Tag Archives: Angiosperm

Inflorescences take centre stage

Inflorescences issue cover Annals of Botany has a new special issue in Free Access: Inflorescences. It’s a useful reminder to me of another area of Botany I need to read more about.

For a start, I think I’ve said elsewhere that inflorescences are the structures where there are multiple flowers on a plant and not just a single flower. In a clumsy way this might be true but it also misses the point of an inflorescence. It’s not simply that there are multiple flowers, but also that those flowers work with each other as unit. They’re not just a collection of individuals.

If you approach inflorescences from this point of view, their structure becomes a bit of a puzzle. Why the diversity? But also, can you classify them sensibly and, if you can, what is the basis of that? Do different structures correspond with different functions?

Lawrence Harder and Przemyslaw Prusinkiewicz describe the interplay between inflorescence development and function as the crucible of architectural diversity. It highlights the importance of linking structures and function. In terms of tracing plant relationships, structure is useful but it’s also worth looking at what the structure does. A similar structure could have a very different result if the phenology, the timing of the flowering, changes.

Time is key factor that is highlighted by Harder and Prusinkiewicz. Looking at a display, it’s easy to think of it as an organisation in space, but they also make a point that inflorescences are dynamic. They change with time, and how they change with time has consequences for their function.

As far as plant reproduction goes, it’s easy to focus on the success of flowers, but Harder and Prusinkiewicz argue that what you have is part of a modular system, and that to understand it you have to look at the system as a whole, instead of modules in isolation. Most angiosperms use inflorescences so it’s clearly a powerful tool for a plant. Looking at them as a unit and not just parts can put plant reproduction into a new context.

Harder L.D. & Prusinkiewicz P. (2012). The interplay between inflorescence development and function as the crucible of architectural diversity, Annals of Botany, 112 (8) 1477-1493. DOI: http://dx.doi.org/10.1093/aob/mcs252

Phylogeny of OVATE family proteins in land plants

Phylogeny of OVATE family proteins in land plants

Phylogeny of OVATE family proteins in land plants

The OVATE gene encodes a nuclear-localized regulatory protein belonging to a distinct family of plant-specific proteins known as the OVATE family proteins (OFPs). Liu et al. identify 13 sequenced plant genomes in public databases that represent the major evolutionary lineages of land plants and conduct a phylogenetic analysis based on the alignment of the conserved OVATE domain. Genes for OFPs are found to be present in all the sampled land plant genomes, including the early-diverged lineages, mosses and lycophytes, and 11 subgroups of OFPs are defined in angiosperms. The results provide new insights into the evolution of the OVATE protein family and establish a solid base for future functional genomics studies on this important but poorly characterized regulatory protein family.

 

Floral specialization and angiosperm diversity: Phenotypic divergence, fitness trade-offs, and realized pollination accuracy

13092R1Plant reproduction by means of flowers has long been thought to promote the success and diversification of angiosperms. It remains unclear, however, how this success has been come about. A recent review by Scott Armbruster published in AoB PLANTS considers the role of reproductive factors in the evolutionary success of flowering plants, with emphasis on flowers and pollination. Flowers are complex structures that have varying degrees of integration of parts and surprising evolutionary lability. Diversification of floral form usually accompanies plant diversification by speciation. This correlation has traditionally been interpreted as the result of floral specialization increasing speciation rates. However, another possibility is that species diversity generates selection for divergent specialized flowers when related species occur together, thereby reducing extinction rates.

Cabomba as a model basal angiosperm (Review)

Cabomba as a model basal angiosperm (Review)

Cabomba as a model basal angiosperm (Review)

Early-diverging angiosperms are important for studies of the origin and early evolution of the flower. Vialette-Guiraud et al. discuss the potential of the water lily Cabomba (Nymphaeales) as a model basal angiosperm, as it combines simplicity of floral structure, numerous pleisiomorphic angiosperm characters, and practical features that make it amenable to study using a broad range of molecular biological techniques. They also provide protocols for the growth and molecular analysis of Cabomba, a Cabomba flower EST database, and a genome size measurement of C. caroliniana.

Growth regulators and germination of recalcitrant seeds

Growth regulators and germination of recalcitrant seeds
Growth regulators and germination of recalcitrant seeds

There is relatively little information avialable regarding the role of plant growth regulators in the germination of recalcitrant seeds. Pieruzzi et al. determine an increase in the ratio of the polyamines (spermidine + spermine) : putrescine in the embryos of germinating Araucaria angustifolia (gymnosperm) and Ocotea odorifera (angiosperm), which could be used as a marker for germination completion. An unexpected increase of ABA levels was observed in A. angustifolia embryos, which suggests a potential role for this rgeulator in some recalcitrant seeds.