Amino acids and protein profile in floral nectar: Much more than a simple reward

Nepi, Massimo; Soligo, Chiara; Nocentini, Daniele; Abate, Milagros B.; Guarnieri, Massimo; Cai, Giampiero; Bini, Luca; Puglia, Michele; Bianchi, Laura; Pacini, Ettore

doi:10.1016/j.flora.2012.06.002

Cited by 97 publications

(98 citation statements)

References 53 publications

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“…Plants also offer a nectar reward for protection. Recent studies (Nepi et al 2012) demonstrated that nectar may have other functions in addition to attracting pollinators: defence against microbial invasion. Nectar has been considered a major floral reward for animals because it is predominantly composed of sugar, but also protein and nonprotein amino acids and essential and nonessential amino acids have been detected.…”

Section: Reward: Pollen and Nectarmentioning

confidence: 99%

Grain Legumes

2015

Handbook of Plant Breeding

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The field of plant breeding covers a broad range of different species and categories of plants. While there are many techniques and issues that are similar across these species, many more are unique to each genus.The Handbook of Plant Breeding is organized by major crop categories and includes the most up-to-date molecular techniques being used. It will serve as a resource for plant breeding laboratories in both the university and industrial setting.More information about this series at

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Section: Reward: Pollen and Nectarmentioning

confidence: 99%

Grain Legumes

2015

Handbook of Plant Breeding

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“…In addition to the transcriptional activation of the floral Pro transporter (Schwacke et al, 1999), high levels of Pro in flower are obtained via up-regulation of the pyrroline-5-carboxylate synthetase enzyme, which catalyzes the conversion of Glu to pyrroline-5-carboxylate (Kavi Kishor et al, 2015). Interestingly, Pro is the most abundant amino acid in nectar, regardless of the evolutionary distance between plant species (Carter et al, 2006;Nepi et al, 2012). This suggests that Pro may have a relevant ecological role for rewarding animal pollinators (Carter et al, 2006).…”

Section: Floral Amino Acids: Synthesis and Functionmentioning

confidence: 99%

“…For example, Phe-and GABA-enriched nectars are commonly represented in plants pollinated by long-tongued bees and flies independently of their taxonomic group. As GABA functions as an inhibitory neurotransmitter of insects' nervous systems, GABA-rich nectar may be preferred by pollinators for its calming effect (Nepi et al, 2012). The volume of secreted nectar also varies in response to pollinators' preferences, and this happens more rapidly than initially thought.…”

Section: Primary Metabolites and Pollinators' Preferences: Implicatiomentioning

confidence: 99%

Floral Metabolism of Sugars and Amino Acids: Implications for Pollinators’ Preferences and Seed and Fruit Set

Borghi

Fernie

2017

Plant Physiol.

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Primary metabolism in flowers sustains a plenitude of physiological and ecological functions related to floral development and plant reproduction. Carbohydrates and amino acids provide energy and precursors for the reactions of floral secondary metabolism, such as the molecules for color and scent, and constitute an important resource of food for the pollinators. Recent discoveries have advanced our understanding of the cycles of carbohydrate hydrolysis and resynthesis that regulate pollen development, pollen tube growth, and pollination as well as the composition of nectar. Pathways of de novo amino acid biosynthesis have been described in flowers, and the proteins that regulate pollen tube guidance and ultimately control fertilization are being progressively characterized. Finally, a novel field of research is emerging that investigates the chemical modification of sugars and amino acids by colonizing microorganisms and how these affect the pollinators' preferences for flowers. In this Update article, we provide an overview of the new discoveries and future directions concerning the study of the primary metabolism of flowers.The chemistry of flowers is unique, as it sustains very diverse physiological functions such as flower development, the transition from flower to fruit, and the initial phases of seed set (O'Neill, 1997;Pélabon et al., 2015). In addition, floral metabolites fulfill relevant ecological roles, such as acting as signaling molecules in the chemical communication with animal pollinators (Borghi et al., 2017), providing protection against pests and colonizing microorganisms (Kessler and Baldwin, 2007;Nepi, 2014). Stunning displays of the metabolic resources of flowers are, for example, their colors and fragrance, which occur following the accumulation and emission of tinted and scented secondary metabolites, respectively (Grotewold, 2006;Tanaka et al., 2008;Khan and Giridhar, 2015). Perhaps less sensational, but equally as important, are the reactions of primary metabolism. Indeed, these sustain the physiology of flowers, provide the chemical precursors, and meet the energy demand of floral secondary metabolism (Muhlemann et al., 2014). Moreover, sugars and amino acids also serve as a nutritional reward for the pollinators that feed on nectar and pollen (Pacini et al., 2006;Heil, 2011;Roy et al., 2017). Therefore, knowing how primary metabolites are imported or de novo synthesized in flowers, and how they are secreted and catabolized, is at the heart of floral biology, being relevant to understand the physiology of plant reproduction and the role that flowers play in the ecosystem. In this article, we aim to provide an overview of floral central metabolism. How primary metabolism sustains flower development, and fruit and seed set, also will be addressed. Finally, given the considerable proportion of primary metabolites that are channeled into nectar, we will discuss the chemical composition of nectar, the modifications that arise from fermentation processes by colonizing yeasts and bacteria, an...

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“…), Cucurbita pepo (Nepi et al . ) and in the extrafloral nectar of several Acacia species (Heil et al . ) and Humboldtia brunonis (Shenoy et al .…”

Section: Sugar Stabilitymentioning

confidence: 99%

“…Nepi et al . () demonstrated that invertase activity does not have the ability to modify nectar sugar proportions significantly during the 6‐h anthesis of C. pepo . It is unknown whether invertase can hydrolyse sucrose after nectar has been sampled and stored.…”

Section: Sugar Stabilitymentioning

confidence: 99%

A review of the methods for storing floral nectars in the field

Amato

Petit

2017

Plant Biol J

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The knowledge of floral nectar sugar characteristics, such as concentration, ratio and mass, is essential to understand the complex nature of nectar production and pollination systems. Although nectar is commonly stored in ecology, storage reliability and effectiveness have rarely been quantified. Inappropriate nectar storage between sampling and analysis can alter nectar chemistry as a result of enzyme or microbial action. Our review of the literature indicates that measures to preserve nectar sugars before analysis include refrigeration, freezing, the addition of an antimicrobial agent, spotting and drying on filter paper, the addition of a desiccant or a combination of these storage treatments. Nectar stored on filter paper is removed by washing with a solvent before analysis. Elution methods are often complex, not standardised and poorly reported in published work. Existing storage methods have generally been used without an evaluation of their impact on results, but evidence suggests a potentially large impact on result accuracy. Future studies should report storage treatments and elution methods to legitimise comparison among independent studies and provide unbiased evaluation of the results. In view of the wide range of storage methods used and lack of verification of their appropriateness, is imperative that standardised and effective methods be developed to ensure that results are reliable. We recommend the prompt analysis of nectar, detailed description of methods, including size of filter paper and method of elution, and use of sterile techniques.

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Amino acids and protein profile in floral nectar: Much more than a simple reward

Cited by 97 publications

References 53 publications

Grain Legumes

Grain Legumes

Floral Metabolism of Sugars and Amino Acids: Implications for Pollinators’ Preferences and Seed and Fruit Set

A review of the methods for storing floral nectars in the field

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