Genetics, Genomics and Breeding of Berries PDF

Preface to the Volume

The commercial berry has enjoyed a resurgence of interest over the last decade, mostly due to the promotion of its potentially positive health benefits. Recent discussions have implicated berries in the possible mitigation of aging, cancer, brain function, cardiovascular disease and metabolic disorders. Colorful and flavorful berries are capsules filled with antioxidants, anthocyanins, polyphenols and ellagic acid—all compounds with possible roles in disease prevention or enhanced quality of life. Berries occupy a distinct dietary role in highly industrialized nations. As mundane causes of mortality are overcome with new medical technology humans are living longer, and the trends predict higher likelihoods of long-term degenerative disease leading to death. Diets rich in fruits and vegetables will have a central role in limiting or preventing these illnesses, if not for their inherent compounds then for their intense flavors and colors with few accompanying calories. In the developing world berries might deliver nutritious compounds to those who desperately need them- possibly via plants that will be adapted to local conditions. The popularity and demand for berries continues to increase.

At the same time the production of all fruits, nuts and vegetables is limited by a series of challenges. Once potent soil fumigants have been banned, no longer presenting an affordable and effective way to curb soil pests, pathogens and weedy competitors. The price of labor, fuel, and fertilizers continues to rise, while prime land and fresh water become increasingly scarce. Farmers have to do more with less, and then do so in a market where prices are depressed by a limited number of competitive wholesalers. The current slate of commercial cultivars meets the berry demand, but as consumption grows in concert with production threats, new cultivars will need to be developed to meet the challenges of production and distribution.

Today, the challenge is to enhance varietal performance and produce perfect products with fewer agricultural inputs. These accomplishments must be performed with high sensitivity to environmental stewardship yet be flexible in an ever-changing climate. Traditional crop breeding offers the potential to greatly improve the capacity of cultivars. Coupled with modern genomics-enabled breeding techniques, the likelihood for breeding programs to deliver better products faster only increases. Plant breeding has always been as much as an art as it is science, and now the effective staples of genetics and selection find new partnership with high-throughput information capture and in planta validation.

The central challenge of the post-genomics era will be to marry copious genetic information to the breeding task, to sculpt it into productive channels that will drive the efficient production of higher-quality fruits. This book explores the state of the art of berry genomics, genetics and breeding and provides some hints as to how these technologies can assist, or in some cases have assisted, in berry improvement.

In order to best define the scope of this text it is important to examine some definitions and delineate what is and what is not a berry in the parlance of this work. A botanist will maintain strict adherence to a textbook definition where a berry is a simple fruit containing seeds produced from a single ovary. Some examples of true botanical berries are tomatoes, plantains, eggplants, grapes, persimmons, loquats and peppers. A strictly botanical analysis of the table of contents will reveal that this book is not really about berries at all, but instead is a text on epigynous, aggregate and accessory fruits. While botanically accurate, such descriptions create a cognitive disconnect from the spirit and intent of this work and hardly make for a compelling title. This text is about the berry of the familiar vernacular, the small, flavorful and nutritious plant-borne foods, rich in sugars and healthful compounds.

Another contradiction: Many true berries certainly do reside within the pervue of this strictly botanical definition. True berries, such as currants and gooseberries (Ribes sp.), elderberries (Sambucus sp.) or mulberries (Morus sp.) are small flavorful fruits, also ascending to similar superfood status. Recent advances in currant breeding have greatly increased the size of the berry and yield of this crop. Breeding of white and black mulberries is an important venture in many parts of the world, again with measurable gains and outstanding products. Unfortunately, these true berries are represented by only skim treatment with genetic, molecular or genomic tools. The mission is a text on the genetics and genomics of berries, but with no genomics coverage in most berry species, the work is forced to explore the growing data in the small fruits most commonly thought of as berries.

For the purposes of this text berries will be discussed in the most familiar sense, examining the advances in genetics and genomics of small, soft fruits. The subjects are a small set of species from the Ericaceae and Rosaceae that have enjoyed description and improvement through use of molecular and/or genomics tools. The work is weighted certainly to the species that have benefitted from the application of genomics tools. Strawberry (Fragaria spp.) has been an increasingly attractive system for genomics-level analyses in the last decade. There is relatively more information, so the chapter has been divided into three independent sections that each stand alone and benefit from encapsulation. Blueberries and cranberries are described in stand-alone chapters while Rubus species (blackberries and raspberries) are covered in a common chapter.

To conclude, this text on berries is paradoxically not about true berries at all, but instead is about a suite of valued plant products that are central to regional economies, human health and consumer choice. The genomics and post-genomics opportunities have only begun to manifest themselves in these species, and this text marks a stepping-off point for the inevitable gains soon to be realized. Outstanding traditionally-bred resources, a rich history of physiology and pathology, and a substantial body of work in production and post-harvest technology present many areas of genomics ingress, enabling another level of analyses to synergize with existing knowledge to accelerate the development of new germplasm. The confluence of technologies will inevitably lead to new plant products, but also new paradigms in biological processes yet to be discovered.