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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.


Average year 7 TCA of trees in each genotypic class. The number of individuals in each class is given in parentheses; error bars indicate standard error. Average TCAs were compared to the group with neither Dw1 nor Dw2 by ANOVA; asterisks indicate the means are significantly different with a P value of <0.001. Data are from 303 trees from the second population.
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fig4: Average year 7 TCA of trees in each genotypic class. The number of individuals in each class is given in parentheses; error bars indicate standard error. Average TCAs were compared to the group with neither Dw1 nor Dw2 by ANOVA; asterisks indicate the means are significantly different with a P value of <0.001. Data are from 303 trees from the second population.

Mentions: After 7 years of growth, the TCA of 303 trees from the second population were measured. Trees grafted onto rootstocks carrying both Dw1 and Dw2 exhibited the lowest average TCA, only 23% of that of scions on rootstocks with neither loci. Rootstocks with Dw1 alone reduced scion TCA to 73% of those with neither rootstock loci. Surprisingly, trees grafted onto rootstocks with Dw2 alone had the highest TCA of all (Figure 4).


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)

Average year 7 TCA of trees in each genotypic class. The number of individuals in each class is given in parentheses; error bars indicate standard error. Average TCAs were compared to the group with neither Dw1 nor Dw2 by ANOVA; asterisks indicate the means are significantly different with a P value of <0.001. Data are from 303 trees from the second population.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig4: Average year 7 TCA of trees in each genotypic class. The number of individuals in each class is given in parentheses; error bars indicate standard error. Average TCAs were compared to the group with neither Dw1 nor Dw2 by ANOVA; asterisks indicate the means are significantly different with a P value of <0.001. Data are from 303 trees from the second population.
Mentions: After 7 years of growth, the TCA of 303 trees from the second population were measured. Trees grafted onto rootstocks carrying both Dw1 and Dw2 exhibited the lowest average TCA, only 23% of that of scions on rootstocks with neither loci. Rootstocks with Dw1 alone reduced scion TCA to 73% of those with neither rootstock loci. Surprisingly, trees grafted onto rootstocks with Dw2 alone had the highest TCA of all (Figure 4).

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.