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1.
Elife ; 112022 01 18.
Artículo en Inglés | MEDLINE | ID: mdl-35040432

RESUMEN

Variation in floral displays, both between and within species, has been long known to be shaped by the mutualistic interactions that plants establish with their pollinators. However, increasing evidence suggests that abiotic selection pressures influence floral diversity as well. Here, we analyse the genetic and environmental factors that underlie patterns of floral pigmentation in wild sunflowers. While sunflower inflorescences appear invariably yellow to the human eye, they display extreme diversity for patterns of ultraviolet pigmentation, which are visible to most pollinators. We show that this diversity is largely controlled by cis-regulatory variation affecting a single MYB transcription factor, HaMYB111, through accumulation of ultraviolet (UV)-absorbing flavonol glycosides in ligules (the 'petals' of sunflower inflorescences). Different patterns of ultraviolet pigments in flowers are strongly correlated with pollinator preferences. Furthermore, variation for floral ultraviolet patterns is associated with environmental variables, especially relative humidity, across populations of wild sunflowers. Ligules with larger ultraviolet patterns, which are found in drier environments, show increased resistance to desiccation, suggesting a role in reducing water loss. The dual role of floral UV patterns in pollinator attraction and abiotic response reveals the complex adaptive balance underlying the evolution of floral traits.


Flowers are an important part of how many plants reproduce. Their distinctive colours, shapes and patterns attract specific pollinators, but they can also help to protect the plant from predators and environmental stresses. Many flowers contain pigments that absorb ultraviolet (UV) light to display distinct UV patterns ­ although invisible to the human eye, most pollinators are able to see them. For example, when seen in UV, sunflowers feature a 'bullseye' with a dark centre surrounded by a reflective outer ring. The sizes and thicknesses of these rings vary a lot within and between flower species, and so far, it has been unclear what causes this variation and how it affects the plants. To find out more, Todesco et al. studied the UV patterns in various wild sunflowers across North America by considering the ecology and molecular biology of different plants. This revealed great variation between the UV patterns of the different sunflower populations. Moreover, Todesco et al. found that a gene called HaMYB111 is responsible for the diverse UV patterns in the sunflowers. This gene controls how plants make chemicals called flavonols that absorb UV light. Flavonols also help to protect plants from damage caused by droughts and extreme temperatures. Todesco et al. showed that plants with larger bullseyes had more flavonols, attracted more pollinators, and were better at conserving water. Accordingly, these plants were found in drier locations. This study suggests that, at least in sunflowers, UV patterns help both to attract pollinators and to control water loss. These insights could help to improve pollination ­ and consequently yield ­ in cultivated plants, and to develop plants with better resistance to extreme weather. This work also highlights the importance of combining biology on small and large scales to understand complex processes, such as adaptation and evolution.


Asunto(s)
Adaptación Fisiológica , Helianthus/genética , Helianthus/fisiología , Pigmentación/genética , Rayos Ultravioleta , Flavonoles/metabolismo , Flavonoles/efectos de la radiación , Fenotipo , Polinización
2.
Acta Biol Hung ; 67(4): 403-411, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28000505

RESUMEN

The impact of short-term UV-B treatment on the content of individual flavonoids and photosynthetic pigments in cotyledons and the growth of common buckwheat (Fagopyrum esculentum Moench) seedlings was investigated. Seeds of four common buckwheat cultivars were germinated in darkness over a period of 4 days and acclimatized for 2 days under a 16/8 h light/dark photoperiod at 24/18 °C day/night, and exposure to 100-120 µmol ∙ m-2 ∙ s-1 of photosynthetically active radiation (PAR). Seedlings were divided into three batches, including two batches subjected to different doses of UV-B (5 W ∙ m-2 and 10 W ∙ m-2, one hour per day) for 5 days, and a control group exposed to PAR only. Exposure to UV-B increased anthocyanin levels in the cotyledons of all examined cultivars, it inhibited hypocotyl elongation, but did not affect the content of photosynthetic pigments. Flavone concentrations increased in cv. Red Corolla and Kora, remained constant in cv. Panda and decreased in cv. Hruszowska. Exposure to UV-B decreased rutin levels in cv. Hruszowska, but not in the remaining cultivars. Cultivars Hruszowska, Panda and Kora appeared to be less resistant to UV-B than Red Corolla. Higher resistance to UV-B radiation in Red Corolla can probably be attributed to its higher content of anthocyanins and rutin in comparison with the remaining cultivars.


Asunto(s)
Antocianinas/efectos de la radiación , Carotenoides/efectos de la radiación , Cotiledón/efectos de la radiación , Fagopyrum/efectos de la radiación , Flavonas/efectos de la radiación , Flavonoles/efectos de la radiación , Plantones/efectos de la radiación , Rayos Ultravioleta , Antocianinas/metabolismo , Carotenoides/metabolismo , Clorofila/metabolismo , Clorofila/efectos de la radiación , Cotiledón/metabolismo , Fagopyrum/crecimiento & desarrollo , Fagopyrum/metabolismo , Flavonas/metabolismo , Flavonoides/metabolismo , Flavonoides/efectos de la radiación , Flavonoles/metabolismo , Hipocótilo/crecimiento & desarrollo , Hipocótilo/efectos de la radiación , Fenoles/metabolismo , Fenoles/efectos de la radiación , Rutina/metabolismo , Rutina/efectos de la radiación , Plantones/crecimiento & desarrollo
3.
Chem Biodivers ; 4(7): 1525-32, 2007 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-17638334

RESUMEN

An early investigation at the Biosphere-2 Laboratory, an artificial ecosystem in the Arizona desert, had shown that the flavonoid content of cacti grown in glass-filtered solar light was lower than of cacti grown in normal solar light. This was attributed to the absence of ultraviolet (UV) radiation, which is required for flavonoid biosynthesis. In this study, two species of Opuntia cacti were grown in solar and UV-depleted light, and their flavonol contents of different tissues were determined by HPLC. O. wilcoxii, previously raised in the absence of UV light, was exposed to normal solar light. The flavonol content of young O. wilcoxii pads was 28-fold higher when grown in solar light as compared to UV-depleted light. The flavonol contents of mature outer tissues were only slightly higher. O. violacea, previously raised in solar light, was also maintained in the same UV-depleted artificial ecosystem. The flavonol content after hydrolysis of outer tissues was similar, whether grown in solar light or UV-depleted light. We attribute these responses to different biosynthetic and metabolic rates of young vs. mature plant tissues; slow-growing mature tissues neither produce nor metabolize compounds as quickly as immature tissues. These findings indicate that artificial ecosystems can influence the production of natural products in cultivated plants.


Asunto(s)
Flavonoles/efectos de la radiación , Opuntia/efectos de la radiación , Rayos Ultravioleta , Flavonoles/aislamiento & purificación , Opuntia/química , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/efectos de la radiación , Estructuras de las Plantas/química , Estructuras de las Plantas/efectos de la radiación , Luz Solar
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