Mystery of plant’s roots targeted by OWU project

Ohio Wes­leyan Uni­ver­sity fac­ulty mem­ber Chris Wolver­ton exam­ines dishes con­tain­ing the plant Ara­bidop­sis thaliana, the focus of a paper he and three OWU stu­dents pub­lished in the Amer­i­can Jour­nal of Botany. (Gazette | Paul Comstock)

PAUL COMSTOCK

Staff Writer

An Ohio Wes­leyan Uni­ver­sity fac­ulty mem­ber and three stu­dents have pub­lished a paper in a sci­en­tific jour­nal that helps explain one of the many rea­sons plants behave the way they do.

Direct­ing the study was Chris Wolver­ton, Ph.D., an asso­ciate pro­fes­sor of botany and microbiology.

The paper, “Low Phos­phate Alters Lat­eral Root Set­point Angle and Grav­it­ro­pism,” appears in the Jan­u­ary edi­tion of the Amer­i­can Jour­nal of Botany.

Its title might be dry sci­en­tific ter­mi­nol­ogy, but Wolver­ton said the work some­day could be part of a larger body of research that yields big div­i­dends in agriculture.

The study focused on sideways-growing lat­eral roots, which make up the vast major­ity of a plant’s root sys­tem, of Ara­bidop­sis thaliana seedlings.

“What were hop­ing to under­stand,” he said, “in the big pic­ture … is how plants reg­u­late how and where they grow. These lat­eral roots that come out, they all choose a dif­fer­ent angle and they stick to that angle for a period of time. If you move them away from that angle they find it again. They go back to it. So what we’re try­ing to do is fig­ure out what is the sys­tem, what is the series of switches and reg­u­la­tors inside the plant, in the mol­e­c­u­lar sense, that’s guid­ing the plant to that par­tic­u­lar angle.”

The small plants were grown in Petri dishes to gauge their roots’ reac­tion to the loca­tion of phos­phate, a plant nutri­ent. The plants were watched to see if the angle of their lat­eral roots changed in reac­tion to the phosphate.

“We’re inter­ested in the kind of raw mol­e­c­u­lar sig­nals that tune this par­tic­u­lar angle,” he said, “and we spec­u­lated that because roots grow at dif­fer­ent angles under dif­fer­ent nutri­ent con­di­tions that maybe if we altered nutri­ent sta­tus, we should see a dif­fer­ence in the over­all angle that the root sys­tem sets itself at, and that’s in fact what we saw.”

Under­stand­ing the behav­ior some­day might enable sci­ence to con­trol it, Wolver­ton said.

“For exam­ple, for plants to be drought-tolerant, we could tune it so their roots went deeper in the soil rather than stay­ing closer to the sur­face. There’s a greater prob­a­bil­ity that water is deeper. For grow­ing in con­di­tions where there’s a dif­fer­ent soil pro­file, for exam­ple, if there are lots of phos­phate ions toward the top of the pro­file and not much toward the bot­tom. Maybe you’d want a vari­ety that’s been more tuned to stay hor­i­zon­tal rather than going more vertical.”

He empha­sized such tech­nol­ogy is many years in the future, but “if you pic­ture lat­eral roots as kind of the foot sol­diers of the root sys­tem, you can imag­ine that maybe under a given sit­u­a­tions the gen­eral would want to rede­ploy troops to a new pocket of soil or to a new front in the bat­tle.” Those changes, he said, some­day might help plants thrive under stress­ful conditions.

Ara­bidop­sis thaliana is being stud­ied by as many as 1,000 labs world­wide, he said,and its genome has been sequenced. Wolver­ton used sam­ples from Ohio State Uni­ver­sity, which were made to order.

“We can order a defect in any gene we want and test its effect. We made use of that in this study. We ordered some plants that were mutant for phos­phate car­ri­ers,” he said.

That made Ara­bidop­sis more sen­si­tive to vari­ables in the study, he said, and under dif­fer­ent con­di­tions the plants responded the same way.

A poten­tial goal of such work, he said, would be iden­ti­fy­ing “the mol­e­c­u­lar switch that causes the root to swith this angle … some mol­e­cule, some gene that encodes a pro­tein that the plant … some­thing that’s inte­grat­ing all of these cues.”

Stu­dents work­ing with Wolver­ton on the project were Evan Bai, Bhavna Murali and Kevin Bar­ber. All three have since grad­u­ated and are pur­su­ing doc­toral studies.

Wolver­ton earned his doc­tor­ate at the Ohio State Uni­ver­sity and joined the Ohio Wes­leyan fac­ulty in 2002.

pcomstock@civitasmedia.com