Seeds of the fu­ture

Molec­u­lar bi­ol­ogy and an old Soviet seed­bank may hold the key to feed­ing a warm­ing world. FIONA MCMIL­LAN reports.

Cosmos - - Special Feature - BROUGHT TO YOU BY THE AUS­TRALIAN COUN­CIL OF DEANS OF AGRI­CUL­TURE

How do you find seeds that will thrive in the cli­mate of the fu­ture? Robert Shar­wood doesn’t have a time ma­chine, but he does have ac­cess to a very old seed bank and a glasshouse that can sim­u­late fu­ture tem­per­a­tures and car­bon diox­ide lev­els. For an agri­cul­tural sci­en­tist, that’s the next best thing.

If all goes to plan, Shar­wood and his col­leagues will breed crops that can cope with fu­ture droughts and heat­waves. They must work quickly, though: time is short.

Plant sci­en­tists around the world agree that global food se­cu­rity faces mul­ti­ple chal­lenges in the com­ing decades. In the first in­stance, cur­rent crop pro­duc­tion can’t keep up with im­pend­ing de­mand.

“We need to in­crease our pro­duc­tiv­ity by 70% by 2050 in our food crops to be sure we can feed our grow­ing pop­u­la­tion in the world,” says Shar­wood, who works in the ARC Cen­tre of Ex­cel­lence for Trans­la­tional Pho­to­syn­the­sis at the Aus­tralian Na­tional Univer­sity.

We’ve faced the threat of world hunger be­fore. In the mid-20th cen­tury, when the world pop­u­la­tion was just three bil­lion, it seemed it would soon be im­pos­si­ble to feed ev­ery­one. How­ever, Nor­man Bor­laug and fel­low sci­en­tists used se­lec­tive plant breed­ing to pro­duce more grain per acre.

Today, the global pop­u­la­tion is nearly 7.5 bil­lion and is likely to ap­proach 10 bil­lion by 2050. Mean­while, agri­cul­tural sci­en­tists are be­gin­ning to strug­gle with in­creas­ing yield in wheat and rice, which are the most crit­i­cal crops.

Each year im­prove­ments in yield de­cline, says Shar­wood. While we are ap­proach­ing a the­o­ret­i­cal limit on calo­rie pro­duc­tion, there is a more press­ing prob­lem.

“What’s re­ally im­pact­ing pro­duc­tion is the cli­mate ex­tremes,” says Shar­wood. “Over the last 10 years the in­ten­sity and fre­quency of heat­waves and droughts have in­creased dra­mat­i­cally.”

With ris­ing an­thro­pogenic car­bon diox­ide this is pre­dicted to only get worse. “It’s re­ally im­por­tant that we make our crops flex­i­ble to cope with th­ese ex­treme events,” he says.

Shar­wood and oth­ers are hop­ing to ac­com­plish this by en­sur­ing the heart of the pho­to­syn­the­sis en­gine in crop plants is as ro­bust as pos­si­ble.

Dur­ing pho­to­syn­the­sis, plants use sun­light to fix car­bon diox­ide into car­bo­hy­drate build­ing blocks which are es­sen­tial for plant growth.

An enzyme called ribu­lose-1,5bis­pho­s­phate car­boxy­lase/oxy­ge­nase (RUBISCO for short) plays a crit­i­cal role in the con­ver­sion of car­bon diox­ide to car­bo­hy­drate, and Shar­wood has spent much of his ca­reer in­ves­ti­gat­ing how RUBISCO be­haves dif­fer­ently in a va­ri­ety of plant species, par­tic­u­larly grasses.

Re­cently, when in­ves­ti­gat­ing na­tive Aus­tralian grasses, he and his col­leagues dis­cov­ered some­thing in­trigu­ing. Not only do dif­fer­ent na­tive grasses pos­sess vari­a­tions in their RUBISCO en­zymes, they also re­spond dif­fer­ently to tem­per­a­ture.

Shar­wood is now col­lab­o­rat­ing with Dr Gon­zalo Es­tavillo at CSIRO to find out if wheat va­ri­eties also dis­play such nat­u­ral vari­abil­ity. To ex­plore this pos­si­bil­ity, they needed to find a wide range of dif­fer­ent va­ri­eties of wheat from dif­fer­ent cli­mates. Thanks to a group of far­sighted, self­sac­ri­fic­ing Rus­sian sci­en­tists, Shar­wood and Es­tavillo found the per­fect re­source.

In the early 1920s, Rus­sia ex­pe­ri­enced famine af­ter its civil war. In an ef­fort to pre­vent an­other agri­cul­tural dis­as­ter, a young Rus­sian botanist named Niko­lai Vav­ilov trav­elled the world col­lect­ing seeds of wild wheat and other food crops. He and his col­leagues col­lected nearly 200,000 spec­i­mens, to pro­duce the largest seed bank the world had ever known.

Dur­ing World War II the city of Len­ingrad, where the seeds were stored, came un­der pro­longed siege from Ger­man forces. A group of sci­en­tists re­mained be­hind to pro­tect the col­lec­tion, and went hun­gry, re­fus­ing to con­sume any of the seeds. Ul­ti­mately, nine starved to death. Mean­while, dur­ing the Ly­senkoist back­lash against plant ge­net­ics un­der Stalin, Vav­ilov was sent to prison where he, too, died of star­va­tion.

Now, the Vav­ilov seeds could help feed the world.

The wheat lines in the col­lec­tion orig­i­nate from in­cred­i­bly di­verse habi­tats, says Shar­wood. He and Es­tavillo are ex­plor­ing how in­di­vid­ual wheat lines adapted to their cli­mates of ori­gin.

“At the mo­ment we’re just search­ing for nat­u­ral vari­a­tion in car­bon diox­ide fix­a­tion and pho­to­syn­the­sis prop­er­ties,” he says.

In a care­fully mon­i­tored glasshouse, they are grow­ing 60 Vav­ilov wheat lines from 11 dif­fer­ent bio­geo­graph­i­cal ori­gins. Early re­sults in­di­cate there is di­ver­sity in pho­to­syn­the­sis func­tion in the Vav­ilov lines, and Shar­wood is keen to see if this is due to dif­fer­ences in RUBISCO per­for­mance.

He also wants to know how much RUBISCO is present, be­cause lev­els can vary be­tween va­ri­eties. This is im­por­tant be­cause RUBISCO con­tains a sig­nif­i­cant amount of ni­tro­gen, and a lot of the ni­tro­gen in fer­tilis­ers ends up there. Thus, a wheat line with low lev­els of highly ef­fi­cient RUBISCO that func­tions well un­der higher tem­per­a­tures would let farm­ers re­duce fer­tiliser and wa­ter use, while im­prov­ing crop yields.

Shar­wood says that once they have a bet­ter understanding of the bio­chem­istry of the Vav­ilov lines, they can make pre­dic­tive mod­els to see which lines would be good can­di­dates for breed­ing with ex­ist­ing com­mer­cial wheat to pro­duce high-yield crops.

The crit­i­cal test will be de­vel­op­ing the new breeds, and grow­ing them over mul­ti­ple sea­sons in the cur­rent cli­mate. How­ever the ul­ti­mate goal, he says, is to test them un­der fu­ture cli­mates.

“We can use glasshouses to test fu­ture en­vi­ron­ments where we can sup­ple­ment car­bon diox­ide and dif­fer­ent tem­per­a­tures,” he says.

As ever, plant breed­ing re­quires patience. “It will take about seven years to de­velop a line that we can use,” he says.

This, says Shar­wood, is why they are work­ing on this now, be­cause time is a lux­ury global agri­cul­ture doesn’t have.

Sud­denly, 2050 doesn’t seem so far away.

CREDIT: NATALIA BATEMAN

Robert Shar­wood is breed­ing wheat to thrive in fu­ture cli­mates.

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