Apomixis, is an asexual mode of seed formation resulting in genetically identical or clonal seed with a maternal genotype. Apomixis has not been reported in seed crops where its flexible application in plant breeding could accelerate delivery of new varieties. By contrast, a sporophytic form of apomixis termed nucellar or adventitious embryony is common in the Rutaceae containing Citrus crop species. Here, multiple embryos develop from the maternal, somatic, nucellar cells of the ovule. They are incorporated into the enlarging embryo sac containing the sexually derived zygotic embryo and endosperm, which are products of double fertilization. Recent research has provided insights to the molecular basis for nucellar embryony. Here, we review the current understanding of the initiation, genetic basis and evolution of nucellar embryony in Citrus, and discuss prospects for future study and breeding applications of Citrus sporophytic apomixis.
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http://dx.doi.org/10.1016/j.pbi.2020.101984 | DOI Listing |
AoB Plants
July 2024
Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil.
n the Neotropics, the focus of apomictic studies predominantly centres on trees within the Brazilian savanna, characterized, mostly as sporophytic and facultative, associated with polyploidy and polyembryony. To enhance our understanding of the mechanisms governing apomixis and sexual reproduction in tropical herbaceous plants, we clarify the relationship between apomixis, chromosome counts, and polyembryony in the epiphytic orchid , which forms a polyploid complex within rocky outcrops in both the Brazilian savanna and the Atlantic forest. To define embryo origins and describe megasporogenesis and megagametogenesis, we performed manual self-pollinations in first-day flowers of cultivated plants, considering all three cytotypes (2, 3, 4) of this species.
View Article and Find Full Text PDFPlant J
August 2024
National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, Huazhong Agricultural University, Wuhan, 430070, China.
Citrus is a model plant for studying adventitious embryos, a form of asexual reproduction controlled by a single dominant gene, RWP. This gene has been identified as the causal gene for nucellar embryogenesis, but its function has not yet been fully understood. In this study, we used the fast-growing Fortunella hindsii as a system to explore chromatin accessibility during the nucellar embryony initiation, emphasizing elevated chromatin accessibility in polyembryonic (PO) genotypes compared to monoembryonic ones (MO).
View Article and Find Full Text PDFNatl Sci Rev
October 2022
Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan 430070, China.
Apomixis, or asexual seed formation, is prevalent in via a mechanism termed nucellar or adventitious embryony. Here, multiple embryos of a maternal genotype form directly from nucellar cells in the ovule and can outcompete the developing zygotic embryo as they utilize the sexually derived endosperm for growth. Whilst nucellar embryony enables the propagation of clonal plants of maternal genetic constitution, it is also a barrier to effective breeding through hybridization.
View Article and Find Full Text PDFDNA Res
September 2021
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China.
Citrus nucellar poly-embryony (NPE) is a mode of sporophytic apomixis that asexual embryos formed in the seed through adventitious embryogenesis from the somatic nucellar cells. NPE allows clonal propagation of rootstocks, but it impedes citrus cross breeding. To understand the cellular processes involved in NPE initiation, we profiled the transcriptomes and DNA methylomes in laser microdissection captured citrus apomictic cells.
View Article and Find Full Text PDFCurr Opin Plant Biol
February 2021
Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, Hubei 430070, PR China. Electronic address:
Apomixis, is an asexual mode of seed formation resulting in genetically identical or clonal seed with a maternal genotype. Apomixis has not been reported in seed crops where its flexible application in plant breeding could accelerate delivery of new varieties. By contrast, a sporophytic form of apomixis termed nucellar or adventitious embryony is common in the Rutaceae containing Citrus crop species.
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