title: Hybrid weakness controlled by the dosage-dependent lethal (DL) gene system in common bean (Phaseolus vulgaris) is caused by a shoot-derived inhibitory signal leading to salicylic acid-associated root death.
abstract: Certain crosses of common bean (Phaseolus vulgaris) result in temperature-dependent hybrid weakness associated with a severe root phenotype. This is controlled by the interaction of the root- and shoot-expressed semidominant alleles dosage-dependent lethal 1 (DL(1)) and DL(2), which communicate via long-distance signaling. Previously, apparent reciprocal effects on root growth and the restoration of normal root growth by exogenous sucrose led to the hypothesis that the dosage-dependent lethal (DL) system may control root-shoot carbon partitioning. Here, recombinant inbred lines were used to map the DL loci and physiological and biochemical analysis, including metabolite profiling, was used to gain new insights into the signaling interaction and the root phenotype. It is shown that the DL system does not control root-shoot carbon partitioning and that roots are unlikely to die from carbon starvation. Instead, root death likely occurs by defense-related programmed cell death, as indicated by salicylic acid accumulation. DL(2)-expressing cotyledons supply a potent inhibitory signal that is sufficient to cause such death in DL(1)-expressing roots. These data implicate the DL system in defense-related signaling and provide support for the recent hypothesis of defense-related autoimmunity as a potential isolating mechanism in plant speciation, in particular, setting a precedence for the potential roles of long-distance signaling and temperature dependence.
authors.affiliation: Max-Planck Institute of Molecular Plant Physiology, Am Mühlenburg 1, 14476 Golm, Germany.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Hannah
authors.affiliation: Max-Planck Institute of Molecular Plant Physiology, Am Mühlenburg 1, 14476 Golm, Germany.
authors.forename: K Melanie
authors.initials: KM
authors.lastname: Krämer
authors.affiliation: INRA, Institut de Biotechnologie des Plantes, UMR-CNRS 8618, LPPM, bât. 630, Université Paris-Sud, 91405 Orsay, France.
authors.forename: Valerie
authors.initials: V
authors.lastname: Geffroy
authors.affiliation: Max-Planck Institute of Molecular Plant Physiology, Am Mühlenburg 1, 14476 Golm, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kopka
authors.affiliation: Centro Internacional de Agricultura Tropical, AA 6713, Cali, Colombia.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Blair
authors.affiliation: Max-Planck Institute of Molecular Plant Physiology, Am Mühlenburg 1, 14476 Golm, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Erban
authors.affiliation: Department of Horticultural Sciences, and Plant Molecular and Cellular Biology Program, 1143 Fifield Hall, University of Florida, Gainesville, FL 32611-0690, USA.
authors.forename: C Eduardo
authors.initials: CE
authors.lastname: Vallejos
authors.affiliation: Biologisches Institut, Abt. Botanik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany.
authors.forename: Arnd G
authors.initials: AG
authors.lastname: Heyer
authors.affiliation: School of Biology.
authors.forename: Francis E T
authors.initials: FET
authors.lastname: Sanders
authors.affiliation: Institute of Membrane and Systems Biology and.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Millner
authors.affiliation: Institute of Integrative and Comparative Biology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Pilbeam
mesh_terms: D050260:Carbohydrate Metabolism; D002874:Chromosome Mapping; D018548:Cotyledon / Q000502:physiology; D049810:Genetic Speciation; D006824:Hybridization, Genetic / Q000502:physiology; D027805:Phaseolus / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D018520:Plant Shoots / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D020156:Salicylic Acid