Principles and practices of plant genomics. Volume 2: Molecular breeding

Abstract

This volume is part of the two-book series Principles and practices of plant genomics edited by Kole and Abbott, which draws an updated picture of the most recent advances in plant genomics and their direct applications in plant breeding. The book is divided into 13 chapters, supplemented by an exhaustive list of abbreviations and a useful index. Contributions from multiple authors, all experts in their fields, lead to some redundancy from one chapter to another, but the overlap usually appears appropriate and enhances the readability of individual chapters. Chapter 1 is devoted to the theory of marker-assisted selection (MAS), with a summary of the basic principles and concepts of the QTL mapping approach (as a transition from Volume 1: Genome mapping; see review in Annals of Botany 102: 879–880, 2008) followed by a detailed description of the theoretical aspects of various MAS strategies, with their advantages and disadvantages depicted from the breeder's point of view. Chapter 1 ends with a discussion of the feasibility and efficiency of candidate-gene approaches as well as the possibility to characterize expression QTLs (eQTLs) with the recent development of technical platforms dedicated to gene expression. Chapter 2 reviews the use of molecular markers in germplasm conservation, from the acquisition and preservation of plant genetic resources to their evaluation and utilization, with relevant examples from various plant species. Association-mapping is only briefly described at the end of this chapter, but is documented in Chapter 3 as a means to dissect the genetics of complex traits such as yield, and also illustrated in Chapter 8 with its application in fruit-tree breeding. However, it is a cause of regret that association-mapping is dispersed throughout different chapters, as it would have been appropriate to dedicate an entire chapter to this newly expanding domain – this would have strongly contributed to the originality of the present book following the publication of Newbury's volume Plant molecular breeding (2003) and Lorz and Wenzel's Molecular marker systems in plant breeding and crop improvement (2007). Chapters 3 to 7 are dedicated to the applications of molecular markers in breeding crops for complex agronomic traits, namely yield and yield-related traits, quality (e.g. nutritional value, flavour, oil content, processing qualities), biotic and abiotic stress resistance, and physiological traits (e.g. photosynthetic capacity, flowering, nitrogen fixation), respectively. Chapters 8 to 11 are devoted to specific plant groups (fruit crops, forest trees, polyploid crops, forage and turf plants), emphasizing their specific breeding requirements. All these chapters are illustrated with many concrete examples from numerous crop plants, making the concepts easier to understand. Of particular interest is the very complete Chapter 9 dealing with molecular mapping and breeding in forest trees. The chapter starts by summarizing the domestication and selection history of forest trees, and reviewing the current ex situ and in situ conservation strategies with the specific challenges of tree germplasm conservation. Then the author depicts (1) the advances in structural genomics of forest trees, including the full sequencing of the poplar genome, and (2) the specificities and application domains of genetic and physical mapping in trees that allow (3) trait mapping; this last part emphasizes the role of functional genomics for gene discovery. The author demonstrates successfully that such an integrative approach ensures the efficiency of modern molecular breeding in a species that requires approximately two decades for a traditional breeding cycle. Considering that all plant species have a polyploid origin, another important chapter is the more theoretical Chapter 10, which addresses the molecular breeding principles of a polyploid crop plant by taking the case of an autotetraploid species (using potato and alfalfa as examples) and generalizes the theory to allopolyploid and segmental allopolyploid species. Finally, I can only regret that Chapter 5, on molecular mapping and breeding for biotic stress resistance, lingers too much over the description of well-established molecular markers and the theory of the different existing MAS strategies, using soybean breeding as the sole example, instead of providing an up-to-date summary of the recent advances illustrated by concrete applications in this field. In contrast, Chapter 6 provides a very well-documented review on the advances made in molecular mapping and breeding for abiotic stress resistance. First, the authors recall the genetic principles of QTL mapping to be considered when analysing abiotic stress (heritability, genotype × environment interaction, experimental design), and then comment extensively on numerous examples from a variety of crops for the main abiotic stresses, namely drought, salinity, nutrient stress, low temperature stress, and their different components. The two last chapters deal with, respectively, plant genetic engineering and intellectual property rights concerning plant material in general, and more specifically innovations in agriculture; these two topics being increasingly closely related with the development of molecular breeding. Chapter 12 starts with a summary of the theories and concepts of plant genetic manipulation; some illustrative figures for the different technical and molecular aspects described in the text would have been useful to the reader. The authors then give a short but objective picture of the advances made in plant breeding with this technology by reviewing, for several plant crops, the main traits that have been modified by genetic manipulation. This chapter would have gained in interest by providing some figures or tables with economic data, for instance concerning the global area for genetically modified crops (by crop, by country, by trait … ) and their tendencies. Chapter 13 is well written and depicts clearly the current international legislative context and the different available types of protection for innovations in modern plant breeding, which represents an increasingly thought-provoking domain as the ‘gene revolution’ progresses. Most of the chapters are suited for undergraduate students who are interested in connecting molecular markers to plant breeding, and I recommend this book to postgraduate students, teachers and advanced researchers for whom it will constitute a valuable summary of all the recent advances made in the field, as well as providing a source of references to go more deeply into specific areas of plant molecular breeding.