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Strategic approaches and technology transfer to control and manipulate mushroom initiation for crop uniformity and effecient resource use - HH3613SMU

The production of mushrooms involves a phase change (initiation) from vegetative to reproductive growth. This phase change is achieved practically by environmental manipulation and the presence of naturally occurring bacteria. This is an uncertain practice leading to variation in mushroom size and quality uniformity thereby preventing the application of automation to the labour intensive harvesting process. Achieving the correct number of initials on the casing layer is critical in obtaining the maximum yield of quality mushrooms. Sparse initiation results in depressed yields, whereas too many initials result in dense populations of poor quality mushrooms which are difficult to pick.The research of this contract is aimed at controlling initiation with much greater precision. The research project is composed of a technology transfer component for early use by the mushroom industry and a strategic component aimed at identifying the molecular mechanism of initiation and model the interactions between the initiation stimuli and the genes controlling initiation to develop a step change in initiation procedures. The technology transfer in this project is aimed at improving mushroom size and quality uniformity by using knowledge established from a current DEFRA funded project on initiation (HH1334SMU). This established: 1. Different Pseudomonas putida isolates can stimulate initiation of Agaricus bisporus primordia and fruitbodies to different levels. 2. 8-carbon compounds produced by the mushroom mycelium can inhibit initiation. 3. Adsorbent materials in the casing can stimulate initiation by removing inhibitory compounds. These findings were made on sterile casing in the laboratory. The challenge is to transfer and scale-up this work to the mushroom crop. Different Pseudomonas putida isolates, inhibitor compounds and adsorbent materials will be added to non-sterile casings and the extent of microbial manipulation will be examined together with the effect on initiation, mushroom size and quality uniformity. These treatments will be presented to the industry in on-farm experiments and demonstration trials. In the strategic part of the research, the genes involved in initiation will be identifed by high throughput genomic technologies. The genes identified to have changing transcript levels during initiation will be characterised in terms of sequence, time and abundance of expression. Hypotheses on the mechanism of initiation and the role of these genes will be devised. These hypotheses will be tested by gene silencing and over-expression for specific genes and examining the effect on the initiation process. Mushroom strains with altered gene expression will be grown in microcosms, aerated flasks and small scale crop experiments to determine the effects of gene manipulations on initiation and cropping behaviour (mushroom size and quality uniformity). The responses of P. putida, adsorbents, volatiles and agronomic/environmental variables on initiation will be analysed and their effects on gene expression determined. This will deliver detailed knowledge of the mechanism of initiation and molecular probes to act as early/key indicators of initiation effficiency which can feed directly into industry practice or be used in agronomic trialing and breeding programmes.
1) Technology transfer of the effects of P.putida isolates, 8-carbon compounds and adsorbent materials on initiation, mushroom size and quality uniformity under commercial cropping conditions.2) Determine differentially expressed genes between vegetative mycelium, undifferentiated aggregates, differentiated primordia and mushroom pins (early stage sporophores) by Suppression Subtractive Hybridisation (SSH).3) Determine gene expression profiles during initiation under standard cropping conditions and comparative gene expression in response to different initiation stimuli by micro-arrays analysis.4) Identification, sequencing and quantitative expression analysis of key initiation genes.5) Generate strains with modified gene expression to test function/role in initiation. 6) Determine the effects of gene modification on initiation behaviour, sporophore development, gene expression and responses to agronomic variables by culturing strains in microcosm, aerated flask and non-sterile tray systems.7) Explore opportunities for commercial adaptation/up take of the strategic outputs generated.
Time-Scale and Cost
From: 2004

To: 2009

Cost: £995,934
Contractor / Funded Organisations
Warwick - HRI
Allocated - WHRI              
Natural Resources and Labour              
Protected Cropping              
Sustainable Farming and Food