Apomixis takes centre stage

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The Flowering of Apomixis: from Mechanisms to Genetic Engineeringedited by Y. Savidan, J. Carman and T. Dresselhaus, CIMMYT Publications, Houston, TX, USA, 2001. US$25.00 pbk (xii + 243 pages)ISBN 970 648 074 9Apomixis is a fascinating mode of plant reproduction whereby seeds form asexually. Apomixis and sexual reproduction share a common cast of players because the reproductive organs of the flower are involved. However, in apomixis the scene of action is set exclusively inside the ovule. Although there are many versions of apomixis, the play is always shorter than the sexual version because key acts that feature in sexual reproduction are omitted during apomixis. For example, the embryo sac and the cells within it form directly by mitosis and meiosis is bypassed. The female role dominates in apomixis and the male is relegated to a bit-part because fertilization is not required for embryo formation. The progeny of apomicts are therefore genetic clones of the mother. Whereas, in the majority of apomictic species, the cameo role of the male is crucial for the formation of the endosperm compartment of the seed.Apomixis was discovered in the late 1800s. Mendel unwittingly worked with apomictic Hieracium species that produced progeny that completely contradicted his model about the nature of inheritance. The glorious images of the floral capitula of Hieracium on the front cover of The Flowering of Apomixis: from Mechanisms to Genetic Engineering edited by Yves Savidan, John Carman and Thomas Dresselhaus reflect the painstaking work of C.H. Ostenfeld in 1910 on the inheritance of apomixis in this plant. At this time, apomixis was an accepted phenomenon and for many years afterwards the research path became descriptive as the extent of apomixis was explored in angiosperms. Since then, several books have been written concerning the complex mechanisms that have been uncovered, but this book refreshingly reflects the current status of the field as those involved in it strive to understand the molecular basis for apomixis.Why the interest? Apomixis is not prevalent in agricultural crops but its capacity to fix a genotype and therefore hybrid vigour has significant economic advantages for agriculture if the trait can be efficiently controlled. There are arguments for traditional breeding in addition to molecularly engineering the trait in sexual plants. This theme is covered in the book. Emphasis is also placed upon the genetic analysis of apomixis, new model systems to facilitate molecular research, the developmental biology of apomixis and its relationship to sexuality, screening procedures to identify apomicts, mutagenesis approaches in sexual and apomictic plants to identify the components of apomixis and some thought provoking models on how apomixis might work. Comment is made on the protection of intellectual property to ensure that apomixis technology is made available to those that cannot afford to pay for it in addition to those that can. These topics reflect the state of the field as being one of exciting transition. The contributions from noteworthy scientists working with apomictic plants and sexual model species show that the research is moving forward because molecular techniques are being applied in combination with genetics and histology to understand apomixis in a holistic manner. The book does not solve the puzzle of apomixis but it moves the drama from a successful, long playing theatre production out into the multimedia, secure in the knowledge that the truth is out there–and tangible.