COMPARATIVE BIOSYNTHETIC PATHWAYS IN HIGHER PLANTS

ABSTRACT During the last ten years or so, variation in secondary plant products between different taxa has been increasingly used in systematic and evolutionary studies. However successful this approach has been, it now needs to be tempered by a consideration of the underlying variation in the biosynthetic pathways leading to the compounds in question. In some cases cognate compounds are formed by two or more pathways in different taxa; in others the same biosynthetic route is regulated in different ways. It is necessary, therefore, to examine the ontogeny and characteristics of the individual enzymes involved. Examples of such approaches are given for a large number of different classes of compound. including naphthoquinones, flavonoids, rneta-carhoxv aromatic amino acids, branched chain sugars and lignin. INTRODUCTION The contribution which the investigation of biosynthetic pathways can make to the study of evolution and systematics can be divided into three main areas: (a) the elucidation of general biosynthetic patterns by tracer techniques; (b) comparative biochemistry of individual biosynthetic steps and of the enzymes involved; and (c) comparative biochemistry of regulatory systems

Domestication Syndrome in Caimito (Chrysophyllum cainito L.): Fruit and Seed Characteristics

Domestication Syndrome in Caimito (Chrysophyllum cainitoL.): Fruit and Seed Characteristics: The process of domestication is understudied and poorly known for many tropical fruit tree crops. The star apple or caimito tree (Chrysophyllum cainito L., Sapotaceae) is cultivated throughout the New World tropics for its edible fruits. We studied this species in central Panama, where it grows wild in tropical moist forests and is also commonly cultivated in backyard gardens. Using fruits collected over two harvest seasons, we tested the hypothesis that cultivated individuals of C. cainito show distinctive fruit and seed characteristics associated with domestication relative to wild types. We found that cultivated fruits were significantly and substantially larger and allocated more to pulp and less to exocarp than wild fruits. The pulp of cultivated fruits was less acidic; also, the pulp had lower concentrations of phenolics and higher concentrations of sugar. The seeds were larger and more numerous and were less defended with phenolics in cultivated than in wild fruits. Discriminant Analysis showed that, among the many significant differences, fruit size and sugar concentration drove the great majority of the variance distinguishing wild from cultivated classes. Variance of pulp phenolics among individuals was significantly higher among wild trees than among cultivated trees, while variance of fruit mass and seed number was significantly higher among cultivated trees. Most traits showed strong correlations between years. Overall, we found a clear signature of a domestication syndrome in the fruits of cultivated caimito in Panama

Mediterranean-climate streams and rivers: geographically separated but ecologically comparable freshwater systems

Streams and rivers in mediterranean-climate regions (med-rivers in med-regions) are ecologically unique, with flow regimes reflecting precipitation patterns. Although timing of drying and flooding is predictable, seasonal and annual intensity of these events is not. Sequential flooding and drying, coupled with anthropogenic influences make these med-rivers among the most stressed riverine habitat worldwide. Med-rivers are hotspots for biodiversity in all med-regions. Species in med-rivers require different, often opposing adaptive mechanisms to survive drought and flood conditions or recover from them. Thus, metacommunities undergo seasonal differences, reflecting cycles of river fragmentation and connectivity, which also affect ecosystem functioning. River conservation and management is challenging, and trade-offs between environmental and human uses are complex, especially under future climate change scenarios. This overview of a Special Issue on med-rivers synthesizes information presented in 21 articles covering the five med-regions worldwide: Mediterranean Basin, coastal California, central Chile, Cape region of South Africa, and southwest and southern Australia. Research programs to increase basic knowledge in less-developed med-regions should be prioritized to achieve increased abilities to better manage med-rivers

Reise durch Rumelien und nach Brussa im Jahre 1839 von H.Grisebach, Dr. med.

Preface: Grisebach, H.Dedication:Pagination: PP6+361P+1PPText Genre:Pros