Pre­vi­ously un­known rice blast re­sis­tance iso­lated

Agriculture - - Contents - BY SHARON DURHAM

A NEVER-BEFOREde­scribed gene that gives rice re­sis­tance to a dis­ease that has been cost­ing about $66 bil­lion a year in global dam­age has been iso­lated by a team of sci­en­tists led by Agri­cul­tural Re­search Ser­vice (ARS) plant pathol­o­gist Yulin Jia. Rice blast, caused by the fun­gus Mag­na­porthe oryzae, re­sults in an­nual yield losses large enough to have fed 60 bil­lion peo­ple each year, ac­cord­ing to the team’s pa­per just pub­lished in the jour­nal Na­ture Com­mu­ni­ca­tions.

In the United States’ mid-south rice-growing re­gion, the cost of mit­i­gat­ing rice blast in­fec­tion with fungi­cide ap­pli­ca­tions can reach al­most $20 per acre; plus, the fun­gus may still cause sig­nif­i­cant yield loss de­pend­ing on the sus­cep­ti­bil­ity of each rice va­ri­ety and the de­gree of in­fec­tion at the time of fungi­cide ap­pli­ca­tion, ac­cord­ing to the U.S. De­part­ment of Agri­cul­ture’s (USDA) Eco­nomic Re­search Ser­vice.

Amaz­ingly, Ptr, the dis­ease re­sis­tance gene Jia and his team found, has a struc­ture that has not been seen in plants be­fore. It has been pre­vi­ously de­ployed un­know­ingly in blast-re­sis­tant rice cul­ti­vars be­cause it has been tightly linked to another dis­ease re­sis­tance gene, Pi-ta, which has a ge­netic struc­ture that is well-de­scribed in sci­en­tific lit­er­a­ture.

Ptr has es­sen­tially been liv­ing in the shadow of Pi-ta. “Our re­search was able to sep­a­rate the two genes and demon­strate that Ptr is in­de­pen­dently re­spon­si­ble for its own broad­spec­trum blast re­sis­tance with­out Pi-ta,” says Jia. “This will pro­vide a new strat­egy for de­vel­op­ing blast-re­sis­tant rice cul­ti­vars.” The full ge­nomic se­quence of the Ptr gene was put into GenBank for use by public re­searchers world­wide. (Agri­cul­tural Re­search Ser­vice)

Test­ing for rice blast re­sis­tance in ge­net­i­cally en­gi­neered rice plants is done in var­i­ous coun­tries. ARS plant pathol­o­gist Yulin Jia sam­ples a field in Colom­bia for the dis­ease. (Photo by Fer­nando Cor­rea)

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