Characterisation of Botrytis species associated with neck rot of onion in Australia
Neck rot of onion has commonly been attributed to two fungal pathogens, Botrytis aclada (syn. B. allii) and B. byssoidea. However, in other countries, a recently developed PCR technique using sequence characterised amplified region (SCAR) primers (BA2f/BA1r) followed by ApoI digestion of the amplification product, has shown the presence of two groups within B. aclada, B. aclada AI and B. aclada AII syn. B. allii. This method was used to characterise Botrytis spp. of the B. aclada/B. allii complex associated with onion seed and bulbs in Australia. A total of 24 Botrytis isolates, including two from seed and ten from bulbs (Tasmania), five from seed (South Australia), and one from seed and six from a culture collection originally isolated from five bulbs and one stipe (New South Wales), were characterised. Of the 24 isolates, one was identified as B. cinerea, one as B. aclada AI, and 22 as B. aclada All syn. B. allii.
Analysis of three biological control agents and naturally-occurring fungal colonizers on the survival of sclerotia of Botrytis squamosa, Sclerotinia sclerotiorum and Sclerotium cepivorum
ANALYSIS OF THREE BIOLOGICAL CONTROL AGENTS AND NATURALLY-OCCURRING FUNGAL COLONIZERS ON THE SURVIVAL OF SCLEROTIA OF BOTRYTIS SQUAMOSA, SCLEROTINIA SCLEROTIORUM AND SCLEROTIUM CEPIVORUM Laura C. Barbison Advisors: University of Guelph, 2014 Professor G. J. Boland Professor M. R. McDonald Management of sclerotia-forming phytopathogenic fungi is difficult due to the resilience of their sclerotia within soil. This thesis assessed the efficacy of three biological control agents (BCAs), Coniothyrium minitans, Microsphaeropsis ochracea, and Trichoderma atroviride, on laboratory-produced (LP) sclerotia of Botrytis squamosa, Sclerotinia sclerotiorum and Sclerotium cepivorum under field conditions for 20 months. Trichoderma atroviride was most consistent, reducing survival of B. squamosa and S. sclerotiorum to 19 and 23%. S. cepivorum did not vary. Further investigations compared the survivability of LP and field-produced (FP) sclerotia of S. sclerotiorum. Survival of LP sclerotia of S. sclerotiorum was greater than that of FP, which were heavily colonized with other fungi. Colonizers were isolated, identified, and evaluated for antagonistic and pathogenic abilities. 80% of isolates demonstrated antagonistism, and two isolates demonstrated pathogenicity. It is evident that sclerotia are not sterile propagules, and that antagonistic soil-dwelling microorganisms are important influential factors on sclerotial
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.