Converting flowers into branches

28 March 2013

A newly named gene in the grass species Brachypodium, called MORE SPIKELETS1, has been found by Dr Mary Byrne to convert flowers into branches. A stunning scanning electron micrograph image of this work has made the cover of this month's Plant Physiology.

Scanning electron micrograph image of Brachypodium features on the cover of Plant Physiology
Scanning electron micrograph image of Brachypodium features on the cover of Plant Physiology

It might look like piece of abstract art or a sculpture for the garden but this stunning photo actually represents the beginnings of plant growth. What you are looking at is the growing point of a plant. This includes a number of meristems (coloured yellow), which are somewhat analogous to stem cells. The different bumps and creases emerging from the meristems (coloured green) develop into the mature parts of the Brachypodium grass head or 'spike'.

The plant development research behind this cover image was carried out by the School of Biological Sciences' Mary Byrne. "We established a mutagenesis population of Brachypodium to look for developmental mutants," said Mary. "The ones we're interested in effect the arrangement of flowers on the reproductive part of the plant." And four mutations in particular were the subject of their Plant Physiology paper.

Of those four mutants, three had defects that reduced the numbers of flowers produced. The other mutant, more spikelets1 converted spikelets, the basic unit in grasses that carries flowers, into branches. That is not to say that the mature grass heads suddenly convert into branches, rather the cells that would normally be fated to develop into spikelets mature instead into branches.

So why do we care about spikelets, meristems, flowers and mutants of Brachypodium? We care because Brachypodium is the model plant for agriculturally important grasses like wheat, barley and rye. And an understanding of the development of these grasses (especially the parts of them we eat) may lead to the development of higher-yielding varieties.

Plus the pictures are really cool!