Articles
2N GAMETE FORMATION IN CITRUS SINENSIS (L.) OSBECK: GENOTYPES, MECHANISMS, AND RELATED GENE HOMOLOGUES
Article number
892_4
Pages
43 – 48
Language
English
Abstract
Seedless citrus triploid progeny have been frequently produced from sexual hybridization between some diploid parents, which result from spontaneous 2n gametes.
We previously reported that only Citrus sinensis (sweet orange) × Poncirus trifoliate (trifoliate orange), not the reciprocal crosses, could produce triploid hybrids in which the extra haploid genome was from only the maternal sweet orange (2n eggs), according to EST-SSR markers.
Therefore, the related genes or genomic mechanism likely existed only in sweet orange, not in trifoliate orange, and 2n eggs might form during first division restitution (FDR) based on the 2n egg genotypes and ratios at heterozygous loci in sweet orange.
In Arabidopsis and other plants, several meiotic mutant genes related to 2n gamete formation have been isolated and characterized.
Using these known gene sequences, we have identified their homologues in citrus.
Sequence comparison shown the homologues in citrus shared high similarity to the known genes in deduced amino acids and domain structures, suggesting they may have similar functions.
By comparison of sweet orange, trifoliate orange, their triploids and normal diploids, genotypic polymorphisms and expressed differences were also found among some homologous genes.
Further functional analysis of these homologues will lead to the isolation of the gene(s) controlling the 2n egg formation and utilization in seedlessness breeding in Citrus sinensis.
We previously reported that only Citrus sinensis (sweet orange) × Poncirus trifoliate (trifoliate orange), not the reciprocal crosses, could produce triploid hybrids in which the extra haploid genome was from only the maternal sweet orange (2n eggs), according to EST-SSR markers.
Therefore, the related genes or genomic mechanism likely existed only in sweet orange, not in trifoliate orange, and 2n eggs might form during first division restitution (FDR) based on the 2n egg genotypes and ratios at heterozygous loci in sweet orange.
In Arabidopsis and other plants, several meiotic mutant genes related to 2n gamete formation have been isolated and characterized.
Using these known gene sequences, we have identified their homologues in citrus.
Sequence comparison shown the homologues in citrus shared high similarity to the known genes in deduced amino acids and domain structures, suggesting they may have similar functions.
By comparison of sweet orange, trifoliate orange, their triploids and normal diploids, genotypic polymorphisms and expressed differences were also found among some homologous genes.
Further functional analysis of these homologues will lead to the isolation of the gene(s) controlling the 2n egg formation and utilization in seedlessness breeding in Citrus sinensis.
Authors
Chunxian Chen, F.G. Gmitter Jr.
Keywords
spontaneous polyploidy, comparative genomics, seedless
Online Articles (48)