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Maximum-likelihood method identifies meiotic restitution mechanism from heterozygosity transmission of centromeric loci: application in citrus.

Cuenca J, Aleza P, Juárez J, García-Lor A, Froelicher Y, Navarro L, Ollitrault P - Sci Rep (2015)

Bottom Line: Most researchers consider sexual polyploidisation leading to unreduced gamete as its main origin.Simulating data demonstrated the importance of selecting markers very close to the centromere to obtain significant conclusions at individual level.No significant conclusions were obtained for 14.1% of the hybrids.

View Article: PubMed Central - PubMed

Affiliation: Crop Protection and Biotechnology Center. Instituto Valenciano de Investigaciones Agrarias (IVIA).

ABSTRACT
Polyploidisation is a key source of diversification and speciation in plants. Most researchers consider sexual polyploidisation leading to unreduced gamete as its main origin. Unreduced gametes are useful in several crop breeding schemes. Their formation mechanism, i.e., First-Division Restitution (FDR) or Second-Division Restitution (SDR), greatly impacts the gametic and population structures and, therefore, the breeding efficiency. Previous methods to identify the underlying mechanism required the analysis of a large set of markers over large progeny. This work develops a new maximum-likelihood method to identify the unreduced gamete formation mechanism both at the population and individual levels using independent centromeric markers. Knowledge of marker-centromere distances greatly improves the statistical power of the comparison between the SDR and FDR hypotheses. Simulating data demonstrated the importance of selecting markers very close to the centromere to obtain significant conclusions at individual level. This new method was used to identify the meiotic restitution mechanism in nineteen mandarin genotypes used as female parents in triploid citrus breeding. SDR was identified for 85.3% of 543 triploid hybrids and FDR for 0.6%. No significant conclusions were obtained for 14.1% of the hybrids. At population level SDR was the predominant mechanisms for the 19 parental mandarins.

No MeSH data available.


Related in: MedlinePlus

Frequency histogram of LOD values obtained for each individual 2n gamete, indicating those arising from clementines, ‘Fortune’ mandarin and other mandarins analysed in this study.
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f5: Frequency histogram of LOD values obtained for each individual 2n gamete, indicating those arising from clementines, ‘Fortune’ mandarin and other mandarins analysed in this study.

Mentions: LOD score testing the SDR/FDR hypothesis was estimated for each individual 2n gamete from its inferred genotype, as described in the statistical method section. Positive LODs were found for 523 hybrids of the 543 analysed (Figure 5), suggesting a large global predominance of the SDR mechanism. The LOD distribution for clementine 2n gametes is displaced to higher values when compared with the distribution for ‘Fortune’ and other mandarin 2n gametes Fifty-seven diploid gametes occur with LOD between 9 and 10, and these correspond mostly to the ‘Fina’ clementine progeny (Figure 5).


Maximum-likelihood method identifies meiotic restitution mechanism from heterozygosity transmission of centromeric loci: application in citrus.

Cuenca J, Aleza P, Juárez J, García-Lor A, Froelicher Y, Navarro L, Ollitrault P - Sci Rep (2015)

Frequency histogram of LOD values obtained for each individual 2n gamete, indicating those arising from clementines, ‘Fortune’ mandarin and other mandarins analysed in this study.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403285&req=5

f5: Frequency histogram of LOD values obtained for each individual 2n gamete, indicating those arising from clementines, ‘Fortune’ mandarin and other mandarins analysed in this study.
Mentions: LOD score testing the SDR/FDR hypothesis was estimated for each individual 2n gamete from its inferred genotype, as described in the statistical method section. Positive LODs were found for 523 hybrids of the 543 analysed (Figure 5), suggesting a large global predominance of the SDR mechanism. The LOD distribution for clementine 2n gametes is displaced to higher values when compared with the distribution for ‘Fortune’ and other mandarin 2n gametes Fifty-seven diploid gametes occur with LOD between 9 and 10, and these correspond mostly to the ‘Fina’ clementine progeny (Figure 5).

Bottom Line: Most researchers consider sexual polyploidisation leading to unreduced gamete as its main origin.Simulating data demonstrated the importance of selecting markers very close to the centromere to obtain significant conclusions at individual level.No significant conclusions were obtained for 14.1% of the hybrids.

View Article: PubMed Central - PubMed

Affiliation: Crop Protection and Biotechnology Center. Instituto Valenciano de Investigaciones Agrarias (IVIA).

ABSTRACT
Polyploidisation is a key source of diversification and speciation in plants. Most researchers consider sexual polyploidisation leading to unreduced gamete as its main origin. Unreduced gametes are useful in several crop breeding schemes. Their formation mechanism, i.e., First-Division Restitution (FDR) or Second-Division Restitution (SDR), greatly impacts the gametic and population structures and, therefore, the breeding efficiency. Previous methods to identify the underlying mechanism required the analysis of a large set of markers over large progeny. This work develops a new maximum-likelihood method to identify the unreduced gamete formation mechanism both at the population and individual levels using independent centromeric markers. Knowledge of marker-centromere distances greatly improves the statistical power of the comparison between the SDR and FDR hypotheses. Simulating data demonstrated the importance of selecting markers very close to the centromere to obtain significant conclusions at individual level. This new method was used to identify the meiotic restitution mechanism in nineteen mandarin genotypes used as female parents in triploid citrus breeding. SDR was identified for 85.3% of 543 triploid hybrids and FDR for 0.6%. No significant conclusions were obtained for 14.1% of the hybrids. At population level SDR was the predominant mechanisms for the 19 parental mandarins.

No MeSH data available.


Related in: MedlinePlus