Controlling Supply Quality and Waste in Brassica vegetables: Understanding the genetics of maturity to breed varieties in response to climate change.

Flowering is a key component of plant adaptation, affecting geographical distribution and suitability for farming practices. It is highly relevant to yield, quality and environmental considerations as flowering at the appropriate time ensures best use of the available growing season, promoting sustainability and reducing the need for inputs. The genus Brassica includes species with many morphological forms that are cultivated for use as vegetables, oils, fodder and condiments, and much of this morphological diversity can be attributed to variation in flowering time. Biennial cultivars require a period of cold treatment (vernalization) to induce flowering. This flowering behaviour is critical for the production of some vegetable forms and for adaptation to certain agricultural practices, such as planting of overwintering cauliflower varieties. Annual Brassica cultivars do not require cold treatment to flower, although some annuals can respond to vernalization by flowering earlier and more uniformly. How different varieties respond to vernalization has a big effect on when and how they mature. Many vegetables are harvested and eaten at the vegetative stage, prior to flowering. Successfully predicting the timing and length of the vegetative phase has a big influence on the quality and commercial return from the crop. For other vegetables it is the timing of the floral transition that is critical. In this project we will identify genes which can exert greater or lesser control on the vernalization process with the aim of using this information to produce parent lines and hybrids which have a more predictable harvest period. We will relate variation at these loci to performance under present and historical weather patterns to associate specific allelic combinations with maturity under different climatic conditions. Knowledge of key Brassica vernalization genes and how they vary in different vegetable Brassicas will allow us to address key questions about the impact of climate patterns on the availability of UK-produced quality Brassica vegetables.

The UK has a strong base in flowering time research, especially in the control of vernalization. From the work of Caroline Dean at the John Innes Centre, and others, much is now known about the genetic pathways regulating vernalization in the model plant Arabidopsis thaliana. Using the Genetic resources developed in Horticulture LINK project HL0186 we will identify the genes controlling vernalization in Brassica and exploit this information to develop tools to speed up the breeding in Brassica vegetable crops. We will exploit the continually expanding genomic resources in Brassica to map paralogues of key Arabidopsis genes involved in the control of flowering with a focus on known vernalization genes. We will use the most recent developments in the Dean lab to expedite this choice, together with Brassica: Arabidopsis synteny to identify putative candidates underlying QTL mapped under different temperature x time treatments. Identification of candidate genes for selected QTL will be confirmed by co-segregation of alleles with maturity phenotypes in backcross progeny. Early and late alleles of putative candidates will be transformed into appropriate Arabidopsis mutants to test complementation. We will demonstrate the generality of the findings by analysing allelic variation at these loci in current cauliflower varieties and compare this with known vernalization responses. To identify novel, functional allelic variation a wide range of germplasm will be screened at candidate gene loci including the Defra funded Diversity Fixed Foundation Sets (DFFS) for B.oleracea and the wild C genome being produced at Warwick HRI. Allelic variation at candidate loci will be related to performance under past and present weather patterns. We will use the UKCP scenarios, and in particular the Weather generator, to model future growing conditions. We will link past and current variety performance to inform future breeding strategies for continuity of production.

All UK Brassica growing areas are subject to problems caused by climate changes influencing harvest dates. Increased understanding of the vernalization process in Brassica and its effect on maturity under a range of climate scenarios will result in the breeding of varieties with a more predictable, robust response to the effect of temperature. The information learnt from this project will be directly applicable not only to Purple Sprouting Broccoli, but to other Brassica vegetable crops such as green broccoli, calabrese and cauliflower. The introduction of F1 hybrids which give more predictable maturity will help to sustain the UK market share, provide flexibility and enable the industry to better adapt to both environmental constraints and changing market demands. The proposed project presents an exceptional opportunity to expand the work begun in Horticulture LINK Feasibility study HL0186 to translate basic research on a reference species to horticulturally important crops and to address issues relating to the key cross Research Council objective: Living with environmental change. The problem of planning for a consistent supply of quality product to the supermarkets is one growers have had to face since the introduction of high quality F1 hybrids. The supermarkets require a year-round supply and growers endeavour to meet this demand from UK and imported produce. The provision of varieties with more robust response to changes in temperature should help them to plan their product supply more effectively; resulting in a more reliable supply from the UK market, which in turn should result in more stable prices and less waste caused by gluts of produce. In addition the combined analysis with climatic data should aid the breeding of new varieties to help mitigate the impact of future climate patterns on the availability of UK-produced quality Brassica vegetables. The value of the total UK Brassica vegetable crop is £330M (Defra 2007 provisional statistics). The Purple Sprouting Broccoli market is around £4M and the UK is approximately 85% self sufficient. Customer research indicates that demand for the 9 month period when it is not in good supply would equal the 3 months when it is freely available and therefore there is a big scope for improvement. The current cauliflower and green broccoli market is around £200M, and the UK is approximately 50% self sufficient (2007 Defra statistics). The aim of this project is to provide tools and information that will help growers maintain their current competitive position and to support a viable and sustainable industry that can adapt to market demands and environmental constraints. The production of Brassica vegetables for the UK market extends from Jersey in the Channel Islands to Fife in Scotland, areas exhibiting very different temperatures and day lengths. An increased understanding of the genetic control of vernalization and flowering will benefit growers throughout these areas. The results will be communicated to others through publication in refereed journals and presentations at scientific meetings and at meetings of ELSA and UK Brassica Research Community. In addition the breeding companies hold open days at which demonstration plots and staff advisers will provide information to Breeders, UK and International vegetable growers and the horticultural press.