Monthly Archives: October 2011

Chromosome pairing in Musa interspecific cultivars

Chromosome pairing in Musa interspecific cultivars

Chromosome pairing in Musa interspecific cultivars

Most cooking and several desert bananas are interspecific triploid hybrids between Musa acuminata (A genome) and M. balbisiana (B genome). To investigate the possibility of chromosome exchanges between these two species, Jeridi et al. develop a genomic in situ hybridization protocol suitable for analysing meiosis metaphase I from Musa pollen mother cells. They demonstrate that chromosome pairing between M. acuminata and M. balbisiana chromosomes is frequent in triploid interspecific hybrids, results that both provide new insight into cultivar evolution and have important implications for future breeding.

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Reticulate evolution and triploidy in Diphasiastrum

Reticulate evolution and triploidy in Diphasiastrum

Reticulate evolution and triploidy in Diphasiastrum

Diphasiastrum species have been assumed to produce homoploid hybrids whose reproductive competence is still a matter of debate. Using flow cytometry, Bennert et al. demonstrate that the three Central European primary hybrids are consistently homoploid. Their nuclear DNA amounts are invariable and intermediate between the parents; no indications for diploid backcrossing are found. Higher DNA amounts occur in three presumably triploid populations, which arose by a secondary hybridization event, probably involving unreduced diplospores formed by a diploid hybrid.

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Characterization of 3-D patterns of disease in cherry

Characterization of 3-D patterns of disease in cherry

Characterization of 3-D patterns of disease in cherry

Spatial patterns of plant disease provide important information about pathogen source, spread and reproduction. Using point pattern analysis, Everhart et al. generate detailed three-dimensional maps of different symptom types of brown rot (Monilinia laxa) in sour cherry tree (Prunus cerasus) canopies to characterize symptom aggregation and association. This mapping and analysis framework, which quantitatively supports the importance of twig cankers as an inoculum source within individual trees, should be applicable to many fields of canopy research.

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Molecular control of legume nodulation (Botanical Briefing)

Molecular control of legume nodulation

Molecular control of legume nodulation

Legume plants enter into symbiotic relationships with soil bacteria in order to obtain nitrogen to sustain plant growth. The nodulation associated with this is regulated in response to both internal developmental signals via the autoregulation of nodulation (AON) and by environmental signals, such as the availability of soil nitrogen. Reid et al. focus on the conservation of key components between AON and the regulation of other plant developmental processes and argue that these similarities will benefit progress in understanding both nodulation and plant development.

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Botany for Halloween – Witches, Brooms and Pumpkins

A witch with broom, pumpkins and orange clothes

A witch with broom, pumpkins and orange clothes

At the moment, I am teaching plant hormones in our course on plant cell and developmental biology (BS1003). Fortunately, hormones and development link well with Halloween this year: we have witches, sitting on a broom, with a pumpkin, and for good measure some brightly colored leaves falling around them. Where is the connection?

The broom is a good point to start : many species of trees have “witch’s brooms” on them, structures where a large number of small twigs arise from one region of a branch or the main trunk. The uncontrolled outgrowths are caused by other organisms which either make their own phytohormones which induce the host plant to produce the multiple branches, or by the other organisms altering the plant’s own regulation of hormones.

A Witch's Broom on a tree trunk

A Witch's Broom on a tree trunk

Insects (including wasps or mites), fungi, viruses or even hemiparasitic plants like mistletoe cause the upset in the balance between the major hormones including auxins and cytokinins so the plant generates new meristems within the stem or trunk which grow out as shoots.

What about the witch herself? The state of being a witch is partly a behavioural anomaly and partly physical, and many of the symptoms including hallucinations, seizures and skin effects are those from ergot poisoning or Saint Anthony’s Fire. Although the symptoms “are not actually caused by bewitchment”, Wikipedia discusses the Medical Explanations of Bewitchment, and ergot poisoning is one widely suggested cause, particularly among the infamous Salem Witches of Massachusetts in the 17th century. The fungus Claviceps purpurea infects the ears of rye plants, and the fungal fruiting body (sclerotium) replaces the seed. This parasitic lifestyle involves taking nutrients from the plant (as though they were going to a seed), and the sclerotium then also takes advantage

Ergot In Rye Ear

Ergot In Rye Ear

of the dispersal mechanism and it is carried around along with the seeds. When the rye is milled for bread, the sclerotium is included and the alkaloids including psychedelic drug relatives and toxins in the ergoline family are eaten, possibly giving rise to witch-like behaviour.

The link of plant hormones and plant development to the pumpkins is slightly more stretched – through sex determination. The first flowers of the ground-spreading vines of many cucurbits are male, and later ones are female or a mixture of male and female. Hormones are responsible for the changing sex of the flowers, but interestingly, one hormone can have a opposite effects in different plants: gibberellin application will change cucurbit flowers to males, while making maize flowers female.

Now, for chromosome biology, all I need is a witch with a tortoiseshell or calico cat, rather than their favoured black cats, so that I can discuss inactivation of the genes on the X chromosome leading to the coat variegation!

 

 

Addition 1 Nov: The comments give a number of interesting links to other stories about egotism. The Scientist Gardener has an impressive post on Claviceps / Ergot from the end of 2010.

A Calico Cat showing X Inactivation in the organge and black areas - not the type favoured by witches

A Calico Cat showing X Inactivation in the orange and black areas - not the type favoured by witches

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Free—open access paper: Evolutionary development of the plant spore and pollen wall

This article provides an overview of the development and structure of spore and pollen walls in the major plant groups and summarises progress in our understanding of the molecular genetics underpinning spore/pollen evolution and development.

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Facing the music

US Bureau of American Ethnology, 1916.

US Bureau of American Ethnology, 1916.

Plants are daily subjected to myriad biotic and abiotic factors and have to respond appropriately to them or suffer the consequences. However, one factor they’ve probably not been subjected to for much of their evolutionary history is… music. Whether music should be considered abiotic or biotic is a moot point, but an investigation into how vegetation responds to the ‘sound of the harmonic spectrum’ was undertaken when the UK’s Royal Philharmonic Orchestra played for an audience – presumably invited – of ‘100 different varieties of plants and bulbs including geraniums, fuschias [sic] and perennials’. Organised by shopping channel QVC the aim was to test the notion that the reverberation of sound waves stimulates protein production in plants and may lead to increased growth. Months on, I’ve not managed to track down the results of this important experiment; can anybody help me? If you’re keen to try the experiment for yourself (or turn it into a student-led project??), a 45-minute album based on the performance, ‘The Floral Seasons: Music to Grow To’, is available to download. [I’d like to make it clear that I have no financial interest in the QVC Channel. In fact I hadn’t heard of it until researching this news item!] This story has some resonance (pun intended…) with an older report that suggests that talking to tomato plants leads them to grow taller. And the voice that seemed to have the greatest response in this regard – and you really couldn’t make it up! – belonged to Sarah Darwin (yep, great-great-granddaughter of the Galapagos gazetteer himself, good old Charles…), who appropriately enough was studying Galapagos Solanum at the time. For more on this fascinating topic, do look at the ‘Probing Question: Does talking to plants help them grow?’ at http://www.physorg.com/news139763645.html.

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Open Access Plant Science – Every Week of the Year

Climate This week is Open Acess Week, the annual event celebrating the global movement towards Open Access (OA) to research and scholarship.

Here at AoB Blog we try to do our bit to make current research in plant science accessible and interesting to a wide audience, but the Annals of Botany Company goes way beyond that in publishing AoB PLANTS, an online internationally peer reviewed open-access journal publishing high quality papers on all aspects of plant biology – that are free for anyone to read, anywhere in the world. It costs a surprising amount of money to produce a high quality research journal, but Annals of Botany keeps publication charges lower than most similar journals, and we maintain our other reader- and author-friendly policies for all our contributors, including no page charges for authors, authors retaining copyright on all their work, free access to many review articles, increasing amounts of editorial material including ContentSnapshots, Plant Cuttings, and book reviews, wide free distribution of Special Issues of the journal.

So why does any of this matter? Because although developing countries, where the twin threats of climate change and food security are likely to have the greatest adverse effects, spend a disproportionately high amount of money on plant science research, funding is still severely limited. And without access to the best and most recent discoveries in plant science, the future for developing countries looks bleak.

You can afford to worry about medical research once you have enough food to eat.

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Latin is dead (Official!)

Chris McKenna/Wikimedia Commons.

Chris McKenna/Wikimedia Commons.

It’s been a feature of botany that ever since the language of Ancient Rome became the lingua franca of the educated classes, descriptions of new plants were published in Latin. Sadly, new rules emanating from the august XVIII International Botanical Congress (held in Melbourne, Australia, in July 2011) will put paid to that tradition. The changes are described by James Miller et al. (sorry, ‘and others’…) in their informatively entitled paper ‘Outcomes of the 2011 Botanical Nomenclature Section at the XVIII International Botanical Congress’ (Phytokeys 5: 1–3, 2011). To summarise, the Code [the ICBN – International Code of Botanical Nomenclature – that deals with the naming of plants, fungi and photoautotrophic protists (‘algae’)] is amended to the International Code of Nomenclature of algae, fungi, and plants (the ICN); names of new taxa can be published electronically [!! – Ed.]; and descriptions (‘the validating diagnoses’) of new taxa can either be in Latin or in English [I do hope that’s English (UK)! – Ed.]. The latter two changes will take effect on 1st January 2012 (no, not 1st April – I checked this specifically!). If that news still leaves you concerned that you might not spell plant names – which are still Latinised – correctly, then you may want to use the services of the TNRS (Taxonomic Names Resolution Service), ‘a free utility for correcting and standardizing plant names’. Read more about that at http://www.nature.com/news/2011/110613/full/474263a.html. One shouldn’t be too surprised with the move from Latin to English; after all, English is the language of international science. It just comes as a bit of a shock after all those centuries… Still, one must move with the times (a bit like accepting screw-tops on antipodean wine bottles, I guess…).

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Ontogeny and responses to apical damage

Ontogeny and responses to apical damage

Ontogeny and responses to apical damage

Plants can tolerate tissue loss through vigorous branching, often triggered by release from apical dominance and activation of lateral meristems. In the annual plant Medicago truncatula, Gruntman and Novoplansky show that damage-induced meristem activation is an adaptive response that can be modified according to the plant’s developmental stage, severity of tissue loss and their interaction. Plants exhibit an ontogenetic shift in tolerance mechanisms: while early apical damage induces activation of vegetation meristems, late damage elicits increased allocation to already existing reproductive organs.

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