Cross-incompatibility and self-incompatibility: unrelated phenomena in wild and cultivated potatoes?

Abstract

Knowledge of internal hybridization barriers is relevant for germplasm conservation and utilization. The two pre-zygotic barriers are pollen–pistil self-incompatibility (SI) and cross-incompatibility (CI). To ascertain whether SI and CI were phenotypically related phenomena in potatoes, extensive intra- and interspecific, both intra- and interploidy breeding relationships were established, without previous assumptions on the compatibility behavior of the studied germplasm. Pollen–pistil relationships were analyzed at the individual genotype/accession/family level. In two seasons, 828 intra- and interspecific genotypic combinations were performed, using accessions of the wild potatoes Solanum chacoense Bitter (2n = 2x = 24), S. gourlayi Hawkes (2n = 2x = 24; 2n = 4x = 48), and S. spegazzinii Bitter (2n = 2x = 24), full-sibling (hereinafter “full-sib”) families (2n = 2x = 24) within/between the latter two diploids, and S. tuberosum L. (2n = 4x = 48) cultivars. Pollen–pistil incompatibility occurred in the upper first third of the style (I1/3) in all selfed diploids. In both the intra- and interspecific combinations, the most frequent relationship was compatibility, followed by I1/3, but incompatibility also occurred in the stigma and the style (middle third and bottom third). We observed segregation for these relationships in full-sib families, and unilateral and bilateral incompatibility in reciprocal crosses between functional SI genotypes. Cross-incompatibility in potatoes is, apparently, controlled by genes independent of the S-locus or its S-haplotype recognition region (although molecular evidence is needed to confirm it), with segregation even within accessions.

Pollination Type Recognition from a Distance by the Ovary Is Revealed Through a Global Transcriptomic Analysis

“…Since gametophytic SI is an important PT rejection mechanism in our model species, involving pollination-induced regulation of pistil transcripts [52,53,54], we chose to compare the effect of CCP and CIP on gene expression in the ovary. Moreover, the existence of cross-incompatibility barriers affecting pollen–pistil interactions in wild potatoes [55] led us to include a HCP condition in our study. To minimize incongruity problems, we chose to perform HCP with pollen from a closely related self-incompatible species, S. microdontum , which was previously shown to make fertile hybrids with S. chacoense [56].…”

Evolution of interspecies unilateral incompatibility in the relatives of Arabidopsis thaliana

“…Analyses of the genetic structures of interspecies UI, in particular SI × SI type UI, have been greatly hampered by difficulties to obtain interspecies hybrids and generate populations for subsequent genetic analyses. Although SI × SI, SI × SC and SC × SC type interspecies UI has all been identified in Solanum species (Baek et al., ; Covey et al., ; Maune, Camadro, & Erazzú, ; Qin et al., ; Tovar‐Mendez et al., ), genetic structures have only been investigated in SI × SC (Li & Chetelat, ; Li, Royer, & Chetelat, ; Murfett et al., ) and SC × SC (Qin et al., ; Tovar‐Mendez et al., ) type UI. In Brassica species, only SI × SC type UI was genetically studied (Udagawa et al., ).…”

Comparative floral ecology and breeding systems between sympatric populations of <i>Nothoscordum bivalve</i> and <i>Allium stellatum</i> (Amaryllidaceae)

“…Therefore, our results suggest that N. bivalve expresses outbreeding depression as a product of intraspecific crossincompatibility, a rare and understudied breeding system. This is not to be confused with interspecific cross-incompatibility (Maune et al 2017) or even obligate autogamy (sensu Ornduff 1969).…”