Ancient Gondwana break-up explains the distribution of the mycoheterotrophic family Corsiaceae (Liliales)

Plant science

Veratrum album and Veratrum nigrum (Melianthaceae) in Italy. Micromorphology and Systematics

The investigation of some populations of Veratrum album and V. nigrum showed intermediate forms that can be refered to possible cross between these two species

MOLECULAR SYSTEMATICS OF IRIDACEAE: A COMBINED ANALYSIS OF FOUR PLASTID DNA SEQUENCE MATRICES

Iridaceae are one of the largest families of Lilianae and probably also among the best studied families of monocotyledons. To further evaluate generic, tribal and subfamilial relationships, we have produced four plastid DNA data sets for 57 genera of Iridaceae plus outgroups: rps4, rbcL (both protein coding genes), and the trnL intron snd the trnL-F inter-gene spacer. All four matrices produce highly congruent, although not identical trees, and we thus analysed them in a combined analysis, which produced a highly resolved and well supported topology. In each of the individual trees, some genera or groups of genera are misplaced relative to Goldblatt’s and Rudall’s morphological cladistic studies, but the combined analysis produced a pattern much more similar to these previous ideas of relationships. In the combined tree, all subfamilies were resolved as monophyletic clades, except Nivenioideae, which formed a grade in which Ixioideae were embedded. The achlorophyllous Geosiris (sometimes referred to Geosiridaceae or Burmanniaceae) fell within the nivenioid grade. Most of the tribes are monophyletic, except for Ixieae, Watsonieae and Sisyrinchieae, but the topology within Ixioideae is not strongly supported due to extremely low levels of sequence divergence. Isophysis is sister to the rest of the family, and Diplarrhena falls in a well supported position as sister to Irideae/Sisyrinchieae/Tigridieae/Mariceae; Bobartia of Sisyrinchieae is supported as a member of Irideae

Morphological diversity and evolution of Centrolepidaceae (Poales), a species-poor clade with diverse body plans and developmental patterns.

PREMISE OF THE STUDY: The small primarily Australian commelinid monocot family Centrolepidaceae displays remarkably high structural diversity that has been hitherto relatively poorly explored. Data on Centrolepidaceae are important for comparison with other Poales, including grasses and sedges. METHODS: We examined vegetative and reproductive morphology in a global survey of Centrolepidaceae based on light and scanning electron microscopy of 18 species, representing all three genera. We used these data to perform a cladistic analysis to assess character evolution. KEY RESULTS: Each of the three genera is monophyletic; Centrolepis is sister to Aphelia. Some Centrolepidaceae show a change from spiral to distichous phyllotaxy on inflorescence transition. In Aphelia and most species of Centrolepis, several morphologically distinct leaf types develop along the primary shoot axis and flowers are confined to dorsiventral lateral spikelets. Centrolepis racemosa displays secondary unification of programs of leaf development, absence of the leaf hyperphyll and loss of shoot dimorphism. Presence or absence of a leaf ligule and features of inflorescence and flower morphology are useful as phylogenetic characters in Centrolepidaceae. CONCLUSIONS: Ontogenetic changes in phyllotaxy differ fundamentally between some Centrolepidaceae and many grasses. Inferred evolutionary transformations of phyllotaxy in Centrolepidaceae inflorescences also differ from those in grasses. In contrast with grasses, some Centrolepidaceae possess ligulate leaves where the ligule represents the boundary between the bifacial hypophyll and unifacial hyperphyll. All the highly unusual features of the morphological-misfit species Centrolepis racemosa could result from the same saltational event. Centrolepidaceae offer good perspectives for studies of evolutionary developmental biology.Dmitry D. Sokoloff, Margarita V. Remizowa, Matthew D. Barrett, John G. Conran, and Paula J. Rudal

Characterization of Linaria KNOX genes suggests a role in petal-spur development

Spurs are tubular outgrowths of perianth organs that have evolved iteratively among angiosperms. They typically contain nectar and often strongly influence pollinator specificity, potentially mediating reproductive isolation. The identification of Antirrhinum majus mutants with ectopic petal spurs suggested that petal-spur development is dependent on the expression of KNOTTED 1-like homeobox (KNOX) genes, which are better known for their role in maintaining the shoot apical meristem. Here, we tested the role of KNOX genes in petal-spur development by isolating orthologs of the A. majus KNOX genes Hirzina (AmHirz) and Invaginata (AmIna) from Linaria vulgaris, a related species that differs from A. majus in possessing long, narrow petal spurs. We name these genes LvHirz and LvIna, respectively. Using quantitative reverse-transcription PCR, we show that LvHirz is expressed at high levels in the developing petals and demonstrate that the expression of petal-associated KNOX genes is sufficient to induce sac-like outgrowths on petals in a heterologous host. We propose a model in which KNOX gene expression during early petal-spur development promotes and maintains further morphogenetic potential of the petal, as previously described for KNOX gene function in compound leaf development. These data indicate that petal spurs could have evolved by changes in regulatory gene expression that cause rapid and potentially saltational phenotypic modifications. Given the morphological similarity of spur ontogeny in distantly related taxa, changes in KNOX gene expression patterns could be a shared feature of spur development in angiosperms. Mathew S. Box, Steven Dodsworth, Paula J. Rudall, Richard M. Bateman, Beverley J. Glove

Phylogenomics and evolution of floral traits in the Neotropical tribe Malmeeae (Annonaceae)

Androdioecy is the rarest sexual system among plants. The majority of androdioecious species are herbaceous plants that have evolved from dioecious ancestors. Nevertheless, some woody and androdioecious plants have hermaphrodite ancestors, as in the Annonaceae, where androdioecious genera have arisen several times in different lineages. The majority of androdioecious species of Annonaceae belong to the Neotropical tribe Malmeeae. In addition to these species, Pseudoxandra spiritus-sancti was recently confirmed to be androdioecious. Here, we describe the morphology of male and bisexual flowers of Pseudoxandra spiritus-sancti, and investigate the evolution of androdioecy in Malmeeae. The phylogeny of tribe Malmeeae was reconstructed using Bayesian inference, maximum parsimony and maximum likelihood of 32 taxa, using DNA sequences of 66 molecular markers of the chloroplast genome, sequenced by next generation sequencing. The reconstruction of ancestral states was performed for characters associated with sexual systems and floral morphology. The phylogenetic analyses reconstructed three main groups in Malmeeae, (Malmea (Cremastosperma, Pseudoxandra)) sister to the rest of the tribe, and (Unonopsis (Bocageopsis, Onychopetalum)) sister to (Mosannona, Ephedranthus, Klarobelia, Oxandra, Pseudephedranthus fragrans, Pseudomalmea, Ruizodendron ovale). Hermaphroditism is plesiomorphic in the tribe, with four independent evolutions of androdieocy, which represents a synapomorphy of two groups, one that includes three genera and 14 species, the other with a single genus of seven species. Male flowers are unisexual from inception and bisexual flowers possess staminodes and functional stamens. Pseudoxandra spiritus-sancti is structurally androdioecious

Embryo and seedling morphology in Trithuria lanterna (Hydatellaceae, Nymphaeales): new data for infrafamilial systematics and a novel type of syncotyly

Keywords: anatomy; cotyledon; embryology; evolution; gravitropism; heterocotyly; monocots; seed germination; vasculature The monogeneric early-divergent angiosperm family Hydatellaceae (Trithuria) was formerly placed in the monocots and shows several features that are at least superficially monocot-like. Seedlings of Hydatellaceae are unusually diverse and have been interpreted as either dicotylar or monocotylar. We provide the first detailed developmental description of seedlings of Trithuria lanterna (including the first data on mature embryos of tropical Hydatellaceae) as a basis for the general discussion of seedling diversity in Hydatellaceae. Seedlings at various stages after germination were studied using serial sections and scanning electron microscopy. The embryo is dicotylar. It lacks pronounced asymmetry and lacks a plumule before seed germination. In the majority of seedlings, the cotyledons are free and appear attached to the seedling axis at different levels. In other seedlings, the cotyledons are united via a non-haustorial leaf-like organ; this alternative condition represents a novel type of syncotyly for seed plants and a second type of syncotyly recorded for Hydatellaceae. Seedling morphology is determined by strong one-sided growth of the hypocotyl, which is an unusual way of overcoming the basic seed plant spatial constraint at germination. The direction of one-sided growth is independent of cotyledon orientation and could be environmentally determined. Seedlings provide synapomorphies for the two major clades of Trithuria, which can be regarded as subgenera. Although no direct homology is inferred, the exceptional degree of morphological variation in Hydatellaceae seedlings, including the variable occurrence of several superficially monocot-like features, leads us to hypothesize that the stem group of monocots could have exhibited an analogous degree of variation in cotyledon morphology. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 201