Sandra Bretones

Pollen development is a crucial biological process indispensable for seed set in flowering plants and for successful crop breeding. However, little is known about the molecular mechanisms regulating pollen development in crop species. This study reports a novel male-sterile tomato mutant, pollen deficient 2 (pod2), characterized by the production of non-viable pollen grains and resulting in the development of small parthenocarpic fruits. A combined strategy of mapping-by-sequencing and RNA interference-mediated gene silencing was used to prove that the pod2 phenotype is caused by the loss of Solanum lycopersicum G-type lectin receptor kinase II.9 (SlG-LecRK-II.9) activity. In situ hybridization of floral buds showed that POD2/SlG-LecRK-II.9 is specifically expressed in tapetal cells and microspores at the late tetrad stage. Accordingly, abnormalities in meiosis and tapetum programmed cell death in pod2 occurred during microsporogenesis, resulting in the formation of four dysfunction...

Tomato (Solanum lycopersicum L.) is a major horticultural crop and a model species among eudicots, especially for traits related to reproductive development. Although considerable progress has been made since the tomato genome sequence project was completed, most of the genes identified remain predictions with an unknown or hypothetical function. This lack of functional characterization hampers the use of the huge amount of genomic information available to improve the quality and productivity of this crop. Reverse genetics strategies such as artificial mutagenesis and next-generation sequencing approaches build the perfect tandem for increasing knowledge on functional annotation of tomato genes. This work reports the phenotypic characterization of a tomato mutant collection generated from an EMS chemical mutagenesis program aimed to identify interesting agronomic mutants and novel gene functions. Tomato mutants were grouped into fourteen phenotypic classes, including vegetative and ...

A dramatic evolution of fruit size has accompanied the domestication and improvement of fruit-bearing crop species. In tomato ( Solanum lycopersicum ), naturally occurring cis-regulatory mutations in the genes of the CLAVATA-WUSCHEL signaling pathway have led to a significant increase in fruit size generating enlarged meristems that lead to flowers with extra organs and bigger fruits. In this work, by combining mapping-by-sequencing and CRISPR/Cas9 genome editing methods, we isolated EXCESSIVE NUMBER OF FLORAL ORGANS ( ENO ), an AP2/ERF transcription factor which regulates floral meristem activity. Thus, the ENO gene mutation gives rise to plants that yield larger multilocular fruits due to an increased size of the floral meristem. Genetic analyses indicate that eno exhibits synergistic effects with mutations at the LOCULE NUMBER (encoding SlWUS ) and FASCIATED (encoding SlCLV3 ) loci, two central players in the evolution of fruit size in the domestication of cultivated tomatoes. Ou...

Determinacy growth habit and accelerated flowering traits were selected during or after domestication in common bean. Both processes affect several presumed adaptive traits such as the rate of plant production. There is a close association between flowering initiation and vegetative growth; however, interactions among these two crucial developmental processes and their genetic bases remain unexplored. In this study, with the aim to establish the genetic relationships between these complex processes, a multi-environment quantitative trait locus (QTL) mapping approach was performed in two recombinant inbred line populations derived from inter-gene pool crosses between determinate and indeterminate genotypes. Additive and epistatic QTLs were found to regulate flowering time, vegetative growth, and rate of plant production. Moreover, the pleiotropic patterns of the identified QTLs evidenced that regions controlling time to flowering traits, directly or indirectly, are also involved in t...

Genetic interactions of UFD gene support its specific function during reproductive development of tomato; in this process, UFD could play a pivotal role between inflorescence architecture and flower initiation genes. Tomato (Solanum lycopersicum L.) is a major vegetable crop that also constitutes a model species for the study of plant developmental processes. To gain insight into the control of flowering and floral development, a novel tomato mutant, unfinished flower development (ufd), whose inflorescence and flowers were unable to complete their normal development was characterized using double mutant and gene expression analyses. Genetic interactions of ufd with mutations affecting inflorescence fate (uniflora, jointless and single flower truss) were additive and resulted in double mutants displaying the inflorescence structure of the non-ufd parental mutant and the flower phenotype of the ufd mutant. In addition, ufd mutation promotes an earlier inflorescence meristem terminatio...