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Genetic origin and composition of a natural hybrid poplar Populus × jrtyschensis from two distantly related species.

Jiang D, Feng J, Dong M, Wu G, Mao K, Liu J - BMC Plant Biol. (2016)

Bottom Line: Two groups of cpDNA haplotypes characteristic of P. nigra and P. laurifolia respectively were both recovered for P. × jrtyschensis.Genetic structures and coalescent tests of two sets of nuclear population genetic data suggested that P. × jrtyschensis originated from hybridizations between the two assumed parental species.In the habitats of P. × jrtyschensis, there are lower concentrations of soil nitrogen than in the habitats occupied by the other two species.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China.

ABSTRACT

Background: The factors that contribute to and maintain hybrid zones between distinct species are highly variable, depending on hybrid origins, frequencies and fitness. In this study, we aimed to examine genetic origins, compositions and possible maintenance of Populus × jrtyschensis, an assumed natural hybrid between two distantly related species. This hybrid poplar occurs mainly on the floodplains along the river valleys between the overlapping distributions of the two putative parents.

Results: We collected 566 individuals from 45 typical populations of P. × jrtyschensis, P. nigra and P. laurifolia. We genotyped them based on the sequence variations of one maternally inherited chloroplast DNA (cpDNA) fragment and genetic polymorphisms at 20 SSR loci. We further sequenced eight nuclear genes for 168 individuals from 31 populations. Two groups of cpDNA haplotypes characteristic of P. nigra and P. laurifolia respectively were both recovered for P. × jrtyschensis. Genetic structures and coalescent tests of two sets of nuclear population genetic data suggested that P. × jrtyschensis originated from hybridizations between the two assumed parental species. All examined populations of P. × jrtyschensis comprise mainly F1 hybrids from interspecific hybridizations between P. nigra and P. laurifolia. In the habitats of P. × jrtyschensis, there are lower concentrations of soil nitrogen than in the habitats occupied by the other two species.

Conclusions: Our extensive examination of the genetic composition of P. × jrtyschensis suggested that it is typical of F1-dominated hybrid zones. This finding plus the low concentration of soil nitrogen in the floodplain soils support the F1-dominated bounded hybrid superiority hypothesis of hybrid zone maintenance for this particular hybrid poplar.

No MeSH data available.


Related in: MedlinePlus

Gene flow for all three species pairs. Gene flow for all three species pairs is represented by arrows. Figures beside the arrows indicate the population migration rate (Nem)
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Fig6: Gene flow for all three species pairs. Gene flow for all three species pairs is represented by arrows. Figures beside the arrows indicate the population migration rate (Nem)

Mentions: Based on SSR data sets, gene flow (Nem) was estimated to be greater from P. laurifolia and P. nigra (0.5952) than in the opposite direction (0.2218). Gene flow occurred more frequently between P. × jrtyschensis and the two parent species. More gene flow occurred from P. laurifolia to P. × jrtyschensis (2.91) than in the reverse direction (0.8644) while less was detected from P. nigra (0.8944) to P. × jrtyschensis than in the reverse direction (3.1402). The same trend was observed based on nuclear genes: gene flow was estimated to be 0.1094, 0.005 and 0.111 separately from P. laurifolia to P. nigra, from P. nigra to P. × jrtyschensis and from P. × jrtyschensis to P. laurifolia, respectively, and in the opposite direction it was estimated to be 0.0111, 0.2044 and 0.2283. In all directions, rates of gene flow estimated for the SSR data set were greater than those based on nuclear gene sequence data (Fig. 6).


Genetic origin and composition of a natural hybrid poplar Populus × jrtyschensis from two distantly related species.

Jiang D, Feng J, Dong M, Wu G, Mao K, Liu J - BMC Plant Biol. (2016)

Gene flow for all three species pairs. Gene flow for all three species pairs is represented by arrows. Figures beside the arrows indicate the population migration rate (Nem)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4836070&req=5

Fig6: Gene flow for all three species pairs. Gene flow for all three species pairs is represented by arrows. Figures beside the arrows indicate the population migration rate (Nem)
Mentions: Based on SSR data sets, gene flow (Nem) was estimated to be greater from P. laurifolia and P. nigra (0.5952) than in the opposite direction (0.2218). Gene flow occurred more frequently between P. × jrtyschensis and the two parent species. More gene flow occurred from P. laurifolia to P. × jrtyschensis (2.91) than in the reverse direction (0.8644) while less was detected from P. nigra (0.8944) to P. × jrtyschensis than in the reverse direction (3.1402). The same trend was observed based on nuclear genes: gene flow was estimated to be 0.1094, 0.005 and 0.111 separately from P. laurifolia to P. nigra, from P. nigra to P. × jrtyschensis and from P. × jrtyschensis to P. laurifolia, respectively, and in the opposite direction it was estimated to be 0.0111, 0.2044 and 0.2283. In all directions, rates of gene flow estimated for the SSR data set were greater than those based on nuclear gene sequence data (Fig. 6).

Bottom Line: Two groups of cpDNA haplotypes characteristic of P. nigra and P. laurifolia respectively were both recovered for P. × jrtyschensis.Genetic structures and coalescent tests of two sets of nuclear population genetic data suggested that P. × jrtyschensis originated from hybridizations between the two assumed parental species.In the habitats of P. × jrtyschensis, there are lower concentrations of soil nitrogen than in the habitats occupied by the other two species.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, People's Republic of China.

ABSTRACT

Background: The factors that contribute to and maintain hybrid zones between distinct species are highly variable, depending on hybrid origins, frequencies and fitness. In this study, we aimed to examine genetic origins, compositions and possible maintenance of Populus × jrtyschensis, an assumed natural hybrid between two distantly related species. This hybrid poplar occurs mainly on the floodplains along the river valleys between the overlapping distributions of the two putative parents.

Results: We collected 566 individuals from 45 typical populations of P. × jrtyschensis, P. nigra and P. laurifolia. We genotyped them based on the sequence variations of one maternally inherited chloroplast DNA (cpDNA) fragment and genetic polymorphisms at 20 SSR loci. We further sequenced eight nuclear genes for 168 individuals from 31 populations. Two groups of cpDNA haplotypes characteristic of P. nigra and P. laurifolia respectively were both recovered for P. × jrtyschensis. Genetic structures and coalescent tests of two sets of nuclear population genetic data suggested that P. × jrtyschensis originated from hybridizations between the two assumed parental species. All examined populations of P. × jrtyschensis comprise mainly F1 hybrids from interspecific hybridizations between P. nigra and P. laurifolia. In the habitats of P. × jrtyschensis, there are lower concentrations of soil nitrogen than in the habitats occupied by the other two species.

Conclusions: Our extensive examination of the genetic composition of P. × jrtyschensis suggested that it is typical of F1-dominated hybrid zones. This finding plus the low concentration of soil nitrogen in the floodplain soils support the F1-dominated bounded hybrid superiority hypothesis of hybrid zone maintenance for this particular hybrid poplar.

No MeSH data available.


Related in: MedlinePlus