Apomixis beyond trees in the Brazilian savanna: new insights from the orchid Zygopetalum mackayi .

Autor:	da Costa GV; Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil.; Programa de Pós-Graduação em Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil., Alves MF; Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil.; Programa de Pós-Graduação em Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil., Duarte MO; Instituto de Biologia, Universidade Federal de Uberlândia, Rua Ceará s/n, 38405-302 Uberlândia, MG, Brazil., Caetano APS; Instituto de Biociências, Universidade Federal do Mato Grosso, Av. Fernando Correa da Costa  2367, 78060-900 Cuiabá, MT, Brazil., Koehler S; Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil.; Programa de Pós-Graduação em Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil., Mayer JLS; Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil.; Programa de Pós-Graduação em Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, Rua Monteiro Lobato 255, 13083-862 Campinas, SP, Brazil.
Jazyk:	angličtina
Zdroj:	AoB PLANTS [AoB Plants] 2024 Jun 27; Vol. 16 (4), pp. plae037. Date of Electronic Publication: 2024 Jun 27 (Print Publication: 2024).
DOI:	10.1093/aobpla/plae037
Abstrakt:	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 Zygopetalum mackayi , 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 x , 3 x , 4 x ) of this species. Flowers and fruits at different stages were collected to describe the development and morphology of ovules and seeds considering sexual and apomictic processes. As self-pollination treatments resulted in high fruit abortion in diploids, we also examined pollen tube development in aborted flowers and fruits to search for putative anomalies. Megasporogenesis and megagametogenesis occur regularly in all cytotypes. Apomixis is facultative and sporophytic, and associated with polyploid cytotypes, while diploid individuals exclusively engage in sexual reproduction. Polyembryony is caused mainly by the production of adventitious embryos from nucellar cells of triploids and tetraploids, but also by the development of multiple archesporia in all cytotypes. Like other apomictic angiosperms within the Brazilian savanna, our findings demonstrate that apomixis in Z. mackayi relies on pollinators for seed production. We also consider the ecological implications of these apomictic patterns in Z. mackayi within the context of habitat loss and its dependence on pollinators. Competing Interests: None declared. (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company.)
Databáze:	MEDLINE
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