2 Dec 2021

Scientists choose cryopreservation to store plant material for decades

11:45 am on 2 December 2021

Some of New Zealand's native plants are undergoing cryopreservation freezing as scientists explore conservation techniques that could protect at-risk species for future generations.

Liya Mathew from Plant and Food Research working on a cryopreservation project

Liya Mathew from Plant and Food Research working on a cryopreservation project. Photo: Supplied

The work has been sparked by the plant disease myrtle rust, which has been spreading rapidly across the country since it was first identified in 2017.

The fungal disease attacks plants in the myrtaceae or myrtle family, including pōhutukawa, rātā, mānuka and swamp maire.

Scientists at Plant and Food Research are concerned this could lead to the extinction of important plant genetic resources and to counter this threat, they are looking at the effectiveness of seed banking, tissue cultures, plant cuttings, and pollen and embryo cryopreservation.

Science team leader for germplasm conservation Dr Jayanthi Nadarajan said until now, there had been little research on long-term conservation of myrtle species in Aotearoa outside their natural environment.

Nadarajan said the benefit of cryopreservation was that plant material could be stored for decades, or centuries, without there being changes in its genetic components.

She said at many international seed banks the standard temperature for storage was -20 degrees celsius, but lately it had found that not all seeds could be banked at that temperature, as some lost their viability very quickly.

"So we found that lowering the temperature further to -196C, or the cryopreservation temperature, will extend the storage life of this seed. This is particularly critical for wild species, which are quite rare, [and] threatened in nature. So we have to have the long term conservation technique in place."

She said to understand the importance of this work one only needed to look to Australia, where myrtle rust had caused the extinction of some localised species.

In New Zealand, scientists had already seen the adverse effects of this disease on ramarama, where the species was already disappearing from natural populations. They'd also recently noticed myrtle rust on swamp maire seeds, which meant these plants wouldn't be able to produce seedlings, Dr Nadarajan said.

"If this scenario continues, this will lead to species extinction. Despite the high risk of extinction to New Zealand myrtaceae species, limited information is available on seed biology, ecology, [and] population of most of the species, which is hampering the conservation effort," she said.

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