Variation in life history contributes to reproductive success in different environments. Divergence of annual and perennial angiosperm species is an extreme example that has occurred frequently. Perennials survive for several years and restrict the duration of reproduction by cycling between vegetative growth and flowering, whereas annuals live for 1 year and flower once. We used the tribe Arab...

Recent studies have elucidated the ancient polyploid history of the Arabidopsis thaliana (Brassicaceae) genome. The studies concur that there was at least one polyploidy event occurring some 14.5 to 86 million years ago (Mya), possibly near the divergence of the Brassicaceae from its sister family, Cleomaceae. Using a comparative genomics approach, we asked whether this polyploidy event was uni...

In some species, a crucial role has been demonstrated for the seed endosperm during germination. The endosperm has been shown to integrate environmental cues with hormonal networks that underpin dormancy and seed germination, a process that involves the action of cell wall remodeling enzymes (CWREs). Here, we examine the cell wall architectures of the endosperms of two related Brassicaceae, Ara...

The Brassicaceae is a large plant family (338 genera and 3,700 species) of major scientific and economic importance. The taxonomy of this group has been plagued by convergent evolution in nearly every morphological feature used to define tribes and genera. Phylogenetic analysis of 746 nrDNA internal transcribed spacer (ITS) sequences, representing 24 of the 25 currently recognized tribes, 146 g...

Self-pollen rejection is an important reproductive regulator in flowering plants, and several different intercellular signaling systems have evolved to elicit this response. In the Brassicaceae, the self-incompatibility system is mediated by the pollen S-locus Cys-Rich/S-locus Protein11 (SCR/SP11) ligand and the pistil S Receptor Kinase (SRK). While the SCR/SP11-SRK recognition system has been ...

crops include oil crops, vegetables, condi-ments, fodder crops, and ornamental plants. Most of these crops belong to or are closely related to the genus Brassica. The Brassicaceae also includes the most intensively studied model plant, Arabidopsis thaliana. In molecular genetic studies of Brassicaceae crops, information on A. thaliana genes is highly useful, and many genes important for plant b...

xix Introduction 1 0.1 Genomic approaches in the study of plant evolution . . . . . . . . . . 1 0.2 Why study gene duplication? . . . . . . . . . . . . . . . . . . . . . . 2 0.3 Duplication of genes of secondary metabolism . . . . . . . . . . . . . 4 0.4 The biological role of tropinone reductases in Solanaceae . . . . . . . 5 0.5 Tropinone reductases in Brassicaceae . . . . . . . . . . . . . ....

BACKGROUND Pollen-pistil interactions are an essential prelude to fertilization in angiosperms and determine compatibility/incompatibility. Pollen-pistil interactions have been studied at a molecular and cellular level in relatively few families. Self-incompatibility (SI) is the best understood pollen-pistil interaction at a molecular level where three different molecular mechanisms have been i...