title: Incomplete transfer of accessory loci influencing SbMATE expression underlies genetic background effects for aluminum tolerance in sorghum.
abstract: Impaired root development caused by aluminum (Al) toxicity is a major cause of grain yield reduction in crops cultivated on acid soils, which are widespread worldwide. In sorghum, the major Al-tolerance locus, AltSB , is due to the function of SbMATE, which is an Al-activated root citrate transporter. Here we performed a molecular and physiological characterization of various AltSB donors and near-isogenic lines harboring various AltSB alleles. We observed a partial transfer of Al tolerance from the parents to the near-isogenic lines that was consistent across donor alleles, emphasizing the occurrence of strong genetic background effects related to AltSB . This reduction in tolerance was variable, with a 20% reduction being observed when highly Al-tolerant lines were the AltSB donors, and a reduction as great as 70% when other AltSB alleles were introgressed. This reduction in Al tolerance was closely correlated with a reduction in SbMATE expression in near-isogenic lines, suggesting incomplete transfer of loci acting in trans on SbMATE. Nevertheless, AltSB alleles from the highly Al-tolerant sources SC283 and SC566 were found to retain high SbMATE expression, presumably via elements present within or near the AltSB locus, resulting in significant transfer of the Al-tolerance phenotype to the derived near-isogenic lines. Allelic effects could not be explained by coding region polymorphisms, although occasional mutations may affect Al tolerance. Finally, we report on the extensive occurrence of alternative splicing for SbMATE, which may be an important component regulating SbMATE expression in sorghum by means of the nonsense-mediated RNA decay pathway.
authors.affiliation: Embrapa Maize and Sorghum, Road. MG 424, km 65, 35701-970, Sete Lagoas, Minas Gerais, Brazil.|Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, 31270-901, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Janaina O
authors.initials: JO
authors.lastname: Melo
authors.affiliation: Embrapa Maize and Sorghum, Road. MG 424, km 65, 35701-970, Sete Lagoas, Minas Gerais, Brazil.|Departamento de Biologia Geral, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, 31270-901, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Ubiraci G P
authors.initials: UG
authors.lastname: Lana
authors.affiliation: US Department of Agriculture - Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Piñeros
authors.affiliation: Embrapa Maize and Sorghum, Road. MG 424, km 65, 35701-970, Sete Lagoas, Minas Gerais, Brazil.
authors.forename: Vera M C
authors.initials: VM
authors.lastname: Alves
authors.affiliation: Embrapa Maize and Sorghum, Road. MG 424, km 65, 35701-970, Sete Lagoas, Minas Gerais, Brazil.
authors.forename: Claudia T
authors.initials: CT
authors.lastname: Guimarães
authors.affiliation: US Department of Agriculture - Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Jiping
authors.initials: J
authors.lastname: Liu
authors.affiliation: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Silin
authors.initials: S
authors.lastname: Zhong
authors.affiliation: US Department of Agriculture - Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Cornell University, Ithaca, NY, 14853, USA.|Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Zhangjun
authors.initials: Z
authors.lastname: Fei
authors.affiliation: US Department of Agriculture - Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Lyza G
authors.initials: LG
authors.lastname: Maron
authors.affiliation: Embrapa Maize and Sorghum, Road. MG 424, km 65, 35701-970, Sete Lagoas, Minas Gerais, Brazil.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Schaffert
authors.affiliation: US Department of Agriculture - Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Cornell University, Ithaca, NY, 14853, USA.
authors.forename: Leon V
authors.initials: LV
authors.lastname: Kochian
authors.affiliation: Embrapa Maize and Sorghum, Road. MG 424, km 65, 35701-970, Sete Lagoas, Minas Gerais, Brazil.
authors.forename: Jurandir V
authors.initials: JV
authors.lastname: Magalhaes
mesh_terms: D017398:Alternative Splicing; D000535:Aluminum / Q000633:toxicity*; D001483:Base Sequence; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D014644:Genetic Variation; D018745:Genome, Plant; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D045868:Sorghum / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D000535:Aluminum