Friday 23 August 2013

Bean there

At last Jack's beans in the polytunnel are starting the bear 'fruit'.  I call them Jack's because they are very tall and commendably bean-stalky.  This is the second round of propagation of some tall beans that I saved from the late-lamented poly-tunnel of "Rissoles" Hayes from Wexford.  That structure frapped itself to ribbons in a couple of storms and they took down the skeleton last year to move it somewhere more sheltered.  Our tunnel is 4.5m high in the centre and these beans grow up that high and then start entangling themselves so it looks a bit like rural Brazil up there.  

ANNyway, the interesting thing about picking haricot beans, apart from the fact that they have white, yellow, pink and purple flowers, is how hard it can be.  It's as if the bean was trying to avoid predation.  It's not so much that the beans grow under dinner-plate-sized leaves, although they do, but that other parts of the plant look disconcertingly like the bean-pods.  The leaves have a wee point opposite the stalk and so do the bean-pods and the stalks are the same diameter and colour as the pods, so I keep reaching for a mouthful of dinner and coming up empty.  What's all that about?  It must be that the growth and development of the whole plant is under the control of a limited number of genes and whatever mutations are present they affect all the devt systems in similar ways.

We sort of know this from looking at the development of plants like magnolia where it is much less clear that the flesh appendage you're looking at is a leaf, a sepal or a petal.  Now that they have sequenced the complete genome of a number of plants, we are in a position to make sense of the genetic control systems.  Indeed, I have a project awaiting a student in The Institute next month that will compare the genome sequences of tomato Lycopersicon esculentum and potato Solanum tuberosum, both members of the Solanaceae along with Aubergine Solanum melongena and deadly-night-shade Atropa belladonna. You can see why I try to remember to use Latin names for species when you note that in English alone aubergine, brinjal, eggplant, melongene, garden egg, and guinea squash all refer to the same species.

The first species of flowering plants to be genome sequenced was Arabidopsis thaliana [see right] which trips so lightly off the tongue that you never need to know that the common name in English is mouse-ear cress.  It is the cause of a disconcerting thing that can happen to newbie searchers in sequence databases.  They ask for sequences from "mouse" not realising that the default search-term is "mouse*" where * is a wildcard, so they get their mouse sequences well shuffled with data from mouse  mouse-ear cress, Tragulus javanicus (Lesser mouse deer),  Microcebus murinus (Gray Mouse Lemur), and Rhabdomys pumilio (Four-striped grass mouse).  How we larfed at the tyros before sending them off for the glass hammer.

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