A King Protea in the Silvermine Nature Reserve in Cape Town, South AfricaCredit: Kim Cloete
The whole genome of the king protea (Protea cynaroides) has been sequenced, a first for an indigenous plant in the Cape Floral Kingdom. At about 1.18 gigabases (Gb) long there are more than 1.18 billion combinations of the A, C, T and G, 'letters' of the DNA alphabet, contained in the 12 chromosomes that make up its genome a new study in The Plant Journal says.
The study also provides valuable clues about the evolutionary past of the country’s national flower. It shows that in the distant past ancestors of the Protea genus and larger Proteaceae family lost the specific genes that allow many other plants to have a mutually beneficial, nutrient-extracting relationship — arbuscular mycorrhiza symbiosis (or AM symbiosis) — with soil fungi growing on their roots.
“It means they've lost the ability to 'communicate' with fungi,” project leader, Eshchar Mizrachi, of the University of Pretoria's (UP) Department of Biochemistry, Genetics and Microbiology and the Forestry and Agricultural Biotechnology Institute (FABI) explains.
Proteaceae rely on cluster roots to extract as many nutrients as possible from even the poorest soils, and to better ‘mine’ for growth enhancing phosphorus.
It is still unclear whether this happened before or after cluster roots emerged in this plant family. “Knowledge about the genome allowed us to explain why they are unable to make the AM symbiosis association," says Mizrachi.
“It seems, as confirmed again by the Protea genome, that polyploidy confers some evolutionary advantage at times of environmental turmoil or stress. How that works exactly, is the topic of much further research,” adds co-researcher, Yves Van de Peer, who holds joint positions at Ghent University and the VIB Centre for Plant Systems Biology in Belgium, UP and the Nanjing Agricultural University in China.
