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Design of an F1 hybrid breeding strategy for ryegrasses based on selection of self-incompatibility locus-specific alleles.

Pembleton LW, Shinozuka H, Wang J, Spangenberg GC, Forster JW, Cogan NO - Front Plant Sci (2015)

Bottom Line: This property is partially due to an inability to effectively exploit heterosis through the formation of F1 hybrids.Based on simulation of various levels of SI allele diversity restriction, the most effective scheme will generate 83.33% F1 hybrids.Results from the study, including the impact of varying flowering time, are discussed along with a proposed breeding design for commercial application.

View Article: PubMed Central - PubMed

Affiliation: Biosciences Research Division, AgriBio, La Trobe University Bundoora, VIC, Australia ; Dairy Futures Cooperative Research Centre, AgriBio, La Trobe University Bundoora, VIC, Australia ; School of Applied Systems Biology, La Trobe University Bundoora, VIC, Australia.

ABSTRACT
Relatively modest levels of genetic gain have been achieved in conventional ryegrass breeding when compared to cereal crops such as maize, current estimates indicating an annual improvement of 0.25-0.6% in dry matter production. This property is partially due to an inability to effectively exploit heterosis through the formation of F1 hybrids. Controlled crossing of ryegrass lines from geographically distant origins has demonstrated the occurrence of heterosis, which can result in increases of dry matter production in the order of 25%. Although capture of hybrid vigor offers obvious advantages for ryegrass cultivar production, to date there have been no effective and commercially suitable methods for obtaining high proportions of F1 hybrid seed. Continued advances in fine-scale genetic and physical mapping of the gametophytic self-incompatibility (SI) loci (S and Z) of ryegrasses are likely in the near future to permit the identification of closely linked genetic markers that define locus-specific haplotypes, allowing prediction of allelic variants and hence compatibility between different plant genotypes. Given the availability of such information, a strategy for efficient generation of ryegrass cultivars with a high proportion of F1 hybrid individuals has been simulated, which is suitable for commercial implementation. Through development of two parental pools with restricted diversity at the SI loci, relative crossing compatibility between pools is increased. Based on simulation of various levels of SI allele diversity restriction, the most effective scheme will generate 83.33% F1 hybrids. Results from the study, including the impact of varying flowering time, are discussed along with a proposed breeding design for commercial application.

No MeSH data available.


Strategy for F1 hybrid production based on Se1.
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Figure 3: Strategy for F1 hybrid production based on Se1.

Mentions: After formation of the parental pools in Se1, and subsequent cycles of within-pool mating (for seed multiplication), seed from both pools can be mixed equally as a 1:1 blend and the derived mature plants be allowed to inter-pollinate randomly in a field setting (Figure 3). The 50% of individuals within each pool that are heterozygous at both S and Z, and therefore incompatible within the pool, will solely be fertilized by pollen from the other parental pool, yielding 100% F1 hybrid seed. Although the remaining individuals will not produce 100% hybrid seed, they are only partially compatible within the pool (Figure 2), and so will produce a higher proportion of hybrid than non-hybrid seed. This is a consequence of 100% compatibility for the pollen-specific alleles from the opposing pool, as compared to 66.67% within the pool, hence leading to out-competition of the within-pool-derived pollen alleles. As validated through simulation, this effect will on average obtain 83.33% of seed generated from the inter-mating pools as F1 hybrid in nature.


Design of an F1 hybrid breeding strategy for ryegrasses based on selection of self-incompatibility locus-specific alleles.

Pembleton LW, Shinozuka H, Wang J, Spangenberg GC, Forster JW, Cogan NO - Front Plant Sci (2015)

Strategy for F1 hybrid production based on Se1.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585157&req=5

Figure 3: Strategy for F1 hybrid production based on Se1.
Mentions: After formation of the parental pools in Se1, and subsequent cycles of within-pool mating (for seed multiplication), seed from both pools can be mixed equally as a 1:1 blend and the derived mature plants be allowed to inter-pollinate randomly in a field setting (Figure 3). The 50% of individuals within each pool that are heterozygous at both S and Z, and therefore incompatible within the pool, will solely be fertilized by pollen from the other parental pool, yielding 100% F1 hybrid seed. Although the remaining individuals will not produce 100% hybrid seed, they are only partially compatible within the pool (Figure 2), and so will produce a higher proportion of hybrid than non-hybrid seed. This is a consequence of 100% compatibility for the pollen-specific alleles from the opposing pool, as compared to 66.67% within the pool, hence leading to out-competition of the within-pool-derived pollen alleles. As validated through simulation, this effect will on average obtain 83.33% of seed generated from the inter-mating pools as F1 hybrid in nature.

Bottom Line: This property is partially due to an inability to effectively exploit heterosis through the formation of F1 hybrids.Based on simulation of various levels of SI allele diversity restriction, the most effective scheme will generate 83.33% F1 hybrids.Results from the study, including the impact of varying flowering time, are discussed along with a proposed breeding design for commercial application.

View Article: PubMed Central - PubMed

Affiliation: Biosciences Research Division, AgriBio, La Trobe University Bundoora, VIC, Australia ; Dairy Futures Cooperative Research Centre, AgriBio, La Trobe University Bundoora, VIC, Australia ; School of Applied Systems Biology, La Trobe University Bundoora, VIC, Australia.

ABSTRACT
Relatively modest levels of genetic gain have been achieved in conventional ryegrass breeding when compared to cereal crops such as maize, current estimates indicating an annual improvement of 0.25-0.6% in dry matter production. This property is partially due to an inability to effectively exploit heterosis through the formation of F1 hybrids. Controlled crossing of ryegrass lines from geographically distant origins has demonstrated the occurrence of heterosis, which can result in increases of dry matter production in the order of 25%. Although capture of hybrid vigor offers obvious advantages for ryegrass cultivar production, to date there have been no effective and commercially suitable methods for obtaining high proportions of F1 hybrid seed. Continued advances in fine-scale genetic and physical mapping of the gametophytic self-incompatibility (SI) loci (S and Z) of ryegrasses are likely in the near future to permit the identification of closely linked genetic markers that define locus-specific haplotypes, allowing prediction of allelic variants and hence compatibility between different plant genotypes. Given the availability of such information, a strategy for efficient generation of ryegrass cultivars with a high proportion of F1 hybrid individuals has been simulated, which is suitable for commercial implementation. Through development of two parental pools with restricted diversity at the SI loci, relative crossing compatibility between pools is increased. Based on simulation of various levels of SI allele diversity restriction, the most effective scheme will generate 83.33% F1 hybrids. Results from the study, including the impact of varying flowering time, are discussed along with a proposed breeding design for commercial application.

No MeSH data available.