New insights into the hybrid origin of Malus toringoides and its close relatives based on a single-copy nuclear gene SbeI and three chloroplast fragments

Malus toringoides Hughes and its close relatives, M. maerkangensis M. H. Cheng et al., M. setok Vassilcz., and M. xiaojinensis M. H. Cheng & N. G. Jiang were supposed to derive from hybridizations. However, molecular data are still inadequate to corroborate the hybrid origin hypotheses. In this...

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Published in:Journal of systematics and evolution : JSE 2014-07, Vol.52 (4), p.477-486
Main Authors: TANG, Liang, LI, Ju, TAN, Si, LI, Ming‐Xia, MA, Xiang, ZHOU, Zhi‐Qin
Format: Article
Language:English
Subjects:
Chloroplasts
close
close relatives
Evolution
gene
genes
hybrid origin
hybridization
hybrids
Malus
Malus toringoides
nuclear
origin
hybridization
Malus
parents
phylogeny
relatives
hybrid
single-copy nuclear gene
Studies
toringoides
single-copy
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Summary:Malus toringoides Hughes and its close relatives, M. maerkangensis M. H. Cheng et al., M. setok Vassilcz., and M. xiaojinensis M. H. Cheng & N. G. Jiang were supposed to derive from hybridizations. However, molecular data are still inadequate to corroborate the hybrid origin hypotheses. In this study, we sequenced a single‐copy nuclear gene SbeI and three chloroplast fragments and carried out phylogenetic analyses to investigate the evolutionary origins of the above four putative hybrid taxa. The hybrid nature of M. toringoides is confirmed by the detection of two distinct types of SbeI sequences from it. The chloroplast and SbeI gene phylogenies show that the maternal progenitor of M. toringoides is closely related to M. sikkimensis N. P. Balakr. and M. spectabilis Borkh., and the paternal progenitor is most likely M. transitoria C. K. Schneid. The hypothesis that M. kansuensis (Batalin) C. K. Schneid. is one of the parents of M. toringoides is not supported. Malus maerkangensis and M. xiaojinensis might have originated through hybridization between M. toringoides and M. kansuensis, whereas M. setok is genetically closely related to M. toringoides. The three close relatives of M. toringoides were designated as three novel species by some researchers, however, as they were all apomictic with limited distribution areas and they originated from hybridization and polyploidization, we recommend that their species status should be re‐evaluated.
ISSN:1674-4918
1759-6831
DOI:10.1111/jse.12079