also discussed.

Genome downsizing in polyploid plants

The Prosopis juliflora - Prosopis pallida complex: a monograph

The Leguminosae, the third-largest angiosperm family, has a global distribution and high ecological and economic importance We examine how the legume systematic research community might join forces to produce a comprehensive phylogenetic estimate for the ca 751 genera and ca 19,500 species of legumes and then translate it into a phylogeny-based classification We review the current state of knowledge of legume phylogeny and highlight where problems lie, for example in taxon sampling and phylogenetic resolution We review approaches from bioinformatics and next-generation sequencing, which can facilitate the production of better phylogenetic estimates Finally, we examine how morphology can be incorporated into legume phylogeny to address issues in comparative biology and classification Our goal is to stimulate the research needed to improve our knowledge of legume phylogeny and evolution; the approaches that we discuss may also be relevant to other species-rich angiosperm clades

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Legume phylogeny and classification in the 21st century: Progress, prospects and lessons for other species-rich clades

Genome Size Variation and Plant Systematics

Hybridization and genetic variation of Argentine species of Prosopis

A study of nuclear DNA content was made in telophase nuclei (2C) of the root apex of germinating seed in nine populations of the following species and cytotypes of Larrea: L. nitida (2x), L. divaricata (2x), L. cuneifolia (4x) and L. tridentata (2x, 4x, 6x). There were no significant differences in DNA content per basic monoploid genome among the diploid taxa nor between the latter and the tetraploid, among tetraploids or between tetraploids and the hexaploid. On the other hand, the difference between means was significant when all diploids were compared with the hexaploid cytotype. These results would indicate: (1) Speciation at the diploid level in Larrea has not produced great differences in DNA content per basic genome. This is in contrast with the related genus Bulnesia. (2) In Larrea there is a slight diminution in DNA content per basic genome when there is an increase in ploidy level. (3) Species of Larrea, Bulnesia and Pintoa (Zygophyllaceae) that inhabit the most arid environments are the ones possessing the highest DNA content. (4) This increase is due to an increment in ploidy level in Larrea and an augment of intrachromosomal DNA in Bulnesia and Pintoa.

/pdf/nuclear-dna-variation-in-diploid-and-polyploid-taxa-of-4ys6u4dzkv.pdf

Nuclear DNA variation in diploid and polyploid taxa of Larrea (Zygophyllaceae)

A polymorphic population of Phaseolus vulgaris L. var. aborigineus (Burkart) Baudet growing in northwestern Argentina was studied. In order to know the origin of this polymorphism, plants belonging to the var. aborigineus, others showing floral dimorphism and individuals with weedy type characters were collected. Their seeds, obtained after fieldwork treatments of autogamy and free pollination in order to know their reproductive system, were sown in a greenhouse. Information of their growth was recorded and several numerical analyses were performed. With the results obtained, we concluded that those individuals that showed floral dimorphism are probably a result of hybridization and/or introgression between the var. aborigineus and cultivated forms that grow in the area. This hypothesis is supported by the presence of divergent segregation in the offspring. Also, the offspring of the F1 was followed and allowed us to conclude the possible existence of degeneration of the hybrid progeny. This degeneration indicates that an unwanted gene flow in the area could lead to a decline in the wild bean population. The vigour and high reproductive success of the offspring belonging to the individuals corresponding to the var. aborigineus, whose progenitor was treated for outcrossing, and the existence of plants with weedy type characteristics, are indicative of the necessity to preserve this germplasm in order to evaluate its agronomic potential as brief as possible. The population here studied constitutes a wild-weed–crop complex growing in Argentina.

Hybridization Between Wild and Domesticated Types of Phaseolus vulgaris L. (Fabaceae) in Argentina

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1096-0031.2006.00140.x

Phylogeny of Macroptilium (Leguminosae): morphological, biochemical and molecular evidence

Prosopis L. is a rather primitive genus within the Leguminosae–Mimosoideae. This genus has been divided into five sections on the basis especially of the vegetative diversification of the spines. Three of the sections, Algarobia, Monilicarpa and Strombocarpa, are distributed in America. In order to elucidate systematic relationships between the American sections of Prosopis, a morphological and biochemical phylogeny were obtained. Twenty-two morphological characters were scored for 27 species of Prosopis and the outgroup taxon following polyacrilamide gel electrophoresis of seed storage proteins. The results obtained clearly prove that the secction Strombocarpa is a natural taxon. The section Algarobia, on the other hand, seems to comprise an artificial grouping of species. Members of the series Denudantes appear isolated from the remaining species, therefore this taxon should be treated as a new section within Prosopis. The section Algarobia should be circumscribed to series Chilenses, Ruscifoliae and Pallidae, which are always united in a monophyletic clade. Finally, no evidence was found to confirm the existence of the section Monilicarpa.

Alicia Diana Burghardt

Papers

Hybridization and genetic variation of Argentine species of Prosopis

Nuclear DNA variation in diploid and polyploid taxa of Larrea (Zygophyllaceae)

Hybridization Between Wild and Domesticated Types of Phaseolus vulgaris L. (Fabaceae) in Argentina

Phylogeny of Macroptilium (Leguminosae): morphological, biochemical and molecular evidence

Phylogeny of Prosopis (Leguminosae) as shown by morphological and biochemical evidence