B.T.Meatyard at warwick.ac.uk
Thu Sep 20 09:21:43 EST 2001
I have tried unsuccessfully over the years to demonstrate biosynthetic
pathways leading to colour production in Antirrhinum flowers. The principle
is that white flowers are white because the biosynthetic pathway leading to
anthocyanidin production is blocked in one of 2 genes determining enzymes
in the pathway. The blocking gene can be identified by the addition of a
flavonol intermediate (dihydroquercetin) to an excised white flower via its
stalk. If the flower subsequently develops colour the block is in the 2nd
gene, if it fails to produce colour the block is in the first gene.
That's the story (according to June New, J.Biol.Ed (1986) 20 p229-230) but
I've never managed to get it to work and I haven't been able to contact
June New to see if there are tricks of the trade that aren't apparent in
The reason for doing this is to demonstrate to students that white flowers
may be white for more than one reason and thus represent biodiversity that
cannot be observed simply by looking at the outward phenotype.
I've used dihydroquercetin from Sigma, but since no chemical formula was
given in the paper it may be that the name covers more than one structure
and I'm not discounting having the wrong 'dihydroquercetin'!
Can anyone throw any light on this or suggest alternatives that would
enable differences between apparently similar plants to be visualised in
such a way (without resorting to DNA technology)? I want this to be simple
and effective enough to be usable in high schools in UK.
Any suggestions or advice welcome.
Environmental Sciences Research and Education Unit
Warwick Institute of Education
University of Warwick
Email: barry.meatyard at warwick.ac.uk
Tel: 44 (0) 2476 524228
Fax: 44 (0) 2476 523237
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