In 2010, the gene controlling pea flower colour – first studied by Gregor Mendel 150 years earlier – was identified by researchers from New Zealand and overseas.
Mendel’s experiments on peas
Key principles ofwere developed from Gregor Mendel’s ground-breaking experiments on inheritance in the 1860s. Mendel cross-bred pure lines of pea plants (Pisum sativum) and recorded the inheritance of visible traits, such as flower colour, stem length, pod shape and pod colour.
Mendel’s traits in the 21st century
In 2010, a team of researchers from Plant & Food Research in New Zealand, along with collaborators in the UK, France and the US, identified thethat controls flower colour in peas, one of the 7 traits that Mendel followed.
Purple flowers accumulatepigment molecules, whereas white flowers do not. For this reason, the researchers speculated that the gene they were looking for was likely to regulate anthocyanin .
Finding the gene for pea flower colour
The researchers knew approximately where the gene was in the pea– its – because of genetic markers close by. Unfortunately, there wasn’t much information available about the pea genes in this region, and a full genome sequence wasn’t available. By comparing pea genes with genes in a similar region in plants with fully sequenced genomes, like barrel clover and petunia, they found a gene that was likely to affect anthocyanin pigment production.
A gene controlling pigment manufacture
When the researchers looked at the switch on expression of genes. The pea plants with this version of the gene don’t make anthocyanin pigments and have white flowers.sequence of the same gene in white-flowering pea plants. they noticed a difference in just 1 . This single base change, from G to A, stops the gene being made into protein, so it can’t
Confirming the gene function
To test the gene’s function, the researchers expressed the gene transiently in pea petals. They did this using– firing copies of the gene construct into pea petals from a . In areas of the petal where the gene was expressed, the flowers accumulated anthocyanin pigment and were coloured purple.
Identifying Mendel’s other pea genes
This is the 4th of the Mendel’s peagenes to be identified. Researchers have already identified the genes behind plant size, pea seed colour and seed shape.
Anthocyanins: important pigment molecules
Anthocyanin is responsible for red, blue and purple colours seen in many plants. Anthocyanin pigments are antioxidants – they mop up DNA-damaging free radicals that are released during , particularly during high light. This minimises damage to the plant’s DNA.
If we eat plants containing anthocyanin, the pigment molecules seem to make our own systems more effective. This is part of the reason why having a mixed diet of colourful fruits and vegetables is good for our health. This is also why plant breeders are interested in breeding fruits that contain more anthocyanin pigments. Find out more about this in resources on breeding red-fleshed apples.
The full article on the Identification of Mendel’s white flower character is freely available at PLoS One
Video of Roger Hellens explaining the discovery of the gene controlling pea flower colour.