Jean M. Gerrath

Transcriptome Sequences Resolve Deep Relationships of the Grape Family

Previous phylogenetic studies of the grape family (Vitaceae) yielded poorly resolved deep relationships, thus impeding our understanding of the evolution of the family. Next-generation sequencing now offers access to protein coding sequences very easily, quickly and cost-effectively. To improve upon earlier work, we extracted 417 orthologous single-copy nuclear genes from the transcriptomes of 15 species of the Vitaceae, covering its phylogenetic diversity. The resulting transcriptome phylogeny provides robust support for the deep relationships, showing the phylogenetic utility of transcriptome data for plants over a time scale at least since the mid-Cretaceous. The pros and cons of transcriptome data for phylogenetic inference in plants are also evaluated.

Primary Vascular Patterns in the Vitaceae

Vitaceous shoots can be classified into five distinct architectural patterns based on a three‐node sequence of tendril and axillary bud presence. The relationship between two of the more commonly occurring patterns and their primary vasculature was examined. Cissus alata was chosen to represent pattern 5 (distichous phyllotaxy and continuous leaf‐opposed tendril/inflorescences) and Vitis riparia to represent pattern 4 (distichous phyllotaxy and a three‐node modular pattern of interrupted leaf‐opposed tendril/inflorescences). Both species show architectural dorsiventrality in that the prophyll of the first‐order axillary bud is ventral and vascular dorsiventrality in that all midvein leaf traces arise from ventral vascular sympodia. Both taxa have an even number of vascular sympodia, with four in C. alata and six in V. riparia. Leaf traces are multilacunar, with seven traces in C. alata and five in V. riparia. The leaf‐opposed tendril/inflorescences have the same vascular architecture as the axillary buds and are derived from the same vascular sympodia, although there is no evidence from this study that the tendrils represent a vertically displaced serial axillary bud. Vascular architecture reflects the underlying three‐node modularity of these shoot patterns in two ways: first, leaf traces in both species most commonly arise three nodes below their point of departure from the stem, and second, the number of internodes the axillary bud traces traverse is dependent on the position of the tendril within the shoot module in V. riparia (pattern 4). Vegetative characters such as shoot architecture and primary vascular pattern should prove useful in phylogenetic analyses of this architecturally unique family.

Shoot architecture in the VitaceaeThis article is one of a selection of papers presented at the symposium on Vitis at the XVII International Botanical Congress held in Vienna, Austria, in 2005.

This paper examines the question of how the unique shoot architectural pattern of the Vitaceae, typically with leaf-opposed tendrils or inflorescences in a three-node modular repetitive pattern, can be related to the traditional concepts of monopodial and sympodial shoot development. Based on complete comparative morphological developmental studies of 13 species in six genera, supplemented with observations of 21 other taxa, we have found five shoot architectural patterns in the family. The pattern of shoot architecture is consistent within a species, but there may be more than one pattern present within a genus. Species that lack tendrils, thus exhibiting pattern 1, show sympodial growth. Taxa exhibiting patterns 2, 3, and 4, with tendrils at two of three nodes and with progressively one, two, or three axillary buds within the three-node cycle, grow monopodially, and taxa that exhibit pattern 5, with both tendrils and axillary buds at every node, achieve the pattern via either monopodial or sympodial gro...

Developmental and morphological analyses of homeotic cytoplasmic male sterile and fertile carrot flowers

Floral development and morphology were observed for two homeotic cytoplasmic male sterile carrot lines and their isonuclear fertile maintainers. For one sterile line, W33A stamens are replaced by petal-like organs; for the other, W259A, both stamens and petals are replaced by green bract-like structures. Both isonuclear maintainers, W33B and W259B respectively, have stamens and white petals. The different sterile phenotypes result from the interactions of distinct nuclear genotypes with one sterility-inducing cytoplasm. Early stages of floral development were similar among all four lines; the third whorl primordia were radial while those in the second whorl were dorsiventral. However, the third whorl primordia were splayed outward in the sterile lines and inward in the fertile lines. Subsequently, radial anthers on filaments differentiated in fertile lines and dorsiventral hastate and cordate shaped structures appeared in W33A and W259A, respectively. In the mature flower, the third whorl organs were cordate in W33A and ovate in W259A. Based on epidermal cell morphology, the second whorl organs of the two sterile lines had characteristics of both petals and bracts, but of opposite degrees; cells of W33A and W259A were most similar to those of petals and bracts, respectively. The third whorl organs of the sterile lines had characteristics of their respective second whorl organs; however, structures of W33A also had filament-like cells and those of W259A were more bract-like than their respective second whorl organs. The cytoplasm affected when homeosis was manifested during development. Nuclear factors interacting with cytoplasm were most important for determining differentiation. The significance of cytoplasm to current models of nuclear-gene-controlled homeosis is discussed.

The Developmental Morphology of Leea guineensis. II. Floral Development

The floral development of Leea guineensis G. Don is described, using three-dimensional and histological observations. Inflorescences may be terminal or axillary. Axillary inflorescences, however, arise only in the axil of the uppermost leaf on the shoot in conjunction with a terminal inflorescence. Inflorescence branches are initiated spirally and are preceded by the formation of subtending bracts. Subsequent orders of branches arise as pairs of primordia, each at 90⚬ from the previous pair. The ultimate inflorescence pattern is a compound dichasium. Flowers are pentamerous. Sepals arise spirally. Petals arise simultaneously, alternate with the sepals, and are cucullate, valvate, and reflexed at anthesis. Stamens are petal-opposed. The anthers are connivent and hook over the floral disc prior to anthesis. At anthesis the anthers are reflexed and may appear extrorse. Pollen is tricolporate. The gynoecium arises as a ring primordium, from which three units are formed as the result of inward growth of three primary septa from the gynoecial wall. Two ovules form at the base of the septum of each unit, and subsequently three secondary septa form, effectively forming six locules at maturity. Ovules are bitegmic, anatropous, and crassinucellate. The ovary is half-inferior at maturity. Flowers are markedly protandrous. Fruits were not formed in the material observed.

Development of the axillary bud complex in Echinocystis lobata (Cucurbitaceae): interpreting the cucurbitaceous tendril

In the Cucurbitaceae, the tendrils, coiling organs used for climbing and mechanical support, are part of an axillary bud complex (ABC). Although the morphological nature of tendrils and the branching pattern of the ABC in the Cucurbitaceae have been much studied, their homology remains unresolved, with hypothesized candidates being the leaf, flower, stem, or stem-leaf combination. We used Echinocystis lobata as a model to study the early ontogeny of the ABC with epi-illumination microscopy and serial resin sections. The ABC produces four structures (proximal to distal, relative to the subtending leaf) as the result of two successive subdivisions: an inflorescence of staminate flowers, a solitary pistillate flower, a lateral bud, and a tendril. The first separates the tendril primordium from the continuation of the ABC, and the second separates the staminate inflorescence and the ABC. The pistillate flower apparently forms between the staminate inflorescence and the lateral bud. Because there is no subtending leaf during these subdivisions and the first lateral appendages in the resulting primordia arise in the same plane, we conclude that the tendril and other organs formed by the ABC are lateral branches of equal morphological value. This study is the basis for continuing comparative and functional morphological studies.

Inflorescence morphology and development in the basal rosid lineage Vitales

This review summarizes inflorescence developmental morphology in the grape order Vitales within a phylogenetic context. Inflorescences in the shrubby Leeaceae are terminal thyrses that appear leaf‐opposed once renewal growth begins. Plants of the Vitaceae are mainly tendrilled lianas and form five well‐defined clades. Inflorescences develop from the unique, non‐leafy, uncommitted primordium which arises opposite a leaf on the flank of the shoot apical meristem, and may mature into an inflorescence, tendril, or a combination of the two. The Ampelopsis‐Rhoicissus clade, Cissus antarctica group and Yua have a tendril/inflorescence, with cymose branching on the inflorescence axis. Inflorescences in the core Cissus clade and Cyphostemma‐Tetrastigma clade arise on a compressed axillary shoot, and leaf‐opposed tendrils arise on the main shoot, resulting in different branch orders. In Parthenocissus, tendrils are leaf‐opposed on long shoots, and inflorescences are leaf‐opposed on axillary branches on short shoots. In the Ampelocissus‐Vitis clade, the leaf‐opposed tendrils and thyrse inflorescences are of the same branching order, and are often combined. Terminal inflorescences such as in Leeaceae are common in angiosperms, in contrast to the unique leaf‐opposed tendril/inflorescence of Vitaceae. The further separation of the tendrils and inflorescences onto different orders of branching (core Cissus, Cyphostemma‐Tetrastigma), or separate short and long shoots (Parthenocissus), have allowed each component to optimize its own function. The Ampelocissus‐Vitis clade, however, has returned to a thyrse inflorescence, which may allow for larger or unusual lamellate inflorescences (Pterisanthes), and has reunited tendrils and inflorescences. Thus, each clade has developed its own set of inflorescence morphology.

A new phylogenetic tribal classification of the grape family (Vitaceae): Tribal classification of Vitaceae

Vitaceae (the grape family) consist of 16 genera and ca. 950 species primarily distributed in tropical regions. The family is well‐known for the economic importance of grapes, and is also ecologically significant with many species as dominant climbers in tropical and temperate forests. Recent phylogenetic and phylogenomic analyses of sequence data from all three genomes have supported five major clades within Vitaceae: (i) the clade of Ampelopsis, Nekemias, Rhoicissus, and Clematicissus; (ii) the Cissus clade; (iii) the clade of Cayratia, Causonis, Cyphostemma, Pseudocayratia, Tetrastigma, and an undescribed genus “Afrocayratia”; (iv) the clade of Parthenocissus and Yua; and (v) the grape genus Vitis and its close tropical relatives Ampelocissus, Pterisanthes and Nothocissus, with Nothocissus and Pterisanthes nested within Ampelocissus. Based on the phylogenetic and morphological (mostly inflorescence, floral and seed characters) evidence, the new classification places the 950 species and 16 genera into five tribes: (i) tribe Ampelopsideae J.Wen & Z.L.Nie, trib. nov. (47 species in four genera; Ampelopsis, Nekemias, Rhoicissus and Clematicissus); (ii) tribe Cisseae Rchb. (300 species in one genus; Cissus); (iii) tribe Cayratieae J.Wen & L.M.Lu, trib. nov. (370 species in seven genera; Cayratia, Causonis, “Afrocayratia”, Pseudocayratia, Acareosperma, Cyphostemma and Tetrastigma); (iv) tribe Parthenocisseae J.Wen & Z.D.Chen, trib. nov. (ca. 16 spp. in two genera; Parthenocissus and Yua); and (v) tribe Viteae Dumort. (ca. 190 species in two genera; Ampelocissus and Vitis).

Gynoecial Structure of Vitales and Implications for the Evolution of Placentation in the Rosids

Premise of research. Evolutionary relationships of the Vitales (the economically important Vitaceae and its sister family Leeaceae) within the rosids have been difficult to resolve. Gynoecial structure, especially the placentation type, of the two families has been variously interpreted. A survey of gynoecial structure is undertaken within these two families, and they are interpreted in light of phylogenetic comparison of placentation types among all angiosperms. Methodology. Gynoecial structure and architecture in 21 species were studied with light and scanning electron microscopy. Ancestral character reconstruction of gynoecia with axile, parietal, basal, apical, free-central, marginal, or laminar placentae across 640 taxa representing all 58 orders of angiosperms was inferred using maximum likelihood to help interpret the evolution of the gynoecium in the Vitales. Pivotal results. The syncarpous ovary is bicarpellate in Vitaceae and tricarpellate in Leeaceae; in both the carpels are congenitally fused to form the synascidiate zone. Placentae are located basally on the septum with generally two ovules per carpel. Distally, septa are incomplete, resulting in the ovary being incompletely bilocular in Vitaceae and incompletely trilocular in Leeaceae. Further morphological variations are a result of differential growth of the septa. In some species of Cyphostemma septa are further reduced, and the ovary is clearly unilocular. Ancestral character reconstruction using maximum likelihood across 640 angiosperm taxa infers marginal placentation to be the ancestral condition, while that of the Superrosidae is axile, with basal placentation inferred to be derived within the clade. Conclusions. The apically incompletely septate gynoecia and basally septate gynoecia of Vitaceae and Leeaceae are also found in 31 other angiosperm families. These results underscore the labile nature of placentation despite its long use as a character of taxonomic significance. The study provides a basis for inferring the directionality of placentation evolution in the context of a wider investigation of rosid relationships.

The Developmental Morphology of Leea guineensis. I. Vegetative Development

The early ontogeny of the compound leaves and their associated stipules in Leea guineensis G. Don was studied using SEM. At initiation, the leaf primordium uses up most of the shoot apical meristem, which fluctuates greatly in size at different stages of development. Continuous meristematic regions at the base of the leaf primordium, later recognized as stipules, grow around and enclose the apical meristem. The continuity between the leaf, the stipules, and the shoot axis is striking at early stages of development, making it difficult to delimit these different structures. If growth processes such as timing and duration of growth and meristem fusion or extension are used to explain the vegetative morphology of L. guineensis, visualizing the relationship between the leaf, the stipules, and the shoot axis becomes easier.