Studies on Claviceps purpurea (Fr.) Tul. parasitic on Phragmites communis Trin

Abstract

S U M M A R YIsolates from C. purpurea sclerotia occurring naturally on Phragmites communis usually sporulated vigorously on the culture medium employed, and their failure to produce alkaloid in vitro was associated with a thin white growth form. Such isolates also failed to produce sclerotia on the host plants tested. A variant having a plectenchymatic morphology in vitro and producing a thick pigmented non-sporulating growth form yielded alkaloid (up to approximately 300 ,ug/ml mainly AS-9 and A9-10 lysergic acids and chanoclavine) in surface or submerged culture and developed typical ergot sclerotia (containing 0.2-0-4 yo alkaloid, mainly ergotoxine and ergotamine) in uivo.Improved alkaloid yield in vitro was obtained from a strain reselected after passing through a parasitic phase.Aetiological aspects of the P. communis ergot are discussed. I N T R O D U C T I O NDuring a programme of research, carried out over several years, a large number of isolates from C.purpurea sclerotia collected from various host plants have been screened for the production of ergot alkaloid in vitro. This paper presents details of one of the very few alkaloid-producing strains which were found and describes comparative studies with related strains involving growth and alkaloid production in vitro and in vivo. M A T E R I A L S A N D M E T H O D SAlkaloid assay, culture media and conditions, host plant inoculation, and sclerotial germination were as previously described (Mantle, 1969). I n submerged culture the first (seed) stage flasks were incubated for 7 days at 24 "C, homogenized in an Atomix blender for 20 sec, and a 10 yo inoculum transferred to second-stage flasks.Where a third stage was used, this was inoculated with a 10 % transfer from 3-day-old second-stage flasks.Ascospore septa and nuclei were demonstrated by cotton blue and Giemsa staining, respectively. 426 P. G. MANTLEHost plant material was obtained as follows :Svalofs winter rye (short-strawed

Comparative Ergot Alkaloid Elaboration by Selected Plectenchymatic Mycelia of Claviceps purpurea through Sequential Cycles of Axenic Culture and Plant Parasitism

“…Somewhat similarly, the Phragmites isolates had also only weakly parasitised rye, abnormality being a lateral attachment to an aborted seed where the sclerotial tissue replaced the embryo side of the seed. This suggested that the parasite had only partly invaded the unfertilised ovary and had developed sclerotial tissue while the uninfected ovary sector differentiated into an incomplete seed [9]. More extreme aberration was recorded where a viable seed developed distal to a sclerotium in a rye floret [23], further illustrating unconventional occurrences in C. purpurea parasitism.…”

“…Tul., but a new name (C. arundinis) has been proposed [24]. Notably, the C. microcephala descriptor had previously been considered [9]. Finally, C. purpurea sensu stricto might be applied to the present study for the isolate from A. myosuroides, since this grass is a cereal crop weed.…”

“…Isolation of the fungus from sclerotial tissues was as previously described [8,9]. Ergots were cut into two or three pieces to expose the medullary tissue, from which new mycelium could arise.…”

“…Biology 2020, 9,41 9 of 14 from a sclerotium on A. myosuroides commenced with demonstration of typical parasitism on Fourex rye (Figure 3) during which ergotoxines were again the principal alkaloid. To find amongst the predominantly white forms a purple plectenchymatic form in axenic culture could not have been expected.…”

“…Highly selected isolates from English Gramineae, e.g., Spartina townsendii H. et J Groves and Phragmites communis Trin. [8,9], had an ecology which at least made them of low or no epidemiological risk towards cereal crops. They proved unexpectedly fruitful in expressing in axenic culture a pigmented growth form described as plectenchymatic.…”