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Manipulation of shoot branching behaviour in woody plants - HH3731SHN

A uniform framework of branches is a crucial element of plant quality in a wide range of horticultural sectors. In the hardy nursery stock industry (HNS) (valued at £434m in 2003), achieving consistency of plant form is central to improving the quality and reducing the variability of crops. However, there are many HNS species where adequate branching can be difficult to achieve and poor or non-uniform branch development currently limits economic gain. Whilst the shape of a plant is largely set by its genotype, management techniques such as pruning can be used to stimulate branching and increase the aesthetic appeal and value of the crop. Although pruning is a crucial part of the production process, the variable response of many species to pruning often reduces, rather than improves, uniformity within the crop. Improvements in batch uniformity may be achieved by grading of plants with respect to branching quality during production and by chemical applications but these can only be short-term solutions. Both pruning and grading are time consuming and, therefore, expensive and place considerable demands on an industry where skilled labour is in short supply. Despite its enormous commercial importance, the factors that underpin branching behaviour in woody perennials are not yet known. Therefore, the main objective of this project is to identify the root- and shoot-sourced chemical signals that interact to control the outgrowth of axillary and adventitious buds in woody perennials. We will use root manipulation techniques to enhance the outgrowth potential of buds of important HNS crops (e.g. Rosa, Cotinus, Forsythia). Non-invasive techniques will be used to detect the 'real time' changes in hormone profile that occur within the buds as they undergo the transition from dormancy to sustained growth. The root-sourced signals that regulate the branching response to root manipulation will be identified in xylem sap using state-of-the-art GC-TOFMS and nanoLC-MS-MS. Potentially novel signals will be detected using metabolic profiling. Informative microsatellite markers will be identified in Rosa and progenies segregating for branching potential will be raised to allow this character to be mapped to aid future work on the genetic improvement of HNS. Approaches and resources developed in previous and current Defra- and HDC-funded projects will be used to quantify how root- and shoot-sourced hormonal signals interact to control the outgrowth of axillary and adventitious buds. The collaboration with Dr Colin Turnbull (Imperial College at Wye) will provide an opportunity to incorporate resources and findings from basic research on the regulation of shoot branching patterns into this strategic research programme. This project will also provide strategic underpinning for the proposed follow-on project to HNS 117 (submitted to HDC). Also, our direct contact with nurserymen and our programme of applied research sponsored by the HDC will provide important interactions to ensure relevance of our work and communication of progress and results. This proposal will assist Defra in meeting the objectives within ROAME A HH36 'Sustainable Use of Natural Resource & Labour' and HH37 'Adaptable supply of quality fruit and vegetables and ornamentals.' Specifically, the project delivers to:1) science objectives listed in ROAME A HH36, that include an understanding of key physiological processes.2) science objectives listed in ROAME A HH37, that include improved quality and scheduling.3) technology and knowledge transfer objectives listed in ROAME A HH38 to ensure that the results of Defra's horticulture R&D programmes are available to, and used by, growers.Improving our understanding of bud development in young plants will provide a scientific rationale for the pruning regimes used on commercial nurseries. This will provide opportunities to control the variables that influence uneven bud development and outgrowth and to optimise the time of pruning relative to vegetative development. Deliverables to the industry will include reduced frequency of pruning and associated labour inputs, reduced wastage with more plants reaching the required quality and possibilities for more effective crop scheduling. These highlighted deliverables are all consistent with Defra’s policies on economic, social and environmental sustainability.
1) To devise an experimental model system for the study of the control of axillary bud outgrowth in woody plants based on commercially relevant HNS species.2) To modify the shoot’s propensity to develop branches by manipulating the rhizosphere and/or the photoperiod. 3) To identify putative root-and shoot-sourced chemical signals that stimulate axillary bud outgrowth. 4) To test the causal status of putative root- and shoot sourced signals in the regulation of bud axillary outgrowth.5) To develop microsatellite markers for Rosa, and raise segregating progenies to aid future marker-assisted selection of HNS.6) To communicate the results of this study to the grower and academic communities and to facilitate effective technology transfer to the horticultural industry.
Project Documents
• Final Report : Manipulation of shoot branching behaviour in woody plants   (1448k)
Time-Scale and Cost
From: 2005

To: 2009

Cost: £570,614
Contractor / Funded Organisations
East Malling Research
Allocated - EMR              
Hardy Nursery Stock              
Rural Communities              
Sustainable Farming and Food              
Sustainable Production              
Fields of Study