No abstract

The online resource http://www.plantrdnadatabase.com/ stores information on the number, chromosomal locations and structure of the 5S and 18S-5.8S-26S (35S) ribosomal DNAs (rDNA) in plants. This resource was exploited to study relationships between rDNA locus number, distribution, the occurrence of linked (L-type) and separated (S-type) 5S and 35S rDNA units, chromosome number, genome size and ploidy level. The analyses presented summarise current knowledge on rDNA locus numbers and distribution in plants. We analysed 2949 karyotypes, from 1791 species and 86 plant families, and performed ancestral character state reconstructions. The ancestral karyotype (2n = 16) has two terminal 35S sites and two interstitial 5S sites, while the median (2n = 24) presents four terminal 35S sites and three interstitial 5S sites. Whilst 86.57% of karyotypes show S-type organisation (ancestral condition), the L-type arrangement has arisen independently several times during plant evolution. A non-terminal position of 35S rDNA was found in about 25% of single-locus karyotypes, suggesting that terminal locations are not essential for functionality and expression. Single-locus karyotypes are very common, even in polyploids. In this regard, polyploidy is followed by subsequent locus loss. This results in a decrease in locus number per monoploid genome, forming part of the diploidisation process returning polyploids to a diploid-like state over time.

Taxonomic complexity has hindered the partitioning of the arti®cial genus Centaurea, even though it has long been recognized as a polyphyletic assemblage. On the basis of morphology, pollen type, karyology and DNA sequence analysis, previous workers have de®ned ®ve informal groups in the genus (Acrocentron, Centaurea sensu stricto, Cyanus, Jacea and Psephellus). However, the precise delimitation of these groups and their relationships remain largely unknown. Moreover, although some informal groups have been established among the rest of the subtribe (Amberboa, Carthamus and Stemmacantha), many genera cannot be classi®ed in any group. Newer molecular approaches are essential for resolving these problems. Sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA and the chloroplast gene matK were analysed for a comprehensive sample of the whole subtribe, with the aim of clarifying the delimitation and the phylogeny of the groups of the Centaureinae. Results largely con®rm the suggested informal entities as natural groups, with some interesting changes of placement of some genera, especially in the Acrocentron and the Stemmacantha groups. Our results con®rm that the sections of Centaurea with Dealbata pollen type should be classi®ed as a dierent genus, Psephellus. In addition to morphology and suggested pollen type evolution, the ITS and matK phylogenies are also supported by karyological evidence. Our results con®rm that the natural delimitation of Centaurea that minimizes nomenclatural changes is possible only if a new type of the genus is designated.

The Millennium Ecosystem Assessment found a general decline in the consumption and gathering of wild edible 31 plants, but some studies also observe a localized increase. Using information from interviews (n = 1133) in seven 32 sites in the Iberian Peninsula and one in the Balearic Islands, we 1) identify current trends in the consumption and 33 gathering of wild edible plants (n = 56 plant-uses) and 2) analyze how cultural ecosystem services relate to such 34 trends. Our data show a generalized decrease in the consumption and gathering of wild edible plants, although 35 the trend changes significantly across plant-uses. Specifically, we found that -despite the overall decreasing 36 trend-uses of wild edible plants that simultaneously relate to foods with high cultural appreciation and the 37 recreational function of gathering remain popular. Our results signal that cultural services and values associated 38 to the gathering and consumption of some wild edible plants are important factors explaining divergent trends 39 across plant species. This finding reinforces the notion that cultural ecosystem services are deeply intertwined 40 with other categories of services which can combine in complex, non-linear ways producing a variety of 41 interdependent benefits. 42

No abstract

Sequences of the internal transcribed spacers (ITS1 and ITS2) of nuclear ribosomal DNA were analysed for 44 Artemisia species (46 populations) representing all the five classical subgenera and the geographical range of the genus, 11 species from 10 genera closely related to Artemisia, and six outgroup species from five other genera of the Anthemideae. The results definitely support the monophyly of the genus Artemisia in its broadest sense (including some Hippolytia, Kaschgaria). Our results, correlated to other data, such as pollen morphology, allow us to conclude that the subtribe Artemisiinae as currently defined is a very heterogeneous group. Affinities of the largest genus of the subtribe and tribe, Artemisia, and of other genera of the subtribe to some genera from other subtribes of the Anthemideae strongly suggest that subtribe Artemisiinae needs a deep revision and redefinition. Phylogenetic utility of region trnL-F of the plastid DNA in the genus Artemisia and allies was also evaluated; sequences of the trnL-F region in Artemisia do not provide phylogenetic information.

No abstract

No abstract