The amazing resurrection bush Myrothamnus flabellifolia, (‘opstandingsplant’ in Afrikaans), occurs naturally in the northern half of South Africa (Limpopo, North-West, Gauteng, Mpumalanga and Kwa-Zulu Natal), as well as in other parts of southern Africa (Namibia, Zimbabwe, Kenya and Malawi).
The botanical name comes from the Greek: myron means ‘perfume’ and thamnus, means ‘bush’, and flabellifolia means ‘with fan-like leaves’.
Despite this appropriate name, it’s not often seen in leaf and the fan-like leaves are seldom seen. This is because this plant has the amazing ability to dry out (losing up to 95% of its water) and appear to be dead when water is scarce and temperatures are high. However, it’s not dead, only dormant.
The resurrection bush has evolved to occupy a very inhospitable niche habitat. It grows in hot areas, in very shallow soils on rock slopes. The extensive roots grow into the cracks and fissures in the rock where water drains when it rains.
Photo: UCT News
Its native habitat in Southern Africa suffers frequent droughts, so the plant looks like a stack of dead sticks most of the time. However, it is so well adapted to these periods of drought that it can magically spring into life within hours of rain falling. The fan-like leaves unfurl and become green again, and resume normal metabolism, including photosynthesis.
The biochemistry of life is critically dependent on stable cellular structures and their associated proteins such as enzymes and other metabolites.
It is mind-boggling that all the plant’s cell membranes and vital life-supporting molecules are undamaged by severe desiccation. It is so remarkable, in fact, that M. flabellifolia is one of the very few woody vascular plants to have evolved the ability to resurrect, even after three years of dormancy.
Resurrected bush – Photo: La Plumeria
What does this plant have that protects the integrity of its cells during extreme desiccation? Jill Farrant, professor of molecular and cell biology at the University of Cape Town has been studying it over many years to find out.
“What makes resurrection plants in general and M. flabellifolia in particular – so special,” she explains, “is the remarkable toolbox of chemicals they use to survive the extreme water loss and heat that would kill any other plant”.
So how do resurrection plants come back to life? In their apparent death state these plants slow down their metabolism to the minimum. They ensure that cell structures are not damaged by the lack of water, by the loss of volume and by the presence of oxidizing substances which are typically produced during water stress. This requires the combined action of genetic, physiological and structural mechanisms that we are just starting to understand. Cells become smaller and the walls more flexible to accommodate the change in volume.
Photosynthetic apparatuses are dismantled, but their building materials are stored so that they can be rebuilt speedily as soon as water becomes available again.
Antioxidants, enzymes and other molecules are produced to neutralize free radicals, and carbohydrate metabolism is redirected to the production of sugars such as sucrose and trehalose. These, together with some special proteins, protect and maintain the shape of all the cellular structures, including DNA and organelles, with a role of combining features of a scaffold and a bubble wrap.
M. flabellifolia also contains the greatest number of antioxidants Farrant has ever seen in a plant, more so than better-known wonder plants like rooibos and Aloe vera. The antioxidants in M. flabellifolia protect cell membranes from damage at the microscopic level.
The remarkable ‘toolbox’ of chemicals in the resurrection plant has not escaped the indigenous people of Africa. For centuries they have been using the plant for its medicinal properties. When made into a tea or smoked, it is used for just about any ailment – including epilepsy, mental disorders, cough, pain, stroke, shingles, diabetes, hypertension, wounds, asthma, kidneys and chest ailments. Thankfully, harvesting of the resurrection plant for traditional medicines has so far been low-key and sustainable.
Resurrection plants and the future of food
Climate change could reduce maize yields across southern Africa by as much as 30% by 2030, according to the UN Environment Programme.
Prof Farrant explained in a TED talk that cereals such as wheat, corn and rice, which are the basis of global food supply, are annual plants that require a wet season in order to grow and fruit. Since the world’s population is rapidly increasing (now over eight billion) while arable wetlands are shrinking because of climate change, it is clear that drought-tolerant crops are required to ensure global food security.
Many of the genes controlling the “resurrection” processes described above have only been identified recently. Interestingly, they are not only common among resurrection plants, but are also found in any other vascular plant. There is indeed at least one stage in each plant’s life which is specifically intended to make the plant enter a dormancy state, dehydrate and wait for the right moment to “come back to life” – the production of the seed.
Plants already own the genetic setup required for facing dehydration, but these mechanisms are exclusively active during the embryonic stage and are not found in adult plant organs, such as leaves.
The race is now on for researchers to produce new varieties of food plants in which the endogenous “resurrection genes” are activated in every part of the plant upon dehydration. These drought-tolerant crops might ensure a reliable food source in those territories where increasingly frequent poor rainy seasons could have severe social and economic consequences.