Natural variation in potato sexual reproduction facilitates breeding

Abstract

The origin and widespread occurrence of Sli based self-compatibility in potato Chapter 3 46 High-density linkage map constructed from a skim sequenced diploid potato population reveals transmission distortion and QTLs for tuber yield and pollen shed Chapter 4 74Desynapsis in potato is caused by StMSH4 mutant alleles and leads to either highly uniform unreduced pollen or sterility Chapter 5 94Identification of two mutant JASON-RELATED genes associated with unreduced pollen production in potato Chapter 6 122 General discussion References 143Summary 167Acknowledgements 171 About the author 179Education statement recognition model (Kubo et al., 2010), the combined action of the SLFs encoded by one S-haplotype results in the recognition and degradation of all S-RNases except of the one encoded by their own haplotype. Hence, self-incompatibility occurs when the Shaplotype of the pollen matches either of the two S-haplotypes of the style. This elegant model also provides an explanation for the phenomenon of competitive interaction that allows tetraploid potatoes to become self-compatible (Olsder and Hermsen, 1976). When tetraploid clones produce diploid heteroallelic pollen that expresses two complementary sets of S-locus F-box proteins (SLFs), all S-RNases are ubiquitinated, which breaks down gametophytic self-incompatibility.Recently, self-compatible diploid potato clones were engineered by a knock-out of the gene encoding for the S-RNase (Enciso-Rodriguez et al., 2019;Ye et al., 2018). Furthermore, a self-compatible diploid clone bearing a naturally weakly expressed S-RNase was recently identified . Other cases of self-compatibility among S. tuberosum dihaploids were reported in earlier studies (De Jong and Rowe, 1971;Olsder and Hermsen, 1976), but the genetic and mechanistic basis of their selfcompatibility remained undetermined prior to this thesis. Despite those alternative options, the most widely used source of self-compatibility is the dominant gene Sli originally identified from a S. chacoense accession and located on chromosome 12 Hanneman, 1998a, 1998b). The causal gene behind Sli was recently shown to encode for a pollen-expressed F-box protein functioning as a general S-RNase inhibitor (Eggers et al., 2021;Ma et al., 2021).