Articles
Genotyping by sequencing analysis reveals chromosome stability of different tetraploid clementines recovered by colchicine treatment, in vitro organogenesis from internodal segments and somatic cybridization
Article number
1448_6
Pages
55 – 62
Language
English
Abstract
Triploid hybrids are very promising for the selection of new seedless cultivars because they have very low gametic fertility and generally do not produce seeds nor induce seeds in other cultivars by cross-pollination.
The most efficient strategy to recover large populations of triploid hybrids is by 4x × 2x sexual hybridizations using tetraploid non-apomictic genotypes as female parents.
Tetraploid plants of non-apomictic cultivars can be produced by various methods based on in vitro shoot-tip grafting combined with treatment of the micrografted shoot-tip with colchicine or spontaneously by in vitro organogenesis from diploid internodal segments.
Somatic cybridization using electric protoplast fusion can also lead to spontaneous tetraploid plant regeneration.
The genetic analysis of citrus tetraploid plants has often been performed using a small number of molecular markers, which has hindered the study of structural variations such as large deletions or chromosome fragment duplications.
In this work, we have performed a genotyping by sequencing (GBS) analysis of 10 tetraploid plants of ‘Clemenules’, ‘Fina’ and ‘Marisol’ clementines (Citrus clementina Hort. ex Tan.) recovered by the three methods described above, as well as the three diploid parental cultivars.
After filtration for quality genotyping 9,538 SNPs were identified along the nine citrus chromosomes.
The diploid parents ‘Clemenules’, ‘Fina’ and ‘Marisol’ clementines were distinguished by these polymorphisms.
However, no significant gain or loss of large chromosome regions was observed in any of the 10 tetraploid plants analysed.
Therefore, the three tetraploidization methods appear to be more conservative of chromosome structures than symmetric protoplast fusion, for which significant chromosomal instability has been demonstrated in several allotetraploid somatic hybrids.
The most efficient strategy to recover large populations of triploid hybrids is by 4x × 2x sexual hybridizations using tetraploid non-apomictic genotypes as female parents.
Tetraploid plants of non-apomictic cultivars can be produced by various methods based on in vitro shoot-tip grafting combined with treatment of the micrografted shoot-tip with colchicine or spontaneously by in vitro organogenesis from diploid internodal segments.
Somatic cybridization using electric protoplast fusion can also lead to spontaneous tetraploid plant regeneration.
The genetic analysis of citrus tetraploid plants has often been performed using a small number of molecular markers, which has hindered the study of structural variations such as large deletions or chromosome fragment duplications.
In this work, we have performed a genotyping by sequencing (GBS) analysis of 10 tetraploid plants of ‘Clemenules’, ‘Fina’ and ‘Marisol’ clementines (Citrus clementina Hort. ex Tan.) recovered by the three methods described above, as well as the three diploid parental cultivars.
After filtration for quality genotyping 9,538 SNPs were identified along the nine citrus chromosomes.
The diploid parents ‘Clemenules’, ‘Fina’ and ‘Marisol’ clementines were distinguished by these polymorphisms.
However, no significant gain or loss of large chromosome regions was observed in any of the 10 tetraploid plants analysed.
Therefore, the three tetraploidization methods appear to be more conservative of chromosome structures than symmetric protoplast fusion, for which significant chromosomal instability has been demonstrated in several allotetraploid somatic hybrids.
Publication
Authors
P. Aleza, A. Garcia-Lor, P. Mournet, L. Navarro, P. Ollitrault
Keywords
Citrus, seedlessness, SNP markers, triploid, breeding
Groups involved
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