Multifunctionality of angiosperm floral bracts: a review.

Autor: Song B; Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China., Chen J; Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China.; School of Life Sciences, Yunnan University, Huannan Road, East of University Town, Chenggong New Area, Kunming, 650500, China., Lev-Yadun S; Department of Biology and Environment, Faculty of Natural Sciences, University of Haifa at Oranim, Kiryat Tiv'on, 36006, Israel., Niu Y; Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China., Gao Y; Yunnan Forestry Technological College, 1 Jindian, Kunming, 650224, China., Ma R; Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China., Armbruster WS; School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry I Street, Portsmouth, PO1 2DY, UK.; Institute of Arctic Biology, University of Alaska, PO Box 757000, Fairbanks, AK, 99775, USA., Sun H; Key Laboratory for Plant Diversity and Biogeography of East Asia/Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming, 650201, China.
Jazyk: angličtina
Zdroj: Biological reviews of the Cambridge Philosophical Society [Biol Rev Camb Philos Soc] 2024 Jun; Vol. 99 (3), pp. 1100-1120. Date of Electronic Publication: 2024 Jan 30.
DOI: 10.1111/brv.13060
Abstrakt: Floral bracts (bracteoles, cataphylls) are leaf-like organs that subtend flowers or inflorescences but are of non-floral origin; they occur in a wide diversity of species, representing multiple independent origins, and exhibit great variation in form and function. Although much attention has been paid to bracts over the past 150 years, our understanding of their adaptive significance remains remarkably incomplete. This is because most studies of bract function and evolution focus on only one or a few selective factors. It is widely recognised that bracts experience selection mediated by pollinators, particularly for enhancing pollinator attraction through strong visual, olfactory, or echo-acoustic contrast with the background and through signalling the presence of pollinator rewards, either honestly (providing rewards for pollinators), or deceptively (attraction without reward or even trapping pollinators). However, studies in recent decades have demonstrated that bract evolution is also affected by agents other than pollinators. Bracts can protect flowers, fruits, or seeds from herbivores by displaying warning signals, camouflaging conspicuous reproductive organs, or by providing physical barriers or toxic chemicals. Reviews of published studies show that bracts can also promote seed dispersal and ameliorate the effects of abiotic stressors, such as low temperature, strong ultraviolet radiation, heavy rain, drought, and/or mechanical abrasion, on reproductive organs or for the plants' pollinators. In addition, green bracts and greening of colourful bracts after pollination promote photosynthetic activity, providing substantial carbon (photosynthates) for fruit or seed development, especially late in a plant's life cycle or season, when leaves have started to senesce. A further layer of complexity derives from the fact that the agents of selection driving the evolution of bracts vary between species and even between different developmental stages within a species, and selection by one agent can be reinforced or opposed by other agents. In summary, our survey of the literature reveals that bracts are multifunctional and subject to multiple agents of selection. To understand fully the functional and evolutionary significance of bracts, it is necessary to consider multiple selection agents throughout the life of the plant, using integrative approaches to data collection and analysis.
(© 2024 Cambridge Philosophical Society.)
Databáze: MEDLINE
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