RESUMEN
A mutant line, bifurcate flower truss (bif), was recovered from a tomato genetics programme. Plants from the control line produced a mean of 0.16 branches per truss, whereas the value for bif plants was 4.1. This increase in branching was accompanied by a 3.3-fold increase in flower number and showed a significant interaction with exposure to low temperature during truss development. The control line and bif genomes were resequenced and the bif gene was mapped to a 2.01 Mbp interval on chromosome 12; all coding region polymorphisms in the interval were surveyed, and five candidate genes displaying altered protein sequences were detected. One of these genes, SlMAPK1, encoding a mitogen-activated protein (MAP) kinase, contained a leucine to stop codon mutation predicted to disrupt kinase function. SlMAPK1 is an excellent candidate for bif because knock-out mutations of an Arabidopsis orthologue MPK6 were reported to have increased flower number. An introgression browser was used to demonstrate that the origin of the bif genomic DNA at the BIF locus was Solanum galapagense and that the SlMAPK1 null mutant is a naturally occurring allele widespread only on the Galápagos Islands. This work strongly implicates SlMAPK1 as part of the network of genes controlling inflorescence branching in tomato.
Asunto(s)
Regulación de la Expresión Génica de las Plantas , Inflorescencia/crecimiento & desarrollo , Proteína Quinasa 1 Activada por Mitógenos/genética , Proteínas de Plantas/genética , Solanum lycopersicum/genética , Genes de Plantas , Inflorescencia/genética , Solanum lycopersicum/crecimiento & desarrollo , Solanum lycopersicum/metabolismo , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteínas de Plantas/metabolismoRESUMEN
Nine Phyllachora species found on hosts belonging to the family Myrtaceae native to the Brazilian Cerrado were described and illustrated. We sequenced nuc rDNA internal transcribed spacer barcode regions for representatives of seven species and conducted phylogenetic analyses, which provided strong support for four new species that we describe as Phyllachora cerradensis, P. ermidensis, P. furnasensis, and P. myrciariae. Catacauma nigerrimum was recombined into P. nigerrima, and a key to the common Phyllachora species on myrtaceous hosts from the Brazilian Cerrado was also included.