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Genetic analysis of root traits relevant to water-use in horticultural crops - HH3615SPC

The purpose of this work is to provide molecular markers that will facilitate genetic improvement of water use traits in the target crop, potato. The work is directed at root traits important for capture of soil water under conditions of limited water availability and towards root-shoot signalling processes that influence sensitivity of crop yield to irrigation. Yield and quality gains make irrigation a practical and economic option in many field crops in the UK. Irrigated land areas for vegetables and potatoes have risen steadily by 2.9-fold between 1982 and 2001, and the volume of water applied has risen by 4.7-fold [1]. However, the cost and availability of water for agriculture is likely to become increasingly restrictive in the coming years due to the recent implementation of the Water Bill (Feb 2003), and as a result of climate change in the medium to long term. Implementation of the Water Bill is expected to lead to increasing competition for water resources between agricultural, industrial and domestic users, and abstraction charges may make irrigation and therefore crop production increasingly uneconomic. Scenarios for climate change in the UK, due to greenhouse gas emissions [2], indicate that winters will become wetter, but that summers will become drier. Potato is an important field crop covering 166,000 hectares in the UK, with a value of £600 million per annum, and whose yield is particularly sensitive to drought [3]. Consequently, over half of the irrigation water in England is applied to potato [1]. If global climate change scenarios are realized there would be a massive impact on agricultural practices and the rural economies of the south and east, and crop yields could only be maintained by increasing irrigation, and/or by the development of crop varieties suited to the drier summers. There is therefore a need to develop crop varieties, particularly potato varieties, which make more efficient use of water. This addresses the DEFRA policy objective to develop horticultural production systems which use natural resources in a sustainable manner. There is a widely held view that the drought sensitivity of potato may largely be attributed to a shallow root system [4] that is not optimal for rain-fed, low input systems because of the failure to capture water and nutrients at depth. Consequently these valuable resources are often lost through drainage to local water courses, leading to inefficient water use and eutrophication. In the future, sustainable production and organic production are likely to be favoured, with reductions in nutrient inputs becoming increasingly desirable and water resources more scarce. Under these circumstances a larger, deeper root system will be required to maximise capture of water and nutrients from the soil. In recent years progress has been made in the genetic analysis of root traits in cereals, particularly rice [8-11], but little work has been done on the genetic control of root traits in non-cereal field crops. We aim to use new resources in genetics and genomics to investigate the genetic control of rooting depth and soil penetration in a Solanaceous model crop species to provide a strategic approach aimed towards future development of potato varieties more suited to water-limited, low-input environments. Root-shoot signals detect small changes in soil water content and cause reductions in leaf expansion and transpiration prior to development of water deficit in the shoot. This mechanism has evolved as a risk-avoidance strategy in plants to conserve water when soil conditions predict future water deficit [13]. In irrigated crops this risk-avoidance mechanism may be detrimental to yield because farmers will usually irrigate before the risk is realized. Many important advances in understanding root-shoot signalling have been made at the biochemical and physiological level [14], but little or no information is available about the genetic control of this process. We aim is exploit recent developments in genetics and genomics to identify genetic loci that influence root-shoot signalling strength in a Solanaceous model crop. This information will be suitable for use in breeding potato varieties whose yield is less sensitive to mild fluctuations in soil water content. Deliverables· A description of genetic diversity of root traits in both potato and tomato· QTL for root traits that influence water and nutrient use· Molecular markers for selection of Solanaceous crop cultivars with altered water use

01: Development of assays for root traits suitable for replicated QTL trialsAssays for root growth, root penetration and root-shoot signalling will be optimized for use in objectives 02 to 04.
02: Identification of QTL for root traitsRoot trait assays will be performed on mapping populations. 03: Resolution of QTLRobust QTL for root traits will be further investigated to reduce the size of the QTL mapping interval. This will improve the association between molecular markers and root traits and lead towards candidate gene identification.
04: Assessment of genetic diversity in root depth and penetrationGenetic variation in rooting depth and root penetration will be measured within cultivars and wild species of Lycopersicon and Solanum.
05: Technology transferInformation on assay methods, genetic diversity, QTL and molecular markers will be reported in scientific journals and communicated to plant breeders.
Time-Scale and Cost
From: 2005

To: 2010

Cost: £638,300
Contractor / Funded Organisations
Warwick - HRI
Allocated - WHRI              
Natural Resource Use              
Natural Resources and Labour              
Protected Cropping              
Sustainable Farming and Food              
Fields of Study