Some species of FHB posses the capability to decimate crops in the few weeks leading up to their harvest (WCISłOA, 2016).
Fusarium produces mycotoxins that have adverse health effects on humans and animals
1.1 Research justification
The control and prevention of foodborne diseases are public health targets internationally, for this reason extensive testing has been created for quantification of foodborne fungi, bacteria and viruses (RODRIGUEZ-LÁZARO, 2013).
1.2 Research question
1.3 Hypothesis
1.4 Objectives
2 Literature review
2.1 Fusarium disease complex
F. graminearum s.s. is part of the monophyletic fungal complex otherwise referred to as (FGSC) F. graminearum species complex, consisting of 16 phylogenetic species (SARVER et al, 2011). Fusarium head blight (FHB) is a fungal disease affecting small grain cereals mainly wheat, barley, oats, rye and maize (Buerstmayr et al, 2002). The fungus will infect the head of the wheat plant during anthesis, turning it salmon to white in colour forming lieu of the healthy grain (Anna et al. 2015; Sutton, 1982). Fusarium Graminearum is viewed as one of the most destructive diseases to occur in wheat (Humphries, 2009). Many countries including the U.K. have imposed a maximum limit of deoxynivalenol (DON) in grain (Ouelletb et al, 2016; Berrie, 2005) for human consumption and guideline limits for livestock feed grain (AHDB, 2015) Levels of DON are tested for at mills (HGCA, 2013). The main concern of U.K. wheat production are strains F. culmorum and F. graminearum (Wise, 2015).
2.2 Fusarium life cycle
Fusarium head blight disease in wheat is commenced by airborne spores reaching flowering spikelets, then germinating and infiltrating the plants using natural gaps such as the palea and base of the lemma or passing degenerating anther tissues (BUSHNELL et al, 2003). The fungus will then grow asymptomatically and intercelluarly (GUENTHER, 2005; JANSEN et al, 2005) spreading through pith and xylem (BUSHNELL, 2003). This stage is often referred to as biotrophic, however it lacks intracellular growth and does not keep with the traditional definition (JANSEN, 2005). The fungus radially spreads and necrosis starts whilst the fungus grows and quickly colonises the tissue. At this stage the symptoms are water soaking, mainly of the chlorenchyma, after this bleching of the colonised tissue occur. The premature bleching of the head tissue is a sign that the head is infected in a field environment, the normal symptom of head blight in wheat is the bleached tissue forming seven florets in the middle of the wheat head.
Plate 1.
Once the wheat florets are infected, the fungus shows the genes for DON biosynthesis almost instantly (JANSEN et al, 2005). DON in wheat is a virulence factor, it causes tissue necrosis
Crop residues managed correctly can improve the soils organic matter nutrient cycling and matter dynamics, therefore providing a well-suited environment for plant growth (Y. SINGH et al, 2005). However, the crop residues host plant pathogens that are able to live on them as saprophyates that generate a source of inoculum that develop plant disease epedemics (VAN TOOR et al, 2013; JøRGENSEN, 2007; SUTTON, 1982; HUBER et al, 1965). The main inoculum for fusarium develoment are ascospores created by G.zeae left on the crop residue remaining on the surface of the soil post harvest and provide an environment for overwintering of the fungus (PEREYRA, 2008; SUTTON, 1982).
2.3 Plant breeding
2.4 Inoculation
2.5 Resistance
Genetic resistance to FHB by Fusarium Graminearum is needed to reduce the loss of quality and grain yields the disease causes (Anderson et al; 2001). FHB resistance is a complex and quantitative trait with parts of wheat genome contributing towards it. Three decades of vast breeding efforts have resulted in few wheat cultivars being produced showing high resistance to FHB. Few genetic sources demonstrating resistance to FHB have been discovered, with the molecular mechanisms of resistance staying unknown (BARI and Jones, 2009). The F. graminearum and plant genes causing the spread of infection as well as the defence mechanisms have been scrutinised heavily, however the majority of cereal genomes are yet to be sequenced and most biological mechanisms depend on the expression level of a sequence of genes, the approach is based on an extensive gene combination search which is highly difficult and extremely inefficient (BOSWELL and Davidson, 2012; G. BOSWELL et al. 2007; DAVIDSON, 2007; TU, 1950).
3 Materials and Methods
3.1 Subtitle of Materials and methods 1
The 37 wheat cultivars used for the first experiment and 32 used for the second were sourced from the HGCA recommended list 2012/13.
Each of the cultivars were placed in 3 inch plastic pots then the 8 replicates were covered with John Innes No2 compost. Sterilised loam, sand and peat is contained in the compost at 2:1:1. To prevent confusion between dates and varieties each pot was labelled.
The pots were set in an unheated glasshouse to create a continuous environment that was the same for each cultivar. The glasshouse will raise the intensity of light and temperature compared to a field environment. Therefore reducing the time reducing the time taken to anthesis and accelerating the spread of the F.graminearium infection (Adams and Langton 2009).
3.2 Subtitle of Materials and methods 2
Each seed was vernalised for a 6 week period in a petri dish placed on damp filter paper then planted 2 seeds in each plant pot in an unheated glass house during November. Cultivars were thinned to a single seed and thinned again to a single main tiller at the beginning of stem extension. They were replicated 8 times in a randomised block design.
The fungal spore inoculum of F.graminearum was created on PDA agar and a mung bean extract.
1L of dH2O was boiled prior to 40g of mung beans being added to create the media mixture, it was then boiled for another 20 minutes. The beans were filtered out, then 39g of PDA agar was added and mixed and then transferred to an auto-cave for 20 minutes. It was then cooled in a water bath, once set the plates were poured and APDA was added along with F.graminearum to the PDA plate and mung bean allowing it to grow for a week. Transferring the plug to a clean mung bean PDA plate. The spores take between 7 to 10 days to produce prior to 5ml of sterile water being added to flood the plate. Glass ‘hockey stick’ is used to dislodge to spores then pouring the solution into a beaker to ensure spore the spore concentration using a hemacytomter.
The cultivars were inoculated by injecting 10µl of spore suspension mid anthesis at the rate 1 x 106 spores per ml at two adjacent spikelets at the middle point of the wheat spike then marked using typex to enable identification for assessing disease.
Table 1. Gender, age and estimated weight of tamarins.
Subject No: Name D.O.B. Age when training commenced Estimated weight (g)
Source: XXXX
3.3 Subtitle of Materials and methods 3
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Figure 2. Floor plan of tamarin enclosure (measurements in metres).
Plate 2. Tamarin enclosure.
a) Front view of outdoor enclosure. b) Side view of outdoor enclosure showing full height.
Table 2. Gender, age and estimated weight of tamarins.
Column title Column title Column title
Source: XXXX
4 Results
4.1 Subtitle of Results 1
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4.2 Subtitle of Results 2
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