Evolution of the outer ovule integument and its systematic significance in Melastomataceae

Caetano, Ana Paula Souza; Basso-Alves, João Paulo; Cortez, Priscila Andressa; Brito, Vinícius Lourenço Garcia de; Michelangeli, Fabián A.; Reginato, Marcelo; Goldenberg, Renato; Carmello-Guerreiro, Sandra Maria; Teixeira, Simone de Pádua

doi:10.1093/botlinnean/box093

Cited by 11 publications

(5 citation statements)

References 81 publications

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“…These processes are coordinated with the endosperm (Coen et al ., 2017). The OI grows faster than the II and extends beyond the apex of the nucellus first (Souza-Caetano et al ., 2018). The II grows as a radially symmetrical structure to envelop the terminal nucellus whereas OI grows asymmetrically.…”

Section: Evolutionary Alterations Of the Seed Coat: Unitegmy And Bitegmymentioning

confidence: 99%

Seed coat formation: its evolution and regulation

Matilla

2019

Seed Sci. Res.

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In higher plants, the seed precursor (ovule primordia) is composed of three parts: funiculus, nucellus and chalaza, generating the latter one (II) or two (OI and II) protective maternal integuments (seed coat, SC). The appearance of a viable seed requires the coordinate growth and development of the preceding three compartments. Integuments are essentials for seed life as they nourish, protect and facilitate seed dispersion. Endosperm and integument growth and development are tightly coupled. Gymnosperm and angiosperm ovules are commonly unitegmic and bitegmic, respectively. Unusually, ategmy and threetegmy (OI, II and aril) also exist. The expression of the INO, ATS and ETT genes, involved in integument development, seems to have demonstrated that the fusion of OI and II leads to the appearance of unitegmy in higher plants. Likewise, INO expression also manifests the conservation of OI during evolution. The molecular control of SC development is constituted by a signalling network with still a multitude of gaps. The fertilization-independent development of the ovule is repressed by the FERTILIZATION INDEPENDENT SEED (FIS), a Polycomb-Repressive-Complex-2 (PRC2). Both endosperm and SC development are tightly linked to PRC2 function. As in many other developmental processes, auxin plays an essential role during ovule and SC development. Auxin transport from the endosperm to the integuments is regulated by AGL62 (AGAMOUS-LIKE 62), the encoding gene of which is specifically expressed in the endosperm to suppress its cellularization. In the absence of AGL62 (i.e. agl62 mutants), auxin remains trapped in the endosperm and the SC fails to develop (i.e. seed abortion). This update shows that auxin biosynthesis, transport and signalling play a predominant role and seem to be absolutely required in the pathway(s) that lead to SC formation, most likely not as a unique hormonal component.

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Section: Evolutionary Alterations Of the Seed Coat: Unitegmy And Bitegmymentioning

confidence: 99%

Seed coat formation: its evolution and regulation

Matilla

2019

Seed Sci. Res.

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“…For example, in Olacaceae, there are described bitegmic, unitegmic, and ategmic species (Brown et al, 2010). In Melastomataceae, ovules are bitegmic; however, in species of the same genus, the number of the outer integument layers can vary from two to many (Caetano et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Another hypothesis is that the number of integument layers could be related to the fruit type and seed dispersal mode. A study performed with several species of Melastomataceae tried to confirm if there was a relationship between ovules with multiseriate outer integument and fleshy fruits (Caetano et al, 2018). The data obtained did not confirm this relation; however, ancestral state reconstruction shows a tendency for ovules with multiseriate outer integument to occur in fleshy fruit clades.…”

Section: Introductionmentioning

confidence: 99%

First Record of Ategmic Ovules in Orchidaceae Offers New Insights Into Mycoheterotrophic Plants

et al. 2019

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The number of integuments found in angiosperm ovules is variable. In orchids, most species show bitegmic ovules, except for some mycoheterotrophic species that show ovules with only one integument. Analysis of ovules and the development of the seed coat provide important information regarding functional aspects such as dispersal and seed germination. This study aimed to analyze the origin and development of the seed coat of the mycoheterotrophic orchid Pogoniopsis schenckii and to compare this development with that of other photosynthetic species of the family. Flowers and fruits at different stages of development were collected, and the usual methodology for performing anatomical studies, scanning microscopy, and transmission microscopy following established protocols. P. schenckii have ategmic ovules, while the other species are bitegmic. No evidence of integument formation at any stage of development was found through anatomical studies. The reduction of integuments found in the ovules could facilitate fertilization in this species. The seeds of P. schenckii, Vanilla planifolia, and V. palmarum have hard seed coats, while the other species have seed coats formed by the testa alone, making them thin and transparent. P. schenckii, in contrast to the other species analyzed, has a seed coat that originates from the nucellar epidermis, while in other species, the seed coat originates from the outer integument.

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“…Antilhas até a Argentina, concentrando-se principalmente no cerrado e campo rupestre, nas savanas da região amazônica e nos planaltos das Guianas (Rocha et al 2018). Embora apresentam uma considerável diversidade floral, a maioria dos seus representantes compartilham a presença de flores 4-meras, ovários 4loculares, ou menos comumente 2-3-loculares, glabros ou com tricomas glandulosos e sementes cocleadas (Rocha et al 2016(Rocha et al , 2018, bem como a presença de três camadas no integumento do ovário como potencial sinapomorfia (Caetano et al 2018).…”

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Flora da Serra do Cipó, Minas Gerais: Marcetieae (Melastomataceae)

et al. 2020

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Este estudo visa ampliar o conhecimento sobre a família Melastomataceae na Serra do Cipó, Minas Gerais e, consequentemente, agregar novos dados ao projeto “Flora da Serra do Cipó, Minas Gerais”. Marcetieae é uma tribo recentemente descrita, representada no Brasil por 112 espécies e 18 gêneros, ocorrendo predominantemente na savana amazônica, cerrado, campo rupestre e, mais raramente, em ambientes florestais. Até o momento foram registradas na Serra do Cipó 15 espécies e seis gêneros, sendo Fritzschia o gênero mais representativo com seis espécies, seguido por Marcetia e Siphanthera com três espécies cada, e Aciotis, Acisanthera e Macairea com apenas uma espécie cada. São apresentadas chaves de identificação para os gêneros e espécies, descrições, pranchas de campo e notas taxonômicas, incluindo informações sobre distribuição geográfica e habitat.

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Evolution of the outer ovule integument and its systematic significance in Melastomataceae

Cited by 11 publications

References 81 publications

Seed coat formation: its evolution and regulation

Seed coat formation: its evolution and regulation

First Record of Ategmic Ovules in Orchidaceae Offers New Insights Into Mycoheterotrophic Plants

Flora da Serra do Cipó, Minas Gerais: Marcetieae (Melastomataceae)

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