Helmut Freitag

Phylogeny of Amaranthaceae and Chenopodiaceae and the Evolution of C4 Photosynthesis

A phylogenetic analysis of Chenopodiaceae and Amaranthaceae was carried out using sequence variation of the chloroplast gene rbcL. Our sampling included 108 species of these two families along with 29 species of Caryophyllales serving as outgroups. Phylogeny inferences with maximum parsimony and maximum likelihood indicate that the two families form a well‐supported monophyletic clade that is sister to Achatocarpaceae. Despite extensive sampling, we found that the relationship between Chenopodiaceae and Amaranthaceae remains unclear as a result of short and weakly supported basal branches. The clearly monophyletic Polycnemoideae (traditionally considered a subfamily of Chenopodiaceae) appear as sister to Amaranthaceae sensu stricto. Within Amaranthaceae, most major lineages inferred except Gomphrenoideae and Celosieae do not correspond to recognized subfamilies and tribes. Bosea and Charpentiera branch first in the Amaranthaceae. Within Chenopodiaceae, the genera of Betoideae occur in basal and largely unresolved positions. The remaining Chenopodiaceae are divided into three major clades of unclear relationship: Chenopodioideae (Atripliceae s.str., Chenopodieae I‐III); Corispermoideae (Corispermeae); and Salicornioideae (Haplopeplideae, Salicornieae), Suaedoideae (Suaedeae, Bienertieae), and Salsoloideae (Camphorosmeae, Sclerolaeneae, Salsoleae I‐II). The rbcL tree is discussed also with regard to historical classifications and morphological support for the major clades. The molecular results are used to elucidate the evolution of C4 photosynthesis in the two families. C4 photosynthesis has evolved independently at least three times in Amaranthaceae and at least 10 times in Chenopodiaceae. A survey of C4 leaf anatomy revealed 17 different leaf types that in most cases mark an independent origin of C4 photosynthesis. The application of a molecular clock indicates an age of C4 photosynthesis of 11.5–7.9 Ma in Atriplex (Chenopodioideae) and 21.6–14.5 Ma in subfamily Salsoloideae.

An integrated molecular and morphological study of the subfamily Suaedoideae Ulbr. (Chenopodiaceae)

Abstract.As part of an ongoing project on the phylogeny and taxonomy of Chenopodiaceae with emphasis on the evolution of photosynthetic pathways, we sequenced the nuclear ribosomal ITS region and two chloroplast DNA regions (atpB-rbcL and psbB-psbH) of 43 taxa belonging to subfamily Suaedoideae (Chenopodiaceae). Our sampling covered 41 of c. 82 known species and subspecies of Suaeda, beside several taxa not yet described, the monotypic genera Bienertia and Borszczowia as well as some representatives of Salicornioideae that served as outgroups. In addition, we carried out morphological and leaf anatomical studies on an extended sampling set, also including the monotypic genus Alexandra. Phylograms resulting from maximum parsimony analyses of separate and combined data sets share several common features. (1) Suaeda is monophyletic if Borszczowia is included. (2) The position of Bienertia is ambiguous, being sister to Suaeda in both chloroplast trees, but showing affinities to Salicornioideae in the ITS tree. (3) Suaeda deeply divides into two well-supported clades. One clade (Brezia clade) solely consists of the annual C3 species of sect. Brezia. The second clade (Suaeda clade) includes all other sections. (4) The subclades of the Suaeda clade are in general agreement with currently accepted sections. A reassessment of morphological and anatomical characters on the background of the molecular trees resulted in the recognition of pistil morphology and leaf type as key characters. All major molecular clades are precisely defined by characteristic combinations of pistil and leaf types. The following taxonomic conclusions are drawn: the status of Bienertieae Ulbr. is confirmed; Suaeda is subdivided into the new subgenera Brezia (Moq.) Freitag & Schütze and Suaeda;Borszczowia is recombined into Suaeda and given sectional rank; within Suaeda, sects. Brezia, Schanginia, Borszczowia, Suaeda, Physophora, Schoberia and Salsina are recognized with some changes in circumscription; Alexandra is maintained at generic level because of the lack of molecular data and its striking morphological differences from Suaeda. A conspectus of Suaedoideae containing recognized species and all supraspecific taxa is given. The molecular results confirm that C4 photosynthesis has evolved independently four times in the subfamily.

Phylogeny of Salicornioideae (Chenopodiaceae): diversification, biogeography, and evolutionary trends in leaf and flower morphology

Chenopodiaceae-Salicomioideae (14-16 gen./c. 90 spp.) are distributed worldwide in coastal and inland saline habitats. Most of them are easy to recognize by their succulent-articulated stem with strongly reduced leaves and by flowers aggregated in dense, thick spike-shaped thyrses. ITS and the atpB-rbcL spacer were sequenced for 67 species representing 14 genera of Salicomioideae and analysed with maximum parsimony and maximum likelihood, a fossil-calibrated molecular clock using the penalized likelihood method, and lineage through time plots. The evolution of stem, leaf, and flower morphology was traced using MacClade. Both molecular markers indicate that the monophyletic Salicomioideae originated in Eurasia during the Late Eocene/Early Oligocene (38.2- 28.7 Mya) and experienced a rapid radiation into its major lineages during the Early Oligocene with Allenrolfea/Heterostachys, Kalidium, Halopeplis and Halocnemum/Halostachys branching off early. Already in the Middle Miocene (19.6-14.6 Mya) all major lineages of Salicornioideae were present. These additionally include Arthrocnemum/Microcnemum, the Halosarcia lineage (which includes all Australian species except for the Australian Sarcocornia) and the Salicornia/Sarcocornia lineage. A high intercontinental dispersability can be observed in Salicomioideae in particular in the Salicornia/Sarcocornia lineage with multiple colonization events in America, Australia and South Africa linked to the global aridification during the Oligocene, Late Miocene and Pliocene. The comparatively low species number of many genera is explained by a low number of niches present in the extreme habitats of Salicomioideae, strong interspecific competition mainly by close relatives, and by Pleistocene extinctions. We detected an evolutionary trend towards increasing reduction of the leaf lamina in Salicomioideae, with an ovate or terete leaf with a decurrent base as the plesiomorphic condition. Opposite phyllotaxis has arisen at least two times in the subfamily and is strongly correlated with the pair-wise fusion of leaves (not bracts), the reduction of leaf lamina, and the articulation of stem. However, the articulated stems and reduced leaves also have evolved twice in lineages with alternate phyllotaxis, such as Allenrolfea and Kalidium caspicum. Only one shift from free to connate bracts occurred in Salicomioideae with at least one reversal within the Halosarcia lineage. The fusion of bracts is mostly accompanied by a partly or fully connation of bracts and axis resulting in club-shaped spikes in which the flowers are tightly embedded in cavities. Both molecular trees are conflicting with the traditional tribes indicating that their diagnostic characters have originated by convergent evolution. For reasons of stability and clarity we propose that only one tribe, Salicomieae, should be recognized. The traditional circumscription of most genera is supported by the molecular results except for the closely related genera of the Australian Halosarcia clade and the Sarcocornia/Salicornia complex. The monotypic Kalidiopsis clearly originated from within Kalidium, and it is therefore newly combined in Kalidium.

A taxonomic nightmare comes true: phylogeny and biogeography of glassworts (Salicornia L., Chenopodiaceae)

In this study we analysed ETS sequence data of 164 accessions belonging to 31 taxa of Salicornia, a widespread, hygrohalophytic genus of succulent, annual herbs of Chenopodiaceae subfam. Salicornioideae, to investigate phylogenetic and biogeographical patterns and hypothesise about the processes that shaped them. Furthermore, our aim was to understand the reasons for the notorious taxonomic difficulties in Salicornia. Salicornia probably originated during the Miocene somewhere between the Mediterranean and Central Asia from within the perennial Sarcocornia and started to diversify during Late Pliocene/Early Pleistocene. The climatic deterioration and landscape-evolution caused by orogenetic processes probably favoured the evolution and initial diversification of this annual, strongly inbreeding lineage from the perennial Sarcocornia that shows only very limited frost tolerance. The further diversification of Salicornia was promoted by at least five intercontinental dispersal events (2 x to South Africa, at least 3 x to North America) and at least two independent polyploidization events resulting in rapidly expanding tetraploid lineages, both of which are able to grow in lower belts of the saltmarshes than their diploid relatives. The diploid lineages of Salicornia also show rapid and effective range expansion resulting in both widespread genotypes and multiple genotypes in a given area. Reproductive isolation through geographical isolation after dispersal, inbreeding, and comparatively young age might be responsible for the large number of only weakly differentiated lineages. The sequence data show that the taxonomic confusion in Salicornia has two major reasons: (1) in the absence of a global revision and the presence of high phenotypic plasticity, the same widespread genotypes having been given different names in different regions, and (2) striking morphological parallelism and weak morphological differentiation led to the misapplication of the same name to different genotypes in one region.

Contributions to the chenopod flora of Egypt

Summary Additions to the chenopod flora of Egypt are made on base of recent collections done by the author in Lower Egypt and N Sinai, and by B ornkamm and Kehl in NW and W Egypt. They were completed by studies in Cairo herbarium (CAI), and for some taxa by investigation of type material. Many new localities contribute to the better knowledge of the respective distributional pattern, and remarks on the ecology and representation of species in different plantcommunities are given. Several species are recorded for the first time for the mainland of Egypt, e.g. Salsola cyclophylla, S. spinescens and Suaeda palaestina. In many cases critical taxonomic remarks are made, several species described by F orsskal are typified, and new keys for the Egyptian species of the genera Suaeda and Salsola are presented.

C3 and C4 leaf anatomy types in Camphorosmeae (Camphorosmoideae, Chenopodiaceae)

Complementary to our previous project on the molecular phylogeny of Camphorosmeae, the leaf anatomy of ca. 35 species including all non-Australian and selected Australian species was studied by use of light microscopy. Nine anatomical leaf types were described, compared to previous classifications, and discussed with regard to their putative evolution on the background of phylogenetic trees. Particular emphasis was given to the relationships between the C3 and C4 leaf types: Chenolea type (C3), Eokochia type (C3), Neokochia type (C3), Sedobassia type (C3/C4 intermediate), Bassia prostrata type (C4), B. muricata type (C4), B. eriantha type, B. lasiantha type (C4), Camphorosma type (C4). The main results and conclusions were: (1) Two unusual new C3 leaf types: Chenolea with microfenestrate chlorenchyma, Eokochia with unique complex vascular bundles; (2) Sedobassia interpreted as anatomically C3/C4 intermediate by kranz-like bundle sheath cells is the first C3/C4 intermediate in Camphorosmeae and found in a derived position; (3) Neokochia type detected as the likely starting point for all four C4 leaf types and for the C3/C4 intermediate; (4) hypodermis of C4 types originated from outermost chlorenchyma layer of C3 types and lost multiple times during further evolution; (5) atriplicoid Bassia. lasiantha type without water storage tissue evolved from kochioid B.muricata type; (6) two independent gains of C4 photosynthesis, one in Bassia and one in Camphorosma; (7) depending on the lineage, leaf architecture remains comparatively stable (Australian Camphorosmeae) or shows an unexpected plasticity (Bassia scoparia group).

THE EPHEDRA-SPECIES OF P. FORSSKAL: IDENTITY AND TYPIFICATION

Summary The names of the two Ephedra-species validly published in P. ForsskAls Flora aegyptiaco-arabica are typified: E. aphylla Forssk. by means of a neotype, and E. foeminea Forssk. by designation of a lectotype. Arguments and details in support of the decisions are provided. Hitherto, E. aphylla has usually been called E. alte C. Meyer. The type material of the later published E. alte is in fact a mixture of E. aphylla (male specimens) and E. foliata Boiss. ex C. Meyer (female specimens). Ephedrafoeminea also has priority against E. campylopoda C. Meyer. The species and their closer relatives are compared with respect to their morphology, ecology and distribution.

When do different C4 leaf anatomies indicate independent C4 origins? Parallel evolution of C4 leaf types in Camphorosmeae (Chenopodiaceae)

Broad-scale phylogenetic studies give first insights in numbers, relationships, and ages of C4 lineages. They are, however, generally limited to a model that treats the evolution of the complex C4 syndrome in different lineages as a directly comparable process. Here, we use a resolved and well-sampled phylogenetic tree of Camphorosmeae, based on three chloroplast and one nuclear marker and on leaf anatomical traits to infer a more detailed picture of C4 leaf-type evolution in this lineage. Our ancestral character state reconstructions allowed two scenarios: (i) Sedobassia is a derived C3/C4 intermediate, implying two independent gains of C4 in Bassia and Camphorosma; or (ii) Sedobassia is a plesiomorphic C3/C4 intermediate, representing a syndrome ancestral to the Bassia/Camphorosma/Sedobassia lineage. In Bassia, a kochioid leaf type (Bassia muricata and/or Bassia prostrata type) is ancestral. At least three independent losses of water-storage tissue occurred, resulting in parallel shifts towards an atriplicoid leaf type. These changes in leaf anatomy are adaptations to different survival strategies in steppic or semi-desert habitats with seasonal rainfall. In contrast, Camphorosma shows a fixed C4 anatomy differing from Bassia types in its continuous Kranz layer, which indeed points to an independent origin of the full C4 syndrome in Camphorosma, either from an independent C3 or from a common C3/C4 intermediate ancestor, perhaps similar to its C3/C4 intermediate sister genus Sedobassia. The enlarged bundle sheath cells of Sedobassia might represent an important early step in C4 evolution in Camphorosmeae.

Molecular phylogeny and forms of photosynthesis in tribe Salsoleae (Chenopodiaceae)

Abstract While many C4 lineages have Kranz anatomy around individual veins, Salsoleae have evolved the Salsoloid Kranz anatomy where a continuous dual layer of chlorenchyma cells encloses the vascular and water‐storage tissue. With the aim of elucidating the evolution of C4 photosynthesis in Salsoleae, a broadly sampled molecular phylogeny and anatomical survey was conducted, together with biochemical, microscopic, and physiological analyses of selected photosynthetic types. From analyses of photosynthetic phenotypes, a model for evolution of this form of C4 was compared with models for evolution of Kranz anatomy around individual veins. A functionally C3 proto‐Kranz phenotype (Proto‐Kranz Sympegmoid) and intermediates with a photorespiratory pump (Kranz‐like Sympegmoid and Kranz‐like Salsoloid types) are considered crucial transitional steps towards C4 development. The molecular phylogeny provides evidence for C3 being the ancestral photosynthetic pathway but there is no phylogenetic evidence for the ancestry of C3‐C4 intermediacy with respect to C4 in Salsoleae. Traits considered advantageous in arid conditions, such as annual life form, central sclerenchyma in leaves, and reduction of surface area, evolved repeatedly in Salsoleae. The recurrent evolution of a green stem cortex taking over photosynthesis in C4 clades of Salsoleae concurrent with leaf reduction was probably favoured by the higher productivity of the C4 cycle.

Suaeda corniculata (Chenopodiaceae) and related new taxa from Eurasia

Abstract Lomonosova, M., Brandt, R. & Freitag, H.: Suaeda corniculata (Chenopodiaceae) and related new taxa from Eurasia. — Willdenowia 38: 81–109. — ISSN 0511-9618;