Ge­net­i­cally en­gi­neered trees for bio­fuel pro­duc­tion

Australian Forests and Timber - - BIOENERGY -

RE­SEARCHERS HAVE ge­net­i­cally en­gi­neered po­plar trees with lignin that breaks down more eas­ily, open­ing the door to cheaper bio­fu­els and wood pulp that re­quire only a frac­tion of the en­ergy and chem­i­cals to pro­duce, ac­cord­ing to a piece in The Van­cou­ver Sun

By in­sert­ing a piece of code iso­lated from a Chi­nese herb into the DNA of a po­plar tree, sci­en­tists at the Univer­sity of Bri­tish Columbia, Michi­gan State and Univer­sity of Wis­con­sin-Madi­son have pro­duced a tree de­signed for easy de­con­struc­tion.

The code al­ters the chem­istry of some of the bonds that hold to­gether lignin, the or­ganic poly­mer glue that makes trees tough and rigid and pro­tects the en­ergy-rich cel­lu­lose within cells.

The ge­net­i­cally en­gi­neered poplars are ev­ery bit as strong as nor­mal poplars while they are liv­ing, but when pro­cessed the lignin “un­zips” where the al­tered bonds oc­cur in the poly­mer chain.

Re­mov­ing nat­u­rally oc­cur­ring lignin for the pro­duc­tion of bioethanol and pa­per prod­ucts re­quires caus­tic chem­i­cals and high heat, about 170 C for sev­eral hours, ac­cord­ing to an on­line ar­ti­cle in the jour­nal Science. Zip-lignin falls apart in a mild al­ka­line so­lu­tion at just 100 C.

The group’s ini­tial ef­forts to re­duce lignin con­tent re­sulted in trees that were stunted, weak and sus­cep­ti­ble to pests. The key was not less lignin, but sim­ply to al­ter the lignin slightly so it would come apart eas­ily when prompted.

Ge­nomics — the anal­y­sis of the com­plete DNA code of or­gan­isms — makes it pos­si­ble to iden­tify plants that have cer­tain de­sir­able char­ac­ter­is­tics and use that in­for­ma­tion to speed con­ven­tional se­lec­tive breed­ing, but also to iden­tify spe­cific pieces of ge­netic code that can be al­tered, sup­pressed or aug­mented to pro­duce plants bet­ter suited to hu­man needs.

GE po­plar could be grown on plan­ta­tions on agri­cul­tural land un­suited to food crops and pro­vide a source of bio­fuel that does not com­pete with food crops.

To pre­vent “gene flow” to wild poplars, the GE trees could be made ster­ile or har­vested be­fore they at­tain re­pro­duc­tive ma­tu­rity.

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