title: Tetraploidy Enhances Boron-Excess Tolerance in Carrizo Citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.).
abstract: Tetraploidy modifies root anatomy which may lead to differentiated capacity to uptake and transport mineral elements. This work provides insights into physiological and molecular characters involved in boron (B) toxicity responses in diploid (2x) and tetraploid (4x) plants of Carrizo citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.), a widely used citrus rootstock. With B excess, 2x plants accumulated more B in leaves than 4x plants, which accounted for their higher B uptake and root-to-shoot transport rates. Ploidy did not modify the expression of membrane transporters NIP5 and BOR1 in roots. The cellular allocation of B excess differed between ploidy levels in the soluble fraction, which was lower in 4x leaves, while cell wall-linked B was similar in 2x and 4x genotypes. This correlates with the increased damage and stunted growth recorded in the 2x plants. The 4x roots were found to have fewer root tips, shorter specific root length, longer diameter, thicker exodermis and earlier tissue maturation in root tips, where the Casparian strip was detected at a shorter distance from the root apex than in the 2x roots. The results presented herein suggest that the root anatomical characters of the 4x plants play a key role in their lower B uptake capacity and root-to-shoot transport.
  
  
  CONCLUSIONS
  Tetraploidy enhances B excess tolerance in citrange CarrizoExpression of NIP5 and BOR1 transporters and cell wall-bounded B are similar between ploidiesB tolerance is attributed to root anatomical modifications induced by genome duplicationThe rootstock 4x citrange carrizo may prevent citrus trees from B excess.
authors.affiliation: Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias Moncada, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Ruiz
authors.affiliation: Centro de Citricultura y Producción Vegetal, Instituto Valenciano de Investigaciones Agrarias Moncada, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Quiñones
authors.affiliation: Centro de Citricultura y Producción Vegetal, Instituto Valenciano de Investigaciones Agrarias Moncada, Spain.
authors.forename: Belén
authors.initials: B
authors.lastname: Martínez-Alcántara
authors.affiliation: Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias Moncada, Spain.
authors.forename: Pablo
authors.initials: P
authors.lastname: Aleza
authors.affiliation: UMR AGAP, Centre de Coopération Internationale en Recherche Agronomique Pour le Développement Montpellier, France.
authors.forename: Raphaël
authors.initials: R
authors.lastname: Morillon
authors.affiliation: Centro de Protección Vegetal y Biotecnología, Instituto Valenciano de Investigaciones Agrarias Moncada, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Navarro
authors.affiliation: Centro de Citricultura y Producción Vegetal, Instituto Valenciano de Investigaciones Agrarias Moncada, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Primo-Millo
authors.affiliation: Centro de Citricultura y Producción Vegetal, Instituto Valenciano de Investigaciones Agrarias Moncada, Spain.
authors.forename: Mary-Rus
authors.initials: MR
authors.lastname: Martínez-Cuenca
keywords: 4x; BOR1; Casparian strip; NIP5; citrus; poliploidy; rootstock