Leitch A.R.,Queen Mary, University of London |
Leitch I.J.,Jodrell Laboratory
New Phytologist | Year: 2012
The large-scale replacement of gymnosperms by angiosperms in many ecological niches over time and the huge disparity in species numbers have led scientists to explore factors (e.g. polyploidy, developmental systems, floral evolution) that may have contributed to the astonishing rise of angiosperm diversity. Here, we explore genomic and ecological factors influencing seed plant genomes. This is timely given the recent surge in genomic data. We compare and contrast the genomic structure and evolution of angiosperms and gymnosperms and find that angiosperm genomes are more dynamic and diverse, particularly amongst the herbaceous species. Gymnosperms typically have reduced frequencies of a number of processes (e.g. polyploidy) that have shaped the genomes of other vascular plants and have alternative mechanisms to suppress genome dynamism (e.g. epigenetics and activity of transposable elements). Furthermore, the presence of several characters in angiosperms (e.g. herbaceous habit, short minimum generation time) has enabled them to exploit new niches and to be viable with small population sizes, where the power of genetic drift can outweigh that of selection. Together these processes have led to increased rates of genetic divergence and faster fixation times of variation in many angiosperms compared with gymnosperms. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.
Rudall P.J.,Jodrell Laboratory
Current Opinion in Plant Biology | Year: 2010
Understanding floral patterning is a primary goal in plant biology, yet the temporal sequence of organ development is rarely factored into developmental models. In flowers, occasional examples of centrifugal or basipetal organ initiation, both within organ zones (intrazonal) and between them (interzonal), present a paradox with respect to developmental models. A centripetal/acropetal sequence of floral organ initiation is ancestral in angiosperms, but centrifugal/basipetal development has evolved many times, indicating that these apparently major developmental shifts have relatively simple genetic triggers. Review of the sequence of organ initiation in angiosperms supports evidence that the four floral organ types develop independently of each other, in response to genetic factors that predetermine radial patterning. © 2009 Elsevier Ltd. All rights reserved.
Veitch N.C.,Jodrell Laboratory
Natural Product Reports | Year: 2013
This account describes 275 new isoflavonoids published between 2008 and 2011 as constituents of the Leguminosae, commenting on their source, identification, biological activity, synthesis, and ecological or chemosystematic significance. Applications of hyphenated analytical techniques to the characterisation of Leguminosae isoflavonoids are also reviewed, together with advances in biosynthetic studies. A checklist of new compounds by species is given, and 226 references are cited. This journal is © The Royal Society of Chemistry.
Prenner G.,Jodrell Laboratory
Annals of Botany | Year: 2013
Background and Aims The inflorescence structure determines the spatiotemporal arrangement of the flowers during anthesis and is therefore vital for reproductive success. The Leguminosae are among the largest angiosperm plant families and they include some important crop plants. In papilionoid legumes, the raceme is the most common type of inflorescence. However, a range of other inflorescence types have evolved via various developmental processes. A (re-)investigation of inflorescences in Swainsona formosa, Cicer arietinum, Abrus precatorius, Hardenbergia violacea and Kennedia nigricans leads to new insights into reduction mechanisms and to a new hypothesis on the evolution of the papilionoid pseudoraceme. Methods Inflorescence morphology and ontogeny were studied using scanning electron microscopy (SEM). Key Results The inflorescence in S. formosa is an umbel with a rare type of pendulum symmetry which may be triggered by the subtending leaf. Inflorescences in C. arietinum are reduced to a single flower. An early formed adaxial bulge is the sterile apex of the inflorescence (i.e. the inflorescence is open and not terminated by a flower). In partial inflorescences of A. precatorius, the axis is reduced and its meristem is relocated towards the main inflorescence. Flower initiation follows a peculiar pendulum pattern. Partial inflorescences in H. violacea and in K. nigricans show reduction tendencies. In both taxa, initiated but early reduced bracteoles are present. Conclusions Pendulum symmetry in S. formosa is probably associated with distichous phyllotaxis. In C. arietinum, strong reduction tendencies are revealed. Based on studies of A. precatorius, the papilionoid pseudoraceme is reinterpreted as a compound raceme with condensed lateral axes. From an Abrus-like inflorescence, other types can be derived via reduction of flower number and synchronization of flower development. A plea is made for uniform usage of inflorescence terminology.©The Author 2013. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved.
Green P.W.C.,Jodrell Laboratory
Journal of Stored Products Research | Year: 2011
A methanol fraction (MFr), prepared from 80% methanol extracts of whole Liposcelis bostrychophila, repels conspecifics when presented to groups of insects at 8000 ppm. To examine the reason for this repellent effect, bioassays tested a mixture of fatty acids and fatty acid methyl esters that are present in the MFr at concentrations ranging from 0.02 to 1.2 mM. This mixture of compounds contributes significantly to the repellence of the MFr. Therefore, an interaction among compounds can affect the settling behaviour of L. bostrychophila, even though the individual compounds do not have any effect. Other experiments further investigated the repellence of C16 and C18 fatty acids. In the majority of instances groups of insects consistently settled on the disc impregnated with either stearic acid or the compound with the most saturated bonds. The one exception was C18:2 versus C18:3 where more insects settled on C18:3. This repellent effect of unsaturated fatty acids was also evident in five-way choice tests using a series of C18 fatty acids, where stearic acid (10 mM) was consistently selected by groups of L. bostrychophila instead of oleic, linoleic and linolenic acid. The discrimination between and among fatty acids could be due to the differences in their physical properties which affect how the compounds are perceived by the insects. The fact that the most unsaturated fatty acids repel the insects presents the possibility that volatile insect-derived compounds could be utilised as repellents for this increasingly important pest. © 2011 Elsevier Ltd.