Preserving plant genetic resources

Nari, Normal

The National, Tuesday June 16th, 2015

 By Toshiro Shigaki

With ongoing climate change, urbanisation, and the trend toward cultivating only a few select varieties, crop diversity is being lost at an accelerating pace.  

Facing this challenge, National Agricultural Research Institute (NARI) commits itself to preserving plant genetic resources for national food security.  

Crop diversity can be preserved in a number of ways.  NARI manages “gene banks” where representative crop lines are maintained (ex situ collections) with genetic and morphological information available for each accession.  

Such collections are, however, prone to natural disasters such as flooding, drought, and pest and disease attacks.  

A safer alternative to preserve plant genetic resources is to use tissue culture (in vitro collections), which can be costly and technically more demanding.

In 2008, a seed bank, with a concept never imagined before, started its operation.  

This new facility is called Svalbard global seed vault, located on a remote Spitsbergen Island in the Svalbard Archipelago in the Arctic Norway.  

The storage facility is located 120m inside a sandstone mountain under the permafrost cover, with no known tectonic activity.  

The stored seeds are stably maintained at -18°C by power generated from locally mined coal.  

The beauty of the Arctic location of this seed bank is that even if the power fails, the low temperature is still maintained at least for several weeks before it reaches its natural temperature of the sandstone mountain, -3°C.  

The location is also far from any potential conflict, and vandalism or terrorism is unlikely.  

Such events are not just imagined, but very real.  

In the past, for example, seed banks have been lost in wartime Afghanistan and Iraq.  

With Svalbard global seed vault, even if a major world war breaks out and most of the human population is wiped out from the surface of the planet, the surviving humans can make use of the seeds for their food needs.

The facility is operated by Global Crop Diversity Trust and the Norwegian Government. 

Existing seed banks can send their duplicate seeds to the seed vault for safekeeping.  

The seeds stored in the seed vault remain the property of the donors and there is no fee to end users to deposit seeds.  

With assistance from the Secretariat of the Pacific Community (SPC), NARI is preparing to send the first batch of seeds to the seed vault later this year.

To preserve seeds in the low temperature, the physiology of seeds must be understood first.  

There are two types of seeds in terms of cold storability: orthodox and recalcitrant.  

Orthodox seeds can survive the subfreezing temperature and can stay viable for over hundreds of years, while recalcitrant seeds are intolerant to the low temperature.  

Unfortunately, most tropical seeds are thought to be recalcitrant, although the orthodox/recalcitrant status of most Pacific seeds is unknown.  

Therefore, it will be necessary to assess the cold storability of all the seeds important for the Pacific.  

Nonetheless, it is likely that the seeds of sweet potato, banana, and aibika are orthodox.  

These will be the first seeds to be deposited in Svalbard.  

Other seeds will be deposited after the status has been carefully assessed.

PNG is a centre of origin of many crops and their wild relatives.  

Banana is one such plant.  

As a vegetatively propagated crop, cultivated bananas are constantly under threat from pests and diseases due to their low genetic diversity, and breeders have to resort to unconventional methods to develop new varieties.  

These include the use of somaclonal variation and mutation breeding.  

Genetic engineering of banana is considered a safe option, in contrast to other crops, because of its sterility.  

The chance of polluting the gene pool of banana is extremely low.

Besides these three options, it is possible to develop new banana varieties using wild bananas by conventional crossing.  

Selected wild banana species and varieties can be crossed, and the seeds can be screened for desired varieties.  

It should be noted that PNG has a rich diversity of wild bananas, yet they are not very well studied and may be lost before they are even documented.

NARI scientists are currently collecting wild banana seeds from across the country for genetic preservation in Laloki and Bubia, as well as for the deposition in the Svalbard Global Seed Vault.