Anthocyanins are secondary metabolites found in higher plants that contribute to the colors of flowers and fruits. In apples (Malus domestica Borkh.), several steps of the anthocyanin pathway are coordinately regulated, suggesting control by common transcription factors. A gene encoding an R2R3 MYB transcription factor was isolated from apple (cv Cripps' Pink) and designated MdMYB1. Analysis of the deduced amino acid sequence suggests that this gene encodes an ortholog of anthocyanin regulators in other plants. The expression of MdMYB1 in both Arabidopsis (Arabidopsis thaliana) plants and cultured grape cells induced the ectopic synthesis of anthocyanin. In the grape (Vitis vinifera) cells MdMYB1 stimulated transcription from the promoters of two apple genes encoding anthocyanin biosynthetic enzymes. In ripening apple fruit the transcription of MdMYB1 was correlated with anthocyanin synthesis in red skin sectors of fruit. When dark-grown fruit were exposed to sunlight, MdMYB1 transcript levels increased over several days, correlating with anthocyanin synthesis in the skin. MdMYB1 gene transcripts were more abundant in red skin apple cultivars compared to non-red skin cultivars. Several polymorphisms were identified in the promoter of MdMYB1. A derived cleaved amplified polymorphic sequence marker designed to one of these polymorphisms segregated with the inheritance of skin color in progeny from a cross of an unnamed red skin selection (a sibling of Cripps' Pink) and the non-red skin cultivar Golden Delicious. We conclude that MdMYB1 coordinately regulates genes in the anthocyanin pathway and the expression level of this regulator is the genetic basis for apple skin color.

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Light-induced expression of a MYB gene regulates anthocyanin biosynthesis in red apples.

In an age of accelerating biodiversity loss, this timely and critical volume summarizes recent advances in biodiversity-ecosystem functioning research and explores the economics of biodiversity and ecosystem services. The book starts by summarizing the development of the basic science and provides a meta-analysis that quantitatively tests several biodiversity and ecosystem functioning hypotheses. It then describes the natural science foundations of biodiversity and ecosystem functioning research including: quantifying functional diversity, the development of the field into a predictive science, the effects of stability and complexity, methods to quantify mechanisms by which diversity affects functioning, the importance of trophic structure, microbial ecology, and spatial dynamics. Finally, the book takes research on biodiversity and ecosystem functioning further than it has ever gone into the human dimension, describing the most pressing environmental challenges that face humanity and the effects of diversity on: climate change mitigation, restoration of degraded habitats, managed ecosystems, pollination, disease, and biological invasions.However, what makes this volume truly unique are the chapters that consider the economic perspective. These include a synthesis of the economics of ecosystem services and biodiversity, and the options open to policy-makers to address the failure of markets to account for the loss of ecosystem services; an examination of the challenges of valuing ecosystem services and, hence, to understanding the human consequences of decisions that neglect these services; and an examination of the ways in which economists are currently incorporating biodiversity and ecosystem functioning research into decision models for the conservation and management of biodiversity. A final section describes new advances in ecoinformatics that will help transform this field into a globally predictive science, and summarizes the advancements and future directions of the field. The ultimate conclusion is that biodiversity is an essential element of any strategy for sustainable development.

Biodiversity, Ecosystem Functioning, and Human Wellbeing: An Ecological and Economic Perspective

In mammals, cadmium is widely considered as a non-genotoxic carcinogen acting through a methylation-dependent epigenetic mechanism. Here, the effects of Cd treatment on the DNA methylation patten are examined together with its effect on chromatin reconfiguration in Posidonia oceanica. DNA methylation level and pattern were analysed in actively growing organs, under short- (6 h) and long- (2 d or 4 d) term and low (10 mM) and high (50 mM) doses of Cd, through a Methylation-Sensitive Amplification Polymorphism technique and an immunocytological approach, respectively. The expression of one member of the CHROMOMETHYLASE (CMT) family, a DNA methyltransferase, was also assessed by qRT-PCR. Nuclear chromatin ultrastructure was investigated by transmission electron microscopy. Cd treatment induced a DNA hypermethylation, as well as an up-regulation of CMT, indicating that de novo methylation did indeed occur. Moreover, a high dose of Cd led to a progressive heterochromatinization of interphase nuclei and apoptotic figures were also observed after long-term treatment. The data demonstrate that Cd perturbs the DNA methylation status through the involvement of a specific methyltransferase. Such changes are linked to nuclear chromatin reconfiguration likely to establish a new balance of expressed/repressed chromatin. Overall, the data show an epigenetic basis to the mechanism underlying Cd toxicity in plants.

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In Posidonia oceanica cadmium induces changes in DNA methylation and chromatin patterning

Dormancy in temperate fruit trees in a global warming context: A review

The intention of this review is to discuss floral initiation of horticultural trees. Floral initiation is best understood for herbaceous species, especially at the molecular level, so a brief overview of the control of floral initiation of Arabidopsis (Arabidopsis thaliana (L.) Heynh.) precedes the discussion of trees. Four major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod and temperature, autonomous floral initiation, and regulation by gibberellins. Tropical trees are generally induced to flower through environmental cues, whereas floral initiation of temperate deciduous trees is often autonomous. In the tropical evergreen tree mango, Mangifera indica L., cool temperature is the only factor known to induce flowering, but does not ensure floral initiation will occur because there are important interactions with vegetative growth. The temperate deciduous tree apple, Malus domestica Borkh., flowers autonomously, with floral initiation dependent on aspects of vegetative development in the growing season before anthesis, although with respect to the floral initiation of trees in general: the effect of the environment, interactions with vegetative growth, the roles of plant growth regulators and carbohydrates, and recent advances in molecular biology, are discussed.

/pdf/regulation-of-floral-initiation-in-horticultural-trees-59ru41w9yz.pdf

Regulation of floral initiation in horticultural trees

SummaryCalyx cracking in ‘Pink Lady’ apple (Malus × domestica Borkh.) results in substantial economic losses. ‘Pink Lady’ apple trees were sprayed with various rates and combinations of synthetic gibberellins (GA3, or GA4 plus GA7) and a synthetic cytokinin (6-benzyladenine; BA) at different phenological stages, starting at 60 d after full bloom (DAFB) until 150 DAFB, to determine if the incidence of cracking could be reduced. The experiments were conducted in Northern Israel between 2008 – 2011. The percentages of fruit with calyx cracking decreased following three applications of 0.2% (v/v) Superlon™ (i.e., 40 mg l–1 BA plus 40 mg l–1 GA4+7) at 14 d intervals, starting at 60 DAFB.GA3 or GA4+7 alone had no effect on cracking. In addition, the Superlon™ treatments resulted in increases in epidermal cell density at the calyx end, which may have contributed to the increased elasticity of the peel, thus preventing crack formation. No change was observed in cuticle thickness. Fruit quality was not affected by...

Reducing the incidence of calyx cracking in ‘Pink Lady’ apple using a combination of cytokinin (6-benzyladenine) and gibberellins (GA4+7)

SummaryThe effects of post-harvest water stress on the productivity of ‘Spadona’ pear in the subsequent season and on autumnal bloom were studied in field-grown mid-season pear. Two factors were ex...

Effects of post-harvest water stress on autumnal bloom and subsequent-season productivity in mid-season ‘Spadona’ pear

SummaryFinal fruit size in pear depends on the combined contributions of the number of cells present at fruit-set, the number of subsequent cell divisions, and on cell expansion. To date, in spite of the commercial application of cytokinins to induce larger fruits, no detailed studies have addressed the question of how cytokinin signalling and cell division regulate fruit growth under field conditions. As previously reported, ‘Spadona’ pear fruits treated once with N(2-chloro-4-pyridyl)-N’-phenylurea (CPPU) or N-phenyl-N’-1,2,3-thiadiazol-5-ylurea (TDZ) showed a significant increase in size compared to untreated fruit. Here we monitored the effect of CPPU and TDZ treatments on the number and size of parenchyma cells and stone cells in fruit pulp. Application of both synthetic cytokinins on 10 mmsized fruitlets had no effect on the size or number of stone cells during fruit development. However, the parenchyma that forms the fruit flesh, between the epidermis and the seed layers, had significantly smaller ...

Synthetic cytokinins extend the phase of division of parenchyma cells in developing pear (Pyrus communis L.) fruits

SummaryThe European pear (Pyrus communis) cultivars ‘Spadona’ and ‘Coscia’ exhibit full self-incompatibility, and therefore fruit production depends entirely on cross-pollination, which is carried out mainly by honeybees (HB), the ultimate pollinators of pear. To increase the efficiency of HB pollination, colony numbers are doubled or introduced sequentially; nevertheless, yields remain relatively low and fruit are small due to the low number of seeds per fruit. In the present research, we studied the effect of adding bumblebees (BB) to the HB colonies. Adding BB hives to pear orchards 10 d before bloom, at a density of ten hives ha–1, improved the percentage fruit-set, fruit size, and also sometimes, fruit yield. These positive results were due to a large increase in seed numbers per fruit, especially in ‘Spadona’ which had only one-to-three seeds per fruit when pollinated only by HB, compared to four-to-six seeds after pollination with HB + BB. There was a strong positive correlation between the number ...

Adding bumblebees (Bombus terrestris L., Hymenoptera: Apidae) to pear orchards increases seed number per fruit, fruit set, fruit size and yield

Summary‘Golden Delicious’ is one of the main apple cultivars in the world. Apple is a member of the Rosaceae family that harbours the gametophytic self-incompatible fertilization system. The potency of self-incompatibility may vary, depending on the level of rejection of the self-fertilization. Defining the level of self-pollen rejectionhas great horticulture importance since low potency of self-fertilization or total self-pollen rejection result in yield reduction. ‘Golden Delicious’ is considered self-compatible. In this study the potency of the self-fertilization ability of ‘Golden Delicious’ was determined. By implementing PCR-S-allele analysis, self and non-self-fertilization cases were distinguished and accurate self-fertilization levels were identified. From the results, it is apparent that ‘Golden Delicious’ has a very low potency of self-fertilization.

Raphael A. Stern

Papers

Reducing the incidence of calyx cracking in ‘Pink Lady’ apple using a combination of cytokinin (6-benzyladenine) and gibberellins (GA4+7)

Effects of post-harvest water stress on autumnal bloom and subsequent-season productivity in mid-season ‘Spadona’ pear

Synthetic cytokinins extend the phase of division of parenchyma cells in developing pear (Pyrus communis L.) fruits

Adding bumblebees (Bombus terrestris L., Hymenoptera: Apidae) to pear orchards increases seed number per fruit, fruit set, fruit size and yield

Determination of the self-fertilization potency of ‘Golden Delicious’ apple