Molecular Mechanism Of Recessive Self-compatibility In Brassica Napus And Functional Analysis Of Atpub2in Self-Incompatibility Response

Self-incompatibility is a special reproduction barrier and adopted by many flowering plants in evolution. The self-incompatible ligand-receptor specific recognition, intracellular signal transduction and the evolution from cross-pollination to self-pollination were studied as a classic example in botany research. As an efficient pollination control system, self-incompatibility can be applied in cruciferae heterosis utilization. The maintainers can be used to breed self-incompatible lines because the F1are still self-incomatible when they crossed with self-incompatible line S-1300(Brassica napus). But the genetic mechanism is not clear. BnARC1is a U-box protein with E3ubiquitin ligase activity, mediated self-incompatibility signal transduction response in Brassica. Whether there is a functional ortholog of BnARCl that assumed the role of BnARC1in self-incompatible pollination response in Arabidopsis thaliana still need to be confirmed.This study consists of two parts of work. The first part is molecular mechanism of recessive self-compatibility in Brassica napus. The second part is functional analysis of AtPUB2in self-incompatible pollination response in A. thaliana. The main results are outlined as follows:1. Screening and identification of self-incompatibility maintainers in B. napus12core maintainers of self-incompatible line S-1300were screened. The S haplotype analysis showed that the S haplotypes were derived from BrS-29on A genome and BoS-15on C genome in all maintainers.2. Genetic analysis of recessive self-compatibility in B. napusAnalysis of S locus genotypes and phenotypes in S-1300X maintainers segregation populations revealed that the recessive self-compatibility of Bing409was controlled by a single locus. The phenotype was decided by A genome S locus genotype. And the self-incompatibility of S-1300is dominant to Bing409. The recessive self-compatibility of89008was not controlled by a single locus. There must be other genes besides S locus control the SI phenotype.3. Analysis of recessive self-incompatibility mechanism in Brassica napusAccording to the expressing result of S locus genes, analysis of recessive self- compatibility molecular mechanism was performed. The maintainers were self-compatible. Because the specific recognition was inhibited when the SP11gene was not expressed, or there must be some other genes besides S locus affect the SI response when the SP111gene expression was normal. The F1from S-1300×maintainers were self-incompatible. Because the BrSP11-29ortholog was not expressed but the functional BrSP11-60ortholog expression was normal.4. Functional analysis of AtPUB2in self-incompatible pollination response in A. thalianaThe self-incompatibility response was neither abolished nor weakened by knocking out of AtPUB2. The AtPUB2ARM-repeats domain was not interacting with the SRKb kinase domain. AtPUB2was predominantly expressed in the cells of ground tissue and vasculature below the stigma epidermis but not in the sigma papilla cells. AtPUB2is not a functional ortholog of BnARCl and is not involved in SI response.