Seed banks will not save over third of crit­i­cally en­dan­gered plants

Tehran Times - - SOCIETY -

More than a third of crit­i­cally en­dan­gered plant species can­not be saved from ex­tinc­tion by freez­ing them in seed banks, sci­en­tists have warned.

Projects such as the Sval­bard Global Seed Vault have been set up to pro­tect the world’s plant di­ver­sity from dooms­day events rang­ing from nu­clear war to ex­treme cli­mate change.

In the UK, Kew’s Mil­len­nium Seed Bank is aim­ing to pro­tect three quar­ters of the world’s threat­ened plant species within the next two years.

“Ex-situ con­ser­va­tion of plants is more crit­i­cal than ever, with many threats to plant pop­u­la­tions in­clud­ing cli­mate change, habi­tat con­ver­sion and plant pathogens, we need to make sure we’re do­ing all we can to con­serve the most im­por­tant and threat­ened species,” said Dr John Dickie, head of seed col­lec­tions at Kew.

How­ever, for many of the most at-risk plants, con­ven­tional stor­age tech­niques will not work, and a team of Kew sci­en­tists has called for re­search into al­ter­na­tive mea­sures to en­sure their sur­vival.

In to­tal around 8 per cent of all plant species can­not be banked by drying and freez­ing their seeds, in­clud­ing trees like oaks and horse chest­nuts, and foods in­clud­ing man­gos and av­o­ca­dos.

These seeds are re­cal­ci­trant, mean­ing they do not sur­vive the drying process. In a new pa­per pub­lished in the jour­nal Na­ture Plants, the re­searchers es­ti­mated that 36 per cent of the plants at the great­est risk of ex­tinc­tion are re­cal­ci­trant.

They also noted that tree seeds were par­tic­u­larly likely to die fol­low­ing at­tempts to dry and freeze them, with around a third deemed “un­bank­able”.

Us­ing this anal­y­sis Dr Dickie and for­mer col­league Dr Sarah Wyse were able to pre­dict that the tar­get of pre­serv­ing 75 per cent of threat­ened species by 2020 is prac­ti­cally im­pos­si­ble.

With num­bers of un­suit­able seeds par­tic­u­larly high among en­dan­gered species, the sci­en­tists rec­om­mended in­vest­ing in an al­ter­na­tive tech­nique known as cry­op­reser­va­tion.

The method in­volves re­mov­ing a seed’s em­bryo and then us­ing liq­uid ni­tro­gen to freeze it at -196C, far colder than he con­ven­tional seed bank tem­per­a­ture of -20C.

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