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Two quantitative trait loci, Dw1 and Dw2, are primarily responsible for rootstock-induced dwarfing in apple.

Foster TM, Celton JM, Chagné D, Tustin DS, Gardiner SE - Hortic Res (2015)

Bottom Line: The apple dwarfing rootstock 'Malling9' ('M9') has been used worldwide both to reduce scion vigour and as a genetic source for breeding new rootstocks.A smaller-effect QTL affecting dwarfing (Dw2) was identified on LG11, and four minor-effect QTLs were found on LG6, LG9, LG10 and LG12.Phenotypic analysis indicates that the combination of Dw1 and Dw2 has the strongest influence on rootstock-induced dwarfing, and that Dw1 has a stronger effect than Dw2.

View Article: PubMed Central - PubMed

Affiliation: The New Zealand Institute for Plant & Food Research Ltd , Palmerston North Private Bag 11600, Palmerston North 4474, New Zealand.

ABSTRACT
The apple dwarfing rootstock 'Malling9' ('M9') has been used worldwide both to reduce scion vigour and as a genetic source for breeding new rootstocks. Progeny of 'M9' segregate for rootstock-induced dwarfing of the scion, indicating that this trait is controlled by one or more genetic factors. A quantitative trait locus (QTL) analysis of a rootstock population derived from the cross between 'M9' × 'Robusta5' (non-dwarfing) and grafted with 'Braeburn' scions identified a major QTL (Dw1) on linkage group (LG) 5, which exhibits a significant influence on dwarfing of the scion. A smaller-effect QTL affecting dwarfing (Dw2) was identified on LG11, and four minor-effect QTLs were found on LG6, LG9, LG10 and LG12. Phenotypic analysis indicates that the combination of Dw1 and Dw2 has the strongest influence on rootstock-induced dwarfing, and that Dw1 has a stronger effect than Dw2. Genetic markers linked to Dw1 and Dw2 were screened over 41 rootstock accessions that confer a range of effects on scion growth. The majority of the dwarfing and semi-dwarfing rootstock accessions screened carried marker alleles linked to Dw1 and Dw2. This suggests that most apple dwarfing rootstocks have been derived from the same genetic source.

No MeSH data available.


Representation of rootstock QTLs influencing dwarfing and flowering traits on the LGs of ‘M9’ and ‘R5’. The solid part of the bars indicates the most likely position of the QTL and the lines represent the confidence interval. Traits phenotyped are listed in Table 1. The QTLs identified from ‘M9’ are in blue and located on the left side of the LGs, and the QTLs identified from ‘R5’ are in orange and located on the right side of the LGs. The markers flanking Dw1 and Dw2 are underlined and Pyrus SSR markers are indicated in red. Scale bar indicates genetic distance in cM. Details on the markers used to construct the ‘M9’ and ‘R5’ genetic maps are given in Celton et al.17 cM, centiMorgans.
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fig2: Representation of rootstock QTLs influencing dwarfing and flowering traits on the LGs of ‘M9’ and ‘R5’. The solid part of the bars indicates the most likely position of the QTL and the lines represent the confidence interval. Traits phenotyped are listed in Table 1. The QTLs identified from ‘M9’ are in blue and located on the left side of the LGs, and the QTLs identified from ‘R5’ are in orange and located on the right side of the LGs. The markers flanking Dw1 and Dw2 are underlined and Pyrus SSR markers are indicated in red. Scale bar indicates genetic distance in cM. Details on the markers used to construct the ‘M9’ and ‘R5’ genetic maps are given in Celton et al.17 cM, centiMorgans.

Mentions: The chromosome locations of QTLs identified in this study are shown in Figure 2 and Table 2. From the analysis of the first population, two QTLs from ‘M9’ were identified for control of overall dwarfing phenotype (DW%). The first one on the top of LG5 (Dw1) explained 57.2% of the phenotypic variation, and the second QTL on the top of LG11 (Dw2) explained 11.4% of the variation. From ‘R5’, QTLs affecting DW% were identified on LG10 and LG12, explaining 7.6% and 5.4% respectively of the phenotypic variation.


Two quantitative trait loci, Dw1 and Dw2, are primarily responsible for rootstock-induced dwarfing in apple.

Foster TM, Celton JM, Chagné D, Tustin DS, Gardiner SE - Hortic Res (2015)

Representation of rootstock QTLs influencing dwarfing and flowering traits on the LGs of ‘M9’ and ‘R5’. The solid part of the bars indicates the most likely position of the QTL and the lines represent the confidence interval. Traits phenotyped are listed in Table 1. The QTLs identified from ‘M9’ are in blue and located on the left side of the LGs, and the QTLs identified from ‘R5’ are in orange and located on the right side of the LGs. The markers flanking Dw1 and Dw2 are underlined and Pyrus SSR markers are indicated in red. Scale bar indicates genetic distance in cM. Details on the markers used to construct the ‘M9’ and ‘R5’ genetic maps are given in Celton et al.17 cM, centiMorgans.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4595989&req=5

fig2: Representation of rootstock QTLs influencing dwarfing and flowering traits on the LGs of ‘M9’ and ‘R5’. The solid part of the bars indicates the most likely position of the QTL and the lines represent the confidence interval. Traits phenotyped are listed in Table 1. The QTLs identified from ‘M9’ are in blue and located on the left side of the LGs, and the QTLs identified from ‘R5’ are in orange and located on the right side of the LGs. The markers flanking Dw1 and Dw2 are underlined and Pyrus SSR markers are indicated in red. Scale bar indicates genetic distance in cM. Details on the markers used to construct the ‘M9’ and ‘R5’ genetic maps are given in Celton et al.17 cM, centiMorgans.
Mentions: The chromosome locations of QTLs identified in this study are shown in Figure 2 and Table 2. From the analysis of the first population, two QTLs from ‘M9’ were identified for control of overall dwarfing phenotype (DW%). The first one on the top of LG5 (Dw1) explained 57.2% of the phenotypic variation, and the second QTL on the top of LG11 (Dw2) explained 11.4% of the variation. From ‘R5’, QTLs affecting DW% were identified on LG10 and LG12, explaining 7.6% and 5.4% respectively of the phenotypic variation.

Bottom Line: The apple dwarfing rootstock 'Malling9' ('M9') has been used worldwide both to reduce scion vigour and as a genetic source for breeding new rootstocks.A smaller-effect QTL affecting dwarfing (Dw2) was identified on LG11, and four minor-effect QTLs were found on LG6, LG9, LG10 and LG12.Phenotypic analysis indicates that the combination of Dw1 and Dw2 has the strongest influence on rootstock-induced dwarfing, and that Dw1 has a stronger effect than Dw2.

View Article: PubMed Central - PubMed

Affiliation: The New Zealand Institute for Plant & Food Research Ltd , Palmerston North Private Bag 11600, Palmerston North 4474, New Zealand.

ABSTRACT
The apple dwarfing rootstock 'Malling9' ('M9') has been used worldwide both to reduce scion vigour and as a genetic source for breeding new rootstocks. Progeny of 'M9' segregate for rootstock-induced dwarfing of the scion, indicating that this trait is controlled by one or more genetic factors. A quantitative trait locus (QTL) analysis of a rootstock population derived from the cross between 'M9' × 'Robusta5' (non-dwarfing) and grafted with 'Braeburn' scions identified a major QTL (Dw1) on linkage group (LG) 5, which exhibits a significant influence on dwarfing of the scion. A smaller-effect QTL affecting dwarfing (Dw2) was identified on LG11, and four minor-effect QTLs were found on LG6, LG9, LG10 and LG12. Phenotypic analysis indicates that the combination of Dw1 and Dw2 has the strongest influence on rootstock-induced dwarfing, and that Dw1 has a stronger effect than Dw2. Genetic markers linked to Dw1 and Dw2 were screened over 41 rootstock accessions that confer a range of effects on scion growth. The majority of the dwarfing and semi-dwarfing rootstock accessions screened carried marker alleles linked to Dw1 and Dw2. This suggests that most apple dwarfing rootstocks have been derived from the same genetic source.

No MeSH data available.