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Summary: Greenbeards are selfish genetic elements that make their bearers behave either altruistically towards individuals bearing similar greenbeard copies or harmfully towards individuals bearing different copies. They were first proposed by W. D. Hamilton over 50 yr ago, to illustrate that kin selection may operate at the level of single genes. Examples of greenbeards have now been reported in a wide range of taxa, but they remain undocumented in plants. In this paper, we discuss the theoretical likelihood of greenbeard existence in plants. We then question why the greenbeard concept has never been applied to plants and speculate on how hypothetical greenbeards could affect plant–plant interactions. Finally, we point to different research directions to improve our knowledge of greenbeards in plants. [ABSTRACT FROM AUTHOR]

The Scholander-Hammel pressure chamber has been used in thousands of papers to measure osmotic pressure, πc, turgor pressure, Pt, and bulk modulus of elasticity, ε, of leaf cells by pressure-volume ( PV) curve analysis. PV analysis has been questioned in the past., In this paper we use micromechanical analysis of leaf cells to examine the impact on PV curve analysis of negative turgor in living cells ( Pt)., Models predict negative Pt (−0.1 to −1.8 MPa) depending on leaf cell size and shape in agreement with experimental values reported by J. J. Oertli. Modeled PV curves have linear regions even when Pt is quite negative, contrary to the arguments of M.T. Tyree. Negative Pt is totally missed by PV curve analysis and results in large errors in derived πc and Pt but smaller errors in ε., A survey of leaf cell sizes vs habitat (arid, temperate, and rainforest), suggests that the majority of published PV curves result in errors of 0.1-1.8 MPa in derived πc and Pt, whereby the error increases with decreasing cell size. We propose that small cell size in leaves is an ecological adaptation that permits plants to endure negative values of water potential with relatively little water loss. [ABSTRACT FROM AUTHOR]

This paper describes the ecology of a coastal alluvial plain at Chichiriviche in northern Venezuela. The area supports a great diversity of plant communities, ranging from mangroves on the seaward edge of the plain to non-halophytic, fresh-water communities on the landward side. Small differences on topography result in a mosaic of saline and less-saline environments . Rainfall is strongly seasonal, causing superficial flooding of the alluvial plain in the rainy season and the creation of a hypersaline substratum during the dry season. As a consequence, much of the plain is devoid on vegetation. Towards the landward side of the plain there are numerous small 'vegetation islands', fringed by halophilic succulent herbs, and made up of deciduous and semi-deciduous shrubs and trees together with non-halophytic CAM plants such as cacti and bromeliads. In subsequent papers the results of ecophysiological studies of these diverse plant species are presented. [ABSTRACT FROM AUTHOR]

The influence of number of seeds per clump upon germination of Plantago coronopus L. was investigated at different salinity levels on filter paper, sand and soil. These substrates provide both artificial and semi-natural microenvironments for seed germination. On all substrates, germination was positively dependent on clump density and seeds in clumps had a higher tolerance of salinity as reflected in higher germination percentages. Final percentage germination for a given clump size and salinity level depended upon substrate, being far higher on filter paper and sand than on soil, whilst the time required to reach final germination also increased in that order. The possible ecological significance of density-dependent seed germination is discussed. [ABSTRACT FROM AUTHOR]

In a previous paper (Faiz and Weatherley, 1977), evidence was put forward for the development of steep gradients of water potential in the soil surrounding the individual roots of rapidly transpiring plants (perirhizal gradients). In this paper, similar experiments are described in which additional data on the dimensions of the root system, distribution of soil water potentials within the rooting zone and the water potentials of the roots themselves were obtained. It was found with experiments on soil that the surface area of the root system was X 60 the cross-sectional area of the pararhizal pathway (cross-sectional area of the pot) through which water moved to the root zone from the water table below. Since the volume rate of flow through the pen- and pararhizal zones was the same, the velocity of movement up to the individual root was therefore only 1/60 of that through the soil supplying the root system. Under conditions of rapid transpiration, the gradient of water potential in that part of the pararhizal pathway immediately beneath the root zone was found to be about 1 bar cm-1. Thus it would be expected that the perirhizal gradient would be 1/60 of this, i.e. it would be negligibly small. However, the actual perirhizal drop in water potential was found to be about 8 bars through a distance of 0.1 cm, i.e. the gradient was 80 bars cm1. Such a steep gradient would require the hydraulic conductivity of the soil in the perirhizal zones to be 4 orders of magnitude lower than that in the pararhizal pathway. An even greater discrepancy was found with fine sand. The soil within the rooting zone had a somewhat lower water content than that in the pararhizal zone, but it is not thought that this, and some other imponderables which are discussed, could account for this enormous discrepancy. It is concluded that in these experiments, measurable perirhizal gradients were unlikely to develop. [ABSTRACT FROM AUTHOR]

A method for the combined estimation of caffeine, theophylline and theobromine in plant material is presented. The method involved a chloroform-ammonia extraction, separation of the bases in the chloroform extract by thin layer or paper chromatography and finally estimation of the eluted bases by spectrophotometry. Good recoveries of all three compounds were recorded. The method was used to estimate the level of these compounds in tea, coffee beans and cocoa cotyledons. [ABSTRACT FROM AUTHOR]

• Functional–structural plant models that include detailed mechanistic representation of underlying physiological processes can be expensive to construct and the resulting models can also be extremely complicated. On the other hand, purely empirical models are not able to simulate plant adaptability and response to different conditions. In this paper, we present an intermediate approach to modelling plant function that can simulate plant response without requiring detailed knowledge of underlying physiology.• Plant function is modelled using a‘canonical’ modelling approach, which uses compartment models with flux functions of a standard mathematical form, while plant structure is modelled using L-systems.• Two modelling examples are used to demonstrate that canonical modelling can be used in conjunction with L-systems to create functional–structural plant models where function is represented either in an accurate and descriptive way, or in a more mechanistic and explanatory way.• We conclude that canonical modelling provides a useful, flexible and relatively simple approach to modelling plant function at an intermediate level of abstraction.New Phytologist(2005)doi: 10.1111/j.1469-8137.2005.01330.x© New Phytologist(2005) [ABSTRACT FROM AUTHOR]

• This paper presents an architectural model of wheat (Triticum aestivum), designed to explain effects of light conditions at the individual leaf level on tillering kinetics. Various model variables, including blade length and curvature, were parameterized for spring wheat, and compared with winter wheat and other Gramineae species.• The architectural model enables simulation of plant properties at the level of individual organs. Parameterization was based on data derived from an outdoor experiment with spring wheat cv. Minaret.• Final organ dimensions of tillers could be modelled using the concept of relative phytomer numbers. Various variables in spring wheat showed marked similarities to winter wheat and other species, suggesting possibilities for a general Gramineae architectural model.• Our descriptive model is suitable for our objective: investigating light effects on tiller behaviour. However, we plan to replace the descriptive modelling solutions by physiological, mechanistic solutions, starting with the localized production and partitioning of assimilates as affected by abiotic growth factors.New Phytologist(2005)doi: 10.1111/j.1469-8137.2005.01337.x© New Phytologist(2005) [ABSTRACT FROM AUTHOR]

• The emergence of a regular phyllochron from the dynamic processes of leaf initiation, leaf elongation and whorl construction suggests causal relationships between leaf elongation and leaf emergence. This paper presents a hypothesis as to how the ontogeny of the growth zone of leaves is triggered by emergence events, and implements it in a dynamic model of leaf elongation.• Two different experiments, presenting two contrasted cases of relationships between leaf emergence and kinetics of leaf elongation, were analysed and interpreted with the model in terms of the functioning of the growth zone.• Analysis of elongation kinetics revealed that the hypothesis allows for several contrasted elongation patterns that were observed, and for a regular phyllochron emerging from the variable dynamic of elongation. The model was able to simulate these patterns, and helped to identify the mechanisms underlying the key points of the analysis.• The hypothesis is not demonstrated, but its coherence and robustness are established, which should inform a renewal of the modelling of leaf elongation in architectural models.New Phytologist(2005)doi: 10.1111/j.1469-8137.2005.01371.x© New Phytologist(2005) [ABSTRACT FROM AUTHOR]

Summary The aim of this paper is to survey the general area of quantitative trait locus (QTL) mapping, and its specific impact on current understanding of plant domestication. Plant domestication is not only of historical interest, but is also of ongoing importance as changing human needs and availability of nonrenewable resources impel continuing (and perhaps even accelerated) investigation of prospective new crops. New genomic tools applied in conjunction with now-established approaches such as QTL mapping are opening new doors into searches for the ‘footprints’ of domestication, and promise to accelerate and streamline the identification of specific genes integral to domestication(s), building on early successes. Better understanding of plant domestication promises to enhance knowledge about the developmental basis of some of the more striking evolutionary events known, to guide efforts to catalog plant biodiversity, and to accelerate progress in improving existing and new crops to sustain humanity. [ABSTRACT FROM AUTHOR]

If metal tolerant plants, by virtue of their tolerance mechanism, are less efficient at the uptake, distribution or utilization of metals then essential micronutrient deficiency may occur at the low levels of metal supply found on non-mine soils. This argument forms the basis of the metal requirement hypothesis put forward to explain the lower fitness of tolerant individuals on uncontaminated soil, the so called 'cost of tolerance;. In this paper, copper balance was investigated in Mimulus guttatus Fischer ex. DC (the yellow monkey flower) for plants with or without the major tolerance gene which confers primary tolerance, and plants with few or many modifier genes which control degree of tolerance. No conclusive evidence to support an increased copper requirement in plants with the major tolerance gene, and/or may modifier genes was shown. Any differences in copper requirement found during vegetative growth were small, and were deemed insufficient to explain the apparent cost of tolerance. [ABSTRACT FROM AUTHOR]

This paper describes the effects of the fungicides Benlate, Aliette and Ridomil on plant growth and on mycorrhizal development in onion plants. An attempt was made to distinguish effects on plants from those on the fungus by making comparisons between mycorrhizal plants in the absence of added phosphorus and non-mycorrhizal equivalent size plants. Vital staining techniques were used to analyse the effects of the fungicides on the living fungus both within the root and in the soil. Benlate had no effect on shoot dry weight or root length of onion plants whereas a reduction in plant growth was observed following the application of Aliette or Ridomil, in comparison to control plants. Benlate had negative effects on the num,bers of living internal hyphe, arbuscules, fungal plant interface and living external hyphae in the soil. Aliette had no effect on the number of living intercellular hyphae and arbuscules. However, it markedly reduced the root length and the length of infected root per plant. There length of external hyphae per gram of soil was reduced following the application of aliette, though not as severely as with Benlate. Ridomil had more complex effects on vesicular-arbuscular mycorrhizal symbiosis; treated plants showed a reduction in plant growth and also reduction in all fungal parameters, namely the number of living intercellular hyphae, arbuscules and fungal-plant interface, the length of infested root and the development of external hyphae in the soil. [ABSTRACT FROM AUTHOR]

This paper reports a comparison of the effects of the same ozone exposure given at different stages of growth on a population major L., which is as sensitive to ozone as Bel-W3 tobacco. Plants were grown from seed for eight weeks in controlled environment chambers and exposed to 70 μl O3 l-1 7 h d-1 for the whole period or for 2-wk episodes during weeks 1+2, 3+4, 5+6 or 7+8. Controls had charcoal filtered air. Effects on leaf, flower, seed and dry matter production, and on relative growth rate of shot and root are given. At whatever time the ozone was given it altered relative growth rate, dry matter partitioning and seed output. The experiment supports the view that assessment of the sensitivity of a herbaceous species can be indicated by a short-term exposure of young plants, even though the nature of the response may change with development. Comparison of the effect of ozone on dry matter partitioning at different stages of growth suggested that at each stage in development, ozone relatively strengthened the currently dominant sink, therefore reducing allocation to subsidiary sinks. As a plant develops, the relative strengths of sources and sinks change so the effects of an ozone episode on allocation will depend upon the timing. It is concluded that the commonly held view that ozone tends to reduce root growth more than shoot may be an over-simplification. For native plants growing in the field, the timing of episodes in relation to development may be crucial to understanding ozone impact. On the ecosystem level we need knowledge of response and source - sink relationships at times of the year when episodes occur. [ABSTRACT FROM AUTHOR]

The long period covered by this paper probably saw the most drastic changes wrought by man on the plant cover of these islands in the whole of postglacial history. Much of our information about vegetation changes comes from those parts of the country where peats and mires are abundant, which leaves those areas which were the cradle of successive cultural groups largely unrepresented. Sources of environmental evidence are now emerging even from this unpromising background, an important element amongst which are man's own works. The evidence of changes wrought by man may come from non-botanical as well as botanical material. Pollen, charcoal, phytoliths, seeds, mosses, and other macroscopic plant remains may be extracted, but indirect evidence may also be obtained from land snails, insects, bones (including small vertebrates), as well as from preserved soils and land surfaces. In the various environments considered a trend from forest through clearance to pastoral or arable agriculture can usually be demonstrated. These changes may ultimately result in site deterioration on a large scale, the nature of which will depend upon the ecological conditions and the practices at work. In extreme cases peat may form or soil erosion take place. On base-poor soils, soil acidification may become so intense that the land is no longer usable for traditional agriculture and is allowed to degenerate to moorland or heath. In early historic times much degraded land came into use again for hill-grazing, a process which further depauperated both the flora and the soils. [ABSTRACT FROM AUTHOR]

Reproduction was examined in one summer annual (Euphrasia pseudokerneri) and two biennials (Linum catharticum and Gentianella amarella) in chalk grassland, and three dune winter annuals (Erophila verna, Cerastium semidecandrum and Myosotic ramosissima). Gentianella was examined in 1979 to 1981 and all other species in 1980 and 1981, making a total of 13 separate datasets, Plants with one or two fruits had fewer seeds per fruit in all 13 cases. As plant size increased to six to ten fruits, seed number gradually increased. The relationship was similar in 1980 and 1981 for all six species. A 'depauperate' plant was therefore defined as one which produces significantly fewer seeds per fruit than large plants. Field populations of all species averaged less than nine fruits per plant, so that the relationship between seed number and fruit number was important in determining seeds produced per plant. Although this relationship has only been noted in three other species, I interpret five recent papers as suggesting the existence of a similar relationship between fruit number and seed number. I interpret the effect as analogous to the abortion of fruits in plants with many fruits. [ABSTRACT FROM AUTHOR]

Plant growth analysis, demographic analysis and yield component analysis are three procedures used to study relationships underlying plant growth and development. Previously, it has been shown that demographic analysis is qualitatively different from plant growth analysis. This paper demonstrates how plant growth analysis and yield component analysis can be merged into a composite procedure, sequential plant growth analysis. The composite approach treats some of the traditional indices of plant growth, including leaf area ratio, leaf area index, unit leaf rate, relative growth rate, crop growth rate and harvest index, as yield components. Regression analysis is used to assess quantitatively the contributions of individual yield components to variations in growth and yield. Fitted curves and trends in coefficients of determination are both used to follow the time course of relationships during development. A study of vegetative growth in bean plants is used to illustrate the composite procedure. [ABSTRACT FROM AUTHOR]

Methods of growing axenic seedlings infected by vesicular arbuscular mycorrhizal fungi are described, using agar, paper or glass as a support. Two of the techniques are particularly suitable for studying the interaction between the fungus and the host plant, for example the germination of the spore inoculum, hyphal growth around the roots before the symbiosis has been initiated and the early stages of root penetration. [ABSTRACT FROM AUTHOR]

Incompatibility is a common means of controlling breeding behaviour among plants, and has been an important factor in evolution. It acts to prevent self-fertilization, as well as to prevent sterilization of ovules by foreign pollen. Angiosperms have both inter- and intraspecific incompatibility, and these are controlled by the same S gene complex. Gymnosperms, however, have only interspecific incompatibility. Observations on incompatibility behaviour in flowering plants have suggested that interspecific incompatibility evolved first among gymnosperms or progymnosperms as a means of protecting their naked ovules from foreign pollen. Duplication and redifferentiation of this 'primary specificity' gene in angiosperm precursors subsequently gave rise to 'secondary specificity' controlling intraspecific incompatibility. Today there are three basic types of incompatibility found among the angiosperms: (i) inherently independent control--each allele independently expresses its individual specificity, shows allelic interaction in the pollen after S gene duplication; (ii) inherently complementary control--alleles of two or more incompatibility loci co-operate to produce a single specificity, shows no allelic interaction; and (iii) late complementary control--alleles of two or more incompatibility loci co-operate to produce a single specificity, shows allelic interaction. The pattern of distribution of these three types of control has given rise to a controversy over which represents the most primitive type of angiosperm incompatibility. The present paper examines the factors involved in secondary evolution of incompatibility, and concludes that independent control is in fact more primitive. Complementary control probably developed secondarily and independently several times during angiosperm evolution, the first occurrence. [ABSTRACT FROM AUTHOR]

The fruit of aonla (Emblica officinalis) remains at rest without growth for a period of 3½ months after setting and resumes growth thereafter. Studies on endogenous gibberellin activity of the fruit and exogenous applications of gibberellin to the fruit at rest suggest that the inability of the fruit to resume growth immediately after setting is not due to gibberellin deficiency. The fruit, when making rapid growth following its rest, contained six gibberellin-like factors active in the lettuce hypocotyl test. Five behaved like gibberellins A1, A3, A4, A7 and A9 in paper, thin-layer and silicic acid : celite column chromatography. [ABSTRACT FROM AUTHOR]

The content of gibberellin-like (GA-like) substances in various parts of young alder (Alnus glutinosa (L.) Gaertn.) plants was estimated by means of the lettuce hypocotyl bioassay. The highest levels of GA-like activity were found in the root nodules, of dormant plants, plants emerging from dormancy, and plants in full leaf. No major differences were found in the roots and leaves of nodulated as opposed to nonnodulated plants, although the stems of nodulated plants did contain lower levels of GA-like activity. The detection of seasonal changes in GA-like activity in root nodules from mature trees was dependent upon the method of chromatography employed. One major peak of biological activity was detected following paper chromatography and no large changes were detected in the level of this component. In contrast, three zones of GA-like activity could be detected after thin layer chromatography (TLC) and there were marked seasonal changes in activity in these three zones. This can be attributed either to changes in levels of the GA-like substances themselves and/or to variations in the amounts of impurities interfering with the response of the bioassay. A number of peaks of GA-like activity were detected by lettuce and rice bioassays following analysis of a large-scale extract on a preparative high performance liquid chromatograph (HPLC). However, both the total number and the identity of the substances responsible for this activity, remain to be determined. [ABSTRACT FROM AUTHOR]

The article comments on the prominence of papers featured in the "New Phytologist" journal that consider various aspects of plant interactions with the environment. The author believes that the relative change in scope can be traced back over more than a century that the journal has been published. The coordinated efforts of scientists are needed to respond to the challenges posed by atmospheric and climactic change.

The article discusses the views of the authors on a research paper about the phenotypic selection on floral traits. They emphasize that the results of the study will inspire others to make similar investigations with other model systems in pollination biology. They stress that the researchers use a logical framework in analyzing floral scent. They also assert that the paper can serve as a basis in understanding natural selection on floral scent traits.

This article presents an introduction of the special issue of the journal "New Phytologist." This Special issue of the journal explore the impacts of variation in leaf structure on processes occurring from the level of the leaf itself to that ecosystem and biomes. The introductory review by Vince Gutschick assesses the basic consequences of differences in leaf structure, and this is followed by both reviews and research papers that expand on this theme: providing up-to-date accounts of the environmental, genotypic and whole-plant controls over leaf structure.

The article introduces the journal New Phytologist. The New Phytologist founded in 1902 by researcher Arthur Tansley and now a registered charitable trust, is managed by a panel of Trustees and Advisors who receive no remuneration. Among their tasks, in addition to those of editing papers and preparing the monthly issues of the journal, are ensuring that the Trust remains on a firm financial footing and that profit from sales are used entirely to enhance the study of plants. To these ends, the Trustees and Advisors have continued actively to exploit the competition that exists in the publishing trade to obtain the best return for the outlay of subscribers.