Smart breeding for salad rocket

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'Salad' rocket is among the most nutritious of leafy vegetables, but concentrations of health beneficial compounds and the taste of leaves is highly variable. Numerous factors are known to influence these attributes in rocket, but very little technical research has been conducted to improve the consistency and perceived 'quality' of leaves. One of the biggest complaints from industrial processors and retailers is this inconsistency throughout the year and between growing regions. A great deal has been learned about what different consumers like or dislike in current rocket varieties. Some people prefer bitter and pungent leaves, whereas others prefer mild and sweet. By utilising this knowledge, and combining it with genetic and chemical information, we are proposing to provide tools for breeding rocket for increased consumer acceptance, increased nutritional density, and increased stability across growing regions. We also aim to produce resources that will allow plant breeders to select varieties with a signature taste and flavour profile that is acceptable to consumers, while maintaining the maximum health benefits associated with the crop. Previous work at the University of Reading, in collaboration with Elsoms Seeds (a commercial seed merchant and plant breeding company) and Bakkavor (a company composed of international growers, processors and distributors of rocket), has produced a large amount of information relating to the chemical and sensory profiles of rocket. Genomic research into rocket species however, is almost non-existent, and in order to progress the crop significantly these will need to be established. The world's first genomic sequencing of rocket is set to commence before the end of 2015, and conclude Spring 2016. This information will allow us to identify specific 'markers' within the genetic code that can be used to identify rocket plants with specific attributes, such as bitterness, sweetness, or hotness, for example. It will also allow us to identify regions of the genetic code that are heavily associated with health beneficial chemicals, such as glucosinolates. By examining many hundreds of these genetic 'markers' across different growing locations (the UK and Italy), climatic conditions (field and controlled environment), and the whole supply chain, it is possible to create a set of 'markers' for each respective circumstance that will inform us about a plant's propensity to conform to a desired set of attributes. By tracking these 'markers' from one generation of plants to the next it is then possible for the breeder to select plants containing these markers and eventually cross-pollinate them with other promising individuals to develop new varieties.At specific points in the project (e.g. during field experiments, and industrial processing trials) chemical components will be evaluated. Our primary focus is on glucosinolates; a type of compound that produces health beneficial chemicals called isothiocyanates. Consumption of these has been consistently linked with reduced risk of developing certain types of cancer and reduced incidence of cardiovascular disease. They also produce the distinctive hotness of rocket leaves. We are also interested in looking at sugar and amino acid contents of leaves. Not only do these influence taste, but they are also the building blocks of glucosinolate molecules. Through understanding the genetics of each compound's synthesis, we can highlight specific 'marker' profiles that will give a desired sensory profile. We can also identify markers that are adverse to the desired sensory profile and de-select plants to ensure that they do not persist within future populations.The genetic resources created at the end of this project will go on to inform selections within the active rocket breeding program at Elsoms Seeds. Ultimately this will create new commercial varieties that have consistent and superior sensory and nutritional qualities compared to existing ones.