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Species of the genus Colletotrichum Corda are responsible for many diseases of economically important crops world-wide. One particularly susceptible crop is strawberry (Fragaria spp.) on which Colletotrichum spp. cause extremely destructive anthracnose diseases, characterised by black necrotic lesions on any part of the plant. Three "species" have been implicated in the disease: C. acutatum, C. jragariae, and C. gloeosporioides. C. acutatum is considered the causal organism of strawberry blackspot in Europe and is subject to quarantine regulations within the EU; c.jragariae has only been found in the Americas and was formerly considered the sole cause of strawberry anthracnose in North America; and C. gloeosporioides is a heterogeneous "species aggregate" which has a morphological range which can encompass examples of other "species", especially C. jragariae. The absence of a reliable test for distinguishing these "species" - classical morphological approaches are unsatisfactory - led to an international multi-disciplinary project to characterise Colletotrichum pathogens of strawberry and develop diagnostic tests for individual taxa (\,,,;,,,\..c_,,\_ \:x~ t:k._ ~0). The research reported in this thesis has demonstrated the utility of a multidisciplinary approach to the systematics of Colletotrichum pathogens of strawberry. Data obtained have supported taxon groupings at different levels. The use of mtDNA provided data of two complementary types. Firstly, the NMS primers were utilised in amplification of a fragment of "species aggregate" -specific size (with three notable exceptions) from the mitochondrial small subunit rDNA. Secondly, the Hae III restriction digests of A+T-rich DNA were able to highlight groupings below the level of species aggregates. This latter method was able to distinguish the meioticallyreproducing strains of C. jragariae from anamorphic isolates and elicited two distinct subgroups in C. acutatum. PCR techniques previously described by Mills and co works and Freeman and Rodriguez were assessed for their utility and reliability. Isozyme analyses were moderately useful for taxon differentiation at an infraspecific level with the esterase systems.Study of extracellular enzyme activities using 4 MU substituted compounds was of limited diagnostic use. Additional physiological and biochemical tests did not reveal many discriminatory tests. A few tests, however, did reflect the greater vigour generally displayed by C. jragariae isolates. Utilisation of glucuronamide and growth rate on casein were two such tests. The physiological and biochemical tests were demonstrably more useful when put together with the data from EU Project colleagues and subjected to cluster analyses and ordination techniques, then when analysed as discrete tests. Colleagues in collaborating laboratories undertook a battery of tests including molecular, physiological and biochemical studies. It is appropriate to use the entire set of information obtained from the overall EU-Project in order to fully define the groups. The results reported in this thesis can stand alone, however, allowing discrimination of the taxa at several levels.

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Two factorial greenhouse experiments were performed to determine the effects of four arbuscular mycorrhizal fungi (AMF) species (Glomus arenarium, Funneliformis caledonius, F. mosseae, and Rhizophagus irregularis) and a root endophyte (Piriformospora indica) on four ‘day-neutral’ strawberry (Fragaria × ananassa Duch.) cultivars (‘Albion’, ‘Charlotte’, ‘Mara des Bois’, and ‘Seascape’), and mixed-AMF species (R. irregularis + F. mosseae) on cv. ‘Seascape’, under salt conditions (0-200 mM NaCl). In its biomass, ‘Seascape’ was more tolerant to salinity than the other cultivars. Cultivars responded differently to fungal inoculation as to salinity. G. arenarium had a negative effect on plant growth and ‘Mara des Bois’ responded negatively to inoculation. Among the remaining inoculants and cultivars, fungal-symbiosis was beneficial to growth. R. irregularis alleviated the symptoms of salt stress and improved fruit quality to a higher degree than the other AMF species and the root endophyte. Our results support the use of bio-inoculants in salty horticultural areas.

Two factorial greenhouse experiments were performed to determine the effects of four arbuscular mycorrhizal fungi (AMF) species (Glomus arenarium, Funneliformis caledonius, F. mosseae, and Rhizophagus irregularis) and a root endophyte (Piriformospora indica) on four ‘day-neutral’ strawberry (Fragaria × ananassa Duch.) cultivars (‘Albion’, ‘Charlotte’, ‘Mara des Bois’, and ‘Seascape’), and mixed-AMF species (R. irregularis + F. mosseae) on cv. ‘Seascape’, under salt conditions (0-200 mM NaCl). In its biomass, ‘Seascape’ was more tolerant to salinity than the other cultivars. Cultivars responded differently to fungal inoculation as to salinity. G. arenarium had a negative effect on plant growth and ‘Mara des Bois’ responded negatively to inoculation. Among the remaining inoculants and cultivars, fungal-symbiosis was beneficial to growth. R. irregularis alleviated the symptoms of salt stress and improved fruit quality to a higher degree than the other AMF species and the root endophyte. Our results support the use of bio-inoculants in salty horticultural areas.

The gut microbiota has been implicated in both health and disease. As such, diet is a significant determinant of gut health, whereby diet induced dysbiosis is associated with cardiometabolic risk. Interestingly, a higher proportion of Firmicutes and a lower proportion of Bacteroidetes are implicated in obesity. Strawberry polyphenols have been shown to reduce cardiovascular disease risk in addition to exhibiting prebiotic activity by increasing probiotic bacteria in the gut. Polyphenols have also been shown to reduce the ratio of Firmicutes to Bacteroidetes. Therefore, dietary modifications such as strawberry consumption may help improve health outcomes through the gut. The objective of this study was to analyze whether 13 g freeze dried strawberry powder (~1 cup/d fresh) consumption reduces the Firmicutes:Bacteroidetes ratio and increases microbial diversity and beneficial bacteria like Lactobacillus and Bifidobacterium. This study was a 5-week free-living diet intervention trial conducted at California Polytechnic State University, San Luis Obispo with expansion to the Eye Medical Center of Fresno. Participants (n=10) had a mean age of 60.5 ± 9.13 years and had a mean body weight of 74.71 ± 10.61 kg. The participants completed a 3-week washout before a 2-week diet intervention. Participants maintained their normal diet throughout the study while eliminating foods high in polyphenols and probiotics. Upon completion of the study, no significant differences were found for body weight (p=0.22) or BMI (p=0.26). Likewise, no significant differences were found for macronutrient, vitamin, or mineral intake except for sugar (p=0.03), vitamin B12 (p=0.03), and fruit (p=0.0014). Bacteria abundance and diversity were not found to be statistically significant following intervention. Since strawberry supplementation was not associated with a significant change in the relative abundance of bacteria with the dose and duration administered, a randomized controlled trial would better determine the effect of strawberry consumption on gut health.