Did apomixis evolve from sex or was it the other way around?
Autor: | Emidio Albertini, Gianni Barcaccia, John G. Carman, Fulvio Pupilli |
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Rok vydání: | 2019 |
Předmět: |
0106 biological sciences
0301 basic medicine Physiology Plant Science Biology 01 natural sciences Plant reproduction Magnoliopsida 03 medical and health sciences plant reproduction Meiosis Polyphenism Apomixis meiosis origins of sex parthenogenesis Ovule epigenetics Reproduction Embryo Apomeiosis apomixis eukaryogenesis Parthenogenesis Biological Evolution 030104 developmental biology Evolutionary biology Megaspore Apomeiosis apomixis eukaryogenesis meiosis origins of sex parthenogenesis plant reproduction 010606 plant biology & botany |
Zdroj: | Journal of experimental botany (Online) 70 (2019): 2951–2964. doi:10.1093/jxb/erz109 info:cnr-pdr/source/autori:Albertini E.; Barcaccia G.; Carman J.G.; Pupilli F./titolo:Did apomixis evolve from sex or was it the other way around?/doi:10.1093%2Fjxb%2Ferz109/rivista:Journal of experimental botany (Online)/anno:2019/pagina_da:2951/pagina_a:2964/intervallo_pagine:2951–2964/volume:70 |
ISSN: | 1460-2431 0022-0957 |
Popis: | In angiosperms, there are two pathways of reproduction through seeds: sexual, or amphimictic, and asexual, or apomictic. The essential feature of apomixis is that an embryo in an ovule is formed autonomously. It may form from a cell of the nucellus or integuments in an otherwise sexual ovule, a process referred to as adventitious embryony. Alternatively, the embryo may form by parthenogenesis from an unreduced egg that forms in an unreduced embryo sac. The latter may form from an ameiotic megasporocyte, in which case it is referred to as diplospory, or from a cell of the nucellus or integument, in which case it is referred to as apospory. Progeny of apomictic plants are generally identical to the mother plant. Apomixis has been seen over the years as either a gain- or loss-of-function over sexuality, implying that the latter is the default condition. Here, we consider an additional point of view, that apomixis may be anciently polyphenic with sex and that both reproductive phenisms involve anciently canalized components of complex molecular processes. This polyphenism viewpoint suggests that apomixis fails to occur in obligately sexual eukaryotes because genetic or epigenetic modifications have silenced the primitive sex apomixis switch and/or disrupted molecular capacities for apomixis. In eukaryotes where sex and apomixis are clearly polyphenic, apomixis exponentially drives clonal fecundity during reproductively favorable conditions, while stress induces sex for stress-tolerant spore or egg formation. The latter often guarantees species survival during environmentally harsh seasons. |
Databáze: | OpenAIRE |
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