Crossability barriers in Prunus: the role of modifiers in the regulation of the gametophytic self-incompatibility system
[EN] Self-incompatibility (SI) comprises a compendium of molecular intraspecific barriers, controlled by the S-locus, which enhances outcrossing and prevents inbreeding. Solanaceae, Plantaginaceae and Rosaceae exhibit the Gametophytic SI (GSI) type where specific recognition is controlled by S-RNase...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | inglés |
| OAI Identifier: | oai:riunet.upv.es:10251/68489 |
| Acceso en línea: | https://riunet.upv.es/handle/10251/68489 |
| Access Level: | acceso abierto |
| Palabra clave: | Self-Incompatibility Prunus Modifiers Pollen-Part Mutation |
| Sumario: | [EN] Self-incompatibility (SI) comprises a compendium of molecular intraspecific barriers, controlled by the S-locus, which enhances outcrossing and prevents inbreeding. Solanaceae, Plantaginaceae and Rosaceae exhibit the Gametophytic SI (GSI) type where specific recognition is controlled by S-RNases and S-locus F-box (SFB) proteins as the female and male S-determinants, respectively. On the other hand, unlinked S-locus genes known as modifier factors are also completely necessary for the mechanism to function. The GSI system seems to be basically preserved in Prunus but striking differences with Solanaceae and other Rosaceae have also been observed. On the basis of this background, this thesis is focused on the identification and characterization of modifiers involved in Prunus GSI to improve our understanding of the underlying mechanism. Previous works in apricot showed that an S-locus unlinked mutation expressed in pollen and located at the distal end of chr. 3 (M-locus) confers self-compatibility in the cv. 'Canino'. In this work, another self-compatible apricot cultivar, named 'Katy', was molecular and genetically analyzed. Similarly, an S-locus unlinked pollen-part mutation was found to cause the loss of self-incompatible response. A mapping strategy based on segregation distorted loci mapped 'Katy' mutation (referred as m-mutation) at the distal end of chr. 3, in a region overlapping with that identified for 'Canino' M-locus. A new screening was carried out to identify additional self-compatible mutants in apricot cultivar/accessions from germplasm banks. Through S-genotyping, three uncategorized S-alleles were recovered and two new mutations putatively conferring self-compatibility (SC) by affecting the male S-determinant SFB were detected. Additionally, M-genotyping showed that the same mutated m-haplotype was shared by 'Canino' and 'Katy', but also by 17 cultivars more from North-America and Western-Europe. A widely distributed haplotype M1-0 was proposed as the putative m-haplotype ancestor suggesting that it arose much later in time than SC-allele, a mutation in the S-locus also conferring SC in apricot. In order to identify this mutation, an integrative genetic, genomic and transcriptomic approach based on NGS data from 'Canino', 'Katy' and the self-incompatible apricot cultivar 'Goldrich' was carried out. This approach led to identify a unique polymorphism able to explain the self-compatible phenotype, a FaSt insertion type of 358-bp in coupling with the m-haplotype within a gene encoding a disulfide bond A-like oxidoreductase (named PaMDOr). PaMDOr was found to be differentially over expressed in mature anthers and the FaSt insertion is predicted to produce a truncated protein. These two findings also support PaMDOr as the pollen-part mutated modifier conferring SC in apricot. Furthermore, phylogenetic analyses suggest PaMDOr as a putative paralog of its contiguous gene (PaM-8), that emerged after the split of the Rosaceae and Solanaceae and which function became essential for the proper functioning of the GSI system in Prunus. Aimed to shed light on the differences and similarities between the S-RNase-based GSI systems in Rosaceae and Solanaceae, orthology relationships were analyzed for modifiers. Putative orthologs were found for NaTrxh, SBP1 and MdABCF in Prunus but a more complex evolutionary pattern was detected for 120K, NaStEP and NaPCCP. Thus, in spite of the differences, it can be hypothesized that part of the GSI modifier factors are shared by both families. As a whole, the multidisciplinary strategy developed in this thesis has allowed us to identify a novel modifier factor (PaMDOr) essential for the self-incompatible response in Prunus as the most significant contribution. In addition, new sources of SC have been detected in apricot and the orthology analysis helped to deepen our understanding on evolutionary aspects of the S-RNase-based GSI system exhibited by Prunus. |
|---|