Speciation by triparental hybridization in genus Sorbus (Rosaceae)

Abstract

Hybridization associated with polyploidization and apomixis is a frequent mechanism of speciation. Sorbus is a genus with ongoing hybridization resulting in a polyploid complex with different parental lineage. Triparens is the smallest hybridogenous subgenus of Sorbus so far known to comprise only two taxa, S. intermedia and S. × liljeforsii that combine the genomes of three taxa (S. aria agg., S. aucuparia and S. torminalis). To elucidate the origins of S. dacica, S. paxiana and S. tauricola, three new trigenomic candidates formerly believed to be of biparental origin with either S. aria agg. × S. aucuparia or S. aria agg. × S. torminalis lineage we combined data from HPLC and chloroplast DNA analysing additional 33 related taxa as well. We concluded that the ‘torminalis-type’ flavonoid profile and the ‘aucuparia-type’ plastid indicate the participation of both S. torminalis and S. aucuparia resulting in the formation of S. dacica, S. paxiana and S. tauricola. Sorbus aria agg. as the third ancestor and as a necessary link to meet genes of S. torminalis and S. aucuparia in one genome is obvious from morphological features (densely tomentose undersides of leaves). The tetraploid cytotypes and obligate pseudogamy of S. dacica and S. paxiana were determined by flow cytometry and are published here for the first time. The most probable evolutionary scenario for Triparens species is: 1. a diploid sexual S. aucuparia as pollen acceptor hybridized with a tetraploid apomictic taxon from the S. aria agg. producing a triploid apomictic taxon with ‘aucuparia-type’ plastid inherited maternally; 2. during a second crossing event this subgenus Soraria hybrid as maternal progenitor hybridized with the sexual diploid S. torminalis (providing gene(s) of apigenin O-glucuronide synthesis) forming a tetraploid Triparens hybrid with ‘aucuparia-type’ plastid and ‘torminalis-type’ flavonoids.

Phytoprofiling of Sorbus L. Inflorescences: A Valuable and Promising Resource for Phenolics

“…The genus Sorbus L. has a highly complicated systematics encompassing numerous subgenera and sections that determine its diversity sensu lato [7]. Furthermore, Sorbus' extraordinary apomixis, cross-breeding, and intergeneric hybridization abilities have led to a great expansion of Sorbus genotypes, cultivars, hybrids, and varieties [8,9]. Almost all parts of the Sorbus plants have a historical record of usage in various traditional medicinal systems, as well as in food, fodder, beauty, health, and wellness-promoting products [10][11][12][13][14].…”

Phylogeny ofCrataegus(Rosaceae) based on 257 nuclear loci and chloroplast genomes: evaluating the impact of hybridization

“…The relative importance of hybridization in the evolution of Crataegus L. (and in some other Rosaceae) has been contentious in the past, and is reviewed elsewhere ( Dickinson, 2018 ); it suffices for now to note that just within subtribe Malinae (fleshy fruits derived from hypanthial, or inferior, ovaries; Rosaceae subfamily Amygdaloideae) there are molecular data to document hybridization in several large genera ( Burgess et al, 2015 ; Cushman et al, 2017 ; Hamston et al, 2018 ; Li et al, 2014 ; Li et al, 2017 ; Liu et al, 2020 ; Németh et al, 2020 ), including Crataegus . This genus of approximately 200 or more species ( Phipps, 2015 ) is found in a small clade of five genera and ca.…”

Pollen Morphology in Sorbus L. (Rosaceae) and Its Taxonomic Implications

“…In our cluster analysis, these three subgenera were grouped together (Group C). Previous studies have shown that S. intermedia contains apigenin O-glucuronide, which reflects its close affinity to S. torminalis [ 4 , 45 ]. The cluster phenogram also indicates that S. intermedia and S. torminalis share the same branch, indicating a closely related pollen morphology between the two species.…”

“…The East Asia region is considered the center of distribution for Sorbus . Due to factors such as intraspecific variation, polyploidy, and interspecific hybridization, species circumscription within this genus is highly challenging [ 1 , 3 , 4 ]. Initially, Linnaeus only included two compound-leaved species when he first published about this genus [ 5 ].…”