BACKGROUND AND AIMS: Polyploidy is a major component of plant evolution. The citrus gene pool is essentially diploid but tetraploid plants are frequently encountered in seedlings of diploid apomictic genotypes. The main objectives of the present study were to establish the origin of these tetraploid plants and to ascertain the importance of genotypic and environmental factors on tetraploid formation. METHODS: Tetraploid seedlings from 30 diploid apomictic genotypes were selected by flow cytometry and genotyped with 24 single sequence repeat (SSR) markers to analyse their genetic origin. Embryo rescue was used to grow all embryos contained in polyembryonic seeds of 'Tardivo di Ciaculli' mandarin, followed by characterization of the plantlets obtained by flow cytometry and SSR markers to accurately establish the rate of tetraploidization events and their potential tissue location. Inter-annual variations in tetraploid seedling rates were analysed for seven genotypes. Variation in tetraploid plantlet rates was analysed between different seedlings of the same genotype ('Carrizo' citrange; Citrus sinensis × Poncirus trifoliata) from seeds collected in different tropical, subtropical and Mediterranean countries. KEY RESULTS: Tetraploid plants were obtained for all the studied diploid genotypes, except for four mandarins. All tetraploid plants were identical to their diploid maternal line for SSR markers and were not cytochimeric. Significant genotypic and environmental effects were observed, as well as negative correlation between mean temperature during the flowering period and tetraploidy seedling rates. The higher frequencies (20 %) of tetraploids were observed for citranges cultivated in the Mediterranean area. CONCLUSIONS: Tetraploidization by chromosome doubling of nucellar cells are frequent events in apomictic citrus, and are affected by both genotypic and environmental factors. Colder conditions in marginal climatic areas appear to favour the expression of tetraploidization. Tetraploid genotypes arising from chromosome doubling of apomictic citrus are extensively being used as parents in breeding programmes to develop seedless triploid cultivars and have potential direct use as new rootstocks.
BACKGROUND AND AIMS: Polyploidy is a major component of plant evolution. The citrus gene pool is essentially diploid but tetraploid plants are frequently encountered in seedlings of diploid apomictic genotypes. The main objectives of the present study were to establish the origin of these tetraploid plants and to ascertain the importance of genotypic and environmental factors on tetraploid formation. METHODS: Tetraploid seedlings from 30 diploid apomictic genotypes were selected by flow cytometry and genotyped with 24 single sequence repeat (SSR) markers to analyse their genetic origin. Embryo rescue was used to grow all embryos contained in polyembryonic seeds of 'Tardivo di Ciaculli' mandarin, followed by characterization of the plantlets obtained by flow cytometry and SSR markers to accurately establish the rate of tetraploidization events and their potential tissue location. Inter-annual variations in tetraploid seedling rates were analysed for seven genotypes. Variation in tetraploid plantlet rates was analysed between different seedlings of the same genotype ('Carrizo' citrange; Citrus sinensis × Poncirus trifoliata) from seeds collected in different tropical, subtropical and Mediterranean countries. KEY RESULTS: Tetraploid plants were obtained for all the studied diploid genotypes, except for four mandarins. All tetraploid plants were identical to their diploid maternal line for SSR markers and were not cytochimeric. Significant genotypic and environmental effects were observed, as well as negative correlation between mean temperature during the flowering period and tetraploidy seedling rates. The higher frequencies (20 %) of tetraploids were observed for citranges cultivated in the Mediterranean area. CONCLUSIONS: Tetraploidization by chromosome doubling of nucellar cells are frequent events in apomictic citrus, and are affected by both genotypic and environmental factors. Colder conditions in marginal climatic areas appear to favour the expression of tetraploidization. Tetraploid genotypes arising from chromosome doubling of apomictic citrus are extensively being used as parents in breeding programmes to develop seedless triploid cultivars and have potential direct use as new rootstocks.
Authors: Robert M Stupar; Pudota B Bhaskar; Brian S Yandell; Willem A Rensink; Amy L Hart; Shu Ouyang; Richard E Veilleux; James S Busse; Robert J Erhardt; C Robin Buell; Jiming Jiang Journal: Genetics Date: 2007-06-11 Impact factor: 4.562
Authors: Jianlin Wang; Lu Tian; Hyeon-Se Lee; Ning E Wei; Hongmei Jiang; Brian Watson; Andreas Madlung; Thomas C Osborn; R W Doerge; Luca Comai; Z Jeffrey Chen Journal: Genetics Date: 2005-09-19 Impact factor: 4.562
Authors: Franck Curk; Frédérique Ollitrault; Andres Garcia-Lor; François Luro; Luis Navarro; Patrick Ollitrault Journal: Ann Bot Date: 2016-03-04 Impact factor: 4.357
Authors: Patrick Ollitrault; Javier Terol; Chunxian Chen; Claire T Federici; Samia Lotfy; Isabelle Hippolyte; Frédérique Ollitrault; Aurélie Bérard; Aurélie Chauveau; Jose Cuenca; Gilles Costantino; Yildiz Kacar; Lisa Mu; Andres Garcia-Lor; Yann Froelicher; Pablo Aleza; Anne Boland; Claire Billot; Luis Navarro; François Luro; Mikeal L Roose; Frederick G Gmitter; Manuel Talon; Dominique Brunel Journal: BMC Genomics Date: 2012-11-05 Impact factor: 3.969