Tansley Review No. 109.

Cogdell, Richard J.; Lindsay, J. Gordon

doi:10.1046/j.1469-8137.2000.00571.x

Cited by 31 publications

(14 citation statements)

References 160 publications

(270 reference statements)

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“…The RC is a transmembrane protein−pigment complex, and the energy trapped by it is converted to an electrochemical energy by charge separation against the electrostatic-potential gradient within the RC. Research on such initial electronic processes of photosynthesis has been explosively developed in these 15 years . Such a remarkable era was opened in 1984 by the first clarification of the three-dimensional structure of the RC from photosynthetic purple bacteria .…”

Section: Introductionmentioning

confidence: 99%

“…Structure determinations mentioned above have greatly promoted our understanding of photosynthesis as a function. The energy trapping begins with excitation transfer from the antenna system to the (so-called) special pair (P) of bacteriochlorophylls in bacterial photosynthesis (alternatively, to that of chlorophylls in higher plants, algae, and cyanobacteria) in the RC. , The excitation of P is very rapidly converted to a state of initial charge separation along one of the pigment strains within the RC by transferring an electron to the primary acceptor, which is bacteriopheophytin in purple bacteria. The distance between P and the primary acceptor is so large (∼17 Å in purple bacteria) that the electron transfer from P to the primary acceptor is mediated stepwise by a pigment (B) located between them .…”

Section: Introductionmentioning

confidence: 99%

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Uphill Energy Trapping by Reaction Center in Bacterial Photosynthesis: Charge Separation Unistep from Antenna Excitation, Virtually Mediated by Special-Pair Excitation

Sumi

2002

J. Phys. Chem. B

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In the primary process of photosynthesis, energy of the electronic excited state, A*, in the core antenna is trapped by the reaction center into a state, B, of charge separation between pigments therein. This energytrapping process is mediated by the excited state, P*, of the special pair of chlorophylls or bacteriochlorophylls in the reaction center. Energy transfer from A* to P* has been reported to be uphill with an excitation-energy difference, for example, amounting to about 200 and 350-400 cm -1 in Rhodobacter (Rb.) sphaeroides and Rhodopseudomonas (Rps.) Viridis, respectively, in purple bacteria. The rate constant of this energy-trapping process was calculated with special attention to these species, reproducing observed data in the whole temperature range. At physiological temperatures, this process proceeds by the ordinary sequential mechanism, in which the second step from P* to B takes place after thermalization of phonons at P*, in both species. The uphill excitation-energy difference in the first step from A* to P* is blurred out by thermal activation with nearly uniform rate constants of about (50 ps) -1 for the energy trapping at room temperature. In Rb. sphaeroides, P* is thermally (i.e., in the free energy) lower than A* by about 50 cm -1 because of reorganizing relaxation of the medium in association with excitation of pigments. Correspondingly therein, the energy-trapping process is determined by the ordinary sequential mechanism at all temperatures. In Rps. Viridis, P* is thermally still higher than A* by about 150 cm -1 . Correspondingly, below about 50 K therein, the energy-trapping process changes to the superexchange mechanism in which mediation at P* takes place as a quantum-mechanical virtual process without real population at P*. This mechanism resolves a serious difficulty that the observed data and the expectation from the ordinary sequential mechanism deviate to an astronomical extent at low temperatures in Rps. Viridis.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Uphill Energy Trapping by Reaction Center in Bacterial Photosynthesis: Charge Separation Unistep from Antenna Excitation, Virtually Mediated by Special-Pair Excitation

Sumi

2002

J. Phys. Chem. B

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“…In many dioecious plant species, male and female plants are different not only in their sexual organs but also in their morphological, physiological and life history traits. Such sexual dimorphism is typically related to differences in reproductive costs associated with male and female functions (Dawson and Geber 1999;Obeso 2002; Barrett and Hough 2013). Females produce flowers and fruits, and therefore, they usually invest more carbon in reproduction than males.…”

Section: Introductionmentioning

confidence: 99%

“…However, in some species, particularly in windpollinated herbs, allocation of certain resources (e.g., nitrogen) to flowers alone may be considerably higher for males (Harris and Pannell 2008). The greater investment of limiting resources to reproduction by one of the sexes may come at the expense of reduced investment of those resources to other functions, such as growth and defence (Obeso 2002). Sex-related differences may be affected by the environmental context (Retuerto et al 2018), and when experiencing stressful conditions, we may expect the sex with higher investment in reproduction to have reduced performance (Juvany and Munné-Bosch 2015).…”

Section: Introductionmentioning

confidence: 99%

Sexual dimorphism in response to herbivory and competition in the dioecious herb Spinacia oleracea

Pérez-Llorca

Vilas

2019

Plant Ecol

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Sexual dimorphism is common in dioecious plant species and is usually attributed to different cost of reproduction associated with male and female functions. Differences in growth and performance between male and female plants may be accentuated under stress, potentially leading to sex-ratio biases and affecting population growth. Environmental stress involves multiple factors that often occur simultaneously. Among different stress combinations that occur in field conditions, competition and herbivory and their interaction are key biotic factors that can affect plant growth and performance. Here, we conducted a glasshouse experiment in Cardiff, UK, using the cultivated spinach, Spinacia oleracea, as a model system to study sexual dimorphism in intra-and interspecific competitive ability and in response to herbivory by a generalist herbivore Helix aspersa. We found stronger inter-than intra-specific competition: growth (above-ground biomass) and chlorophyll content of male and female plants was reduced when growing with Brassica oleracea, but not when growing with conspecifics. In the absence of herbivory, females growing with same-sex neighbour had greater root biomass than males; whilst herbivory reduced root biomass significantly only in females competing with same sex neighbours. Plant damage caused by herbivores was similar when growing with male or female conspecifics but greater when growing with B. oleracea. Finally, plant damage caused by herbivores did not differ between male and female plants; however, males increased their allocation to roots and reduced their chlorophyll content after damage. Our results showed that sexual dimorphism occurs in S. oleracea, despite being a worldwide crop, selectively bred for its edible leaves. In particular, our results suggest stronger same-sex competition for females and greater tolerance to herbivory in males than in females of S. oleracea..

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“…Once unisexuality has evolved, selection may 57 favour further divergence between the sexes as consequence of their different reproductive 58 roles (production of seeds vs. pollen). Sexual dimorphism in plants is quite common (Barrett 59 and Hough, 2013; Willson, 1991) and males and females usually differ in their vegetative 60 morphology Obeso, 2002 Sexual dimorphism has been commonly attributed to the different cost of reproduction in 67 males vs. females, namely, as the result of trade-offs between allocation to reproduction and 68 to other functions (e.g., to growth and/or defence). Such trade-offs are likely to be accentuated 69 under more stressful conditions, such as under nutrient-deficient soil, strong competition from 70 other plants, or herbivory.…”

Section: Introduction 51mentioning

confidence: 99%