H. L. Barnett

A Destructive Mycoparasite, Gliocladium Roseum

SUMMARYGliocladium roseum was shown to be a destructive parasite on numerous other fungi. In fact, no fungus tested was immune to attack at all stages of development. In the present preliminary stu...

Mode of Parasitism and Host Range of Piptocephalis Virginiana

The genus Piptocephalis belongs to the order Mucorales. The char? acteristic slender, dichotomously branched sporophores, which terminate in deciduous head cells bearing clusters of spore-chains, make this genus easily distinguishable from all others of this order. All known species are obligate parasites of other fungi. The contributions of most of the early workers to our knowledge of Piptocephalis were mainly taxonomic (de Bary, 1865; van Tieghem, 1875; Bainier, 1883; Vuillemin, 1887). Brefeld (1872) studied the morphology, mode of parasitism and zygospore formation of P. freseniana. Matruchot (1900, 1903), using a species which he described and named P. tieghemiana, was the first to make an extensive study of the host range. He tested representatives of all classes of fungi, and found parasitism to occur on ten members of the Mucoraceae, and one of the Pilobolaceae. No species tested outside the order Mucorales was parasitized. Until recently, no species of Piptocephalis had been found to parasitize any fungus outside the Mucorales. Dobbs and English (1954) described and named a new species, P. xenophila, which not only parasitizes certain species of Ascomycetes and Fungi Imperfecti, but grows and sporulates better on these hosts than on some species of Mucorales. The work of Ayres (1933, 1935), on the parasitism of Dispira cornuta, is of interest because of the similarity of this fungus in mor? phology, mode of parasitism and host range to most species of Pipto? cephalis. However, D. cornuta is able to grow on certain high nitrogen media in the absence of a host.

Parasitism and Nutrition of Gonatobotrys Simplex

Most of the early studies of fungi parasitic on other fungi have dealt principally with mode of parasitism or host range. Ayers (1933, 1935, 1941) was one of the first investigators to emphasize nutritional and physiological aspects of mycoparasitism. Several investigations have dealt recently with physiology of biotrophic mycoparasites and the influence of environment and nutrition on their parasitic activities. Barnett and Lilly (1958) reported that Calcarisporium parsiticumn Barnett parasitizes species of Physalospora and related fungi by making close contact with the host and absorbing nutrients through small, specialized buffer cells at the point of contact. This fungus was later cultured axenically on media to which extracts of other fungi were added. Berry and Barnett (1957) and Berry (1959) described the parasitism of Piptocephalis virginiana Leadbeater & Mercer, which obtains nutrients from other species of Mucorales by means of haustoria. This mycoparasite, in contrast to C. parasiticurm, has never been grown in the absence of a living host. A short time later, Shigo (1960) showed that Gonatobotryum fuscum Sacc. parasitized species of Ceratocystis and related genera by means of foot-like, absorptive hyphae which made contact and adsorbed nutrients without penetrating the host cells. He also described a condition which

NUTRITIONAL REQUIREMENTS FOR AXENIC GROWTH OF SOME HAUSTORIAL MYCOPARASITES

SUMMARY A study of the nutritional conditions required for axenic growth of five biotrophic haustorial mycoparasites, with emphasis on Tieghemiomyces parasiticus, was made on a basal casein hydrolysate medium. Four species failed to utilize glucose or other sugars and sugar utilization by the fifth one is doubtful. Glycerol was utilized readily by all species. Casein hydrolysate was not utilized as a carbon source. Four species were totally deficient for thiamine. T. parasiticus was favored by unusually high concentrations of thiamine and also was highly deficient for biotin. T. parasiticus and Dimargaris verticillata grew more rapidly on media with high concentrations of casein hydrolysate in the presence of glycerol but no growth of either parasite occurred on media with single amino acids. It appears that specific requirements for carbon sources, nitrogen sources, and vitamins may be common among the biotrophic mycoparasites. The nutritional requirements of the biotrophic (obligate) mycoparasites have remained a challenging problem. Extensive axenic growth of three biotrophic contact mycoparasites has been obtained following the addition of a growth factor, mycotrophein, obtained from a water extract from certain other fungi, to an appropriate basal medium containing glucose as the carbon source. These parasites are Calcarisporium parasiticum Barnett (Barnett and Lilly, 1958), Gonatobotrys simplex Corda (Whaley and Barnett, 1963), and Gonatorrhodiella highlei Smith (Gain and Barnett, 1970). However, few of the haustorial mycoparasites, which belong to the Mucorales and for the most part parasitize other Mucorales, are known to make more than a trace of axenic growth on the usual laboratory media. It is generally assumed that these media are incomplete for these parasites. Benjamin (1959, 1961) has made a morphological and taxonomic study of a number of the haustorial mycoparasites and has reported that 1 Published with the approval of the Director of the West Virginia University

Growth and Sporulation of Species and Isolates of Cylindrocladium in Culture

SUMMARYSeveral species of Cylindrocladium, comprising 58 isolates, were studied in culture to determine their trophic and sporulation responses to various nutrients and to light. Cylindrocladium av...

The Effects of Humidity, Temperature and Carbon Dioxide on Sporulation of Choanephora Cucurbitarum

Under the usual laboratory conditions in test tubes, flasks or tightly closed Petri dishes, the high humidity and poor ventilation create abnormal conditions which may permit growth of the mycelium, but often greatly reduce sporulation of many fungi. This may be due to unfavorable humidity, insufficient oxygen or to an accumulation of carbon dioxide or other gases resulting from the metabolism of the fungus. Comparatively few studies of the effects of the conditions of the atmosphere in the culture vessels have been made, but it is known that these factors are important for some fungi. Henry and Andersen (1948) have shown that an accumulation of ammonia reduces sporula? tion of Piricularia oryzae, and Bright et al (1949) reported that an increase in carbon dioxide reduced sporulation of Saccharomyces cerevisiae.

The relation of thiamin to the production of perithecia by Ceratostomella fimbriata.

It is a well established fact that many fungi are unable to synthesize certain necessary vitamins, or are capable of only limited synthesis. If normal vegetative growth is to result, these vitamins must be supplied by the medium in or on which these fungi grow. In contrast with our knowledge of the dependence upon vitamins for normal vegetative growth, little is known regarding the relation of these vitamins to sexual reproduction in fungi. Robbins and Ma (6) postulated that the formation of sex organs by various vitamin-deficient fungi would be found to be associated with the specific vitamin for which a fungus is deficient. Barnett and Lilly (1) have recently shown that, for Sordaria fimnicola, a sufficient amount of biotin in the medium is necessary for (a) normal vegetative growth, (b) the production of perithecia and (c) the formation of normal mature ascospores, and that the amount of biotin required increases in the above order. The number of mature ascospores formed by this fungus was directly proportional to the amount (sub-optimal) of biotin added to the medium. Hawker (3), working primarily with Melanospora destruens, reported that an exogenous source of biotin was necessary for abundant mycelial growth and that fruiting occurred only on the further addition of thiamin.

PARASITISM AND AXENIC GROWTH OF THE MYCOPARASITE GONATORHODIELLA HIGHLEI

Gonatorhodiella highlei A. L. Smith is found in nature as a biotrophic parasite of Nectria coccinea (Pers.) Fries on bark of American beech (Fagus grandifolia Ehrh.). The host range was extended to include Verticillium albo-atrum Reinke & Barthold, Cladosporium sp., Tritirachium sp., Graphium sp., and Chaetomella raphigera Swift. The source and concentration of nitrogen in the medium affected the growth of the parasite on N. coccinea. Certain organic nitrogen sources at high concentrations (above 0.42 g nitrogen/liter) were inhibitory, due to liberation of ammonia by the host. The concentration of thiamine in the medium also affected growth of the parasite on N. coccinea. Parasitism occurred only when the concentration of thiamine was higher than the optimum for host growth. White light (200 ft-c) inhibited growth of G. highlei on Nectria coccinea and Tritirachium sp. and inhibited axenic growth of the parasite. The effect was directly on the parasite and was not due to light-induced changes in the medium. A nutrient required G. highlei for spore germination was found in beech bark. The compound is water soluble, organic, and has a low molecular weight. Both this compound and mycotrophein, an unidentified growth factor, are required for axenic growth.

Axenic Growth and Nutrition of Gonatobotryum Fuscum

SUMMARY Gonatobotryum fuscum, a contact biotrophic mycoparasite, has been cultured axenically for the first time, the best medium being a glucoseyeast extract medium (10-2 g/liter) supplemented with thiamine (4-8 mg/ liter), biotin (0.2-0.4 mg/liter), and mycotrophein, a water soluble compound extracted from the host and some nonhost fungi. This parasite is the fourth species of its type to be studied and is similar to the other three (Calcarisporium parasiticum, Gonatobotrys simplex, and Gonatorhodiella highlei) in that they are deficient for the same growth factor, mycotrophein. The optimum concentrations of thiamine and biotin were unusually high and may reflect the difficulty with which these vitamins enter the cells. The addition of dimethyl sulfoxide (DMSO) increased growth rate, total growth and glucose utilization. Of the 13 carbon sources tested, G. fuscum made much greater growLh

Mycoparasitism of Dispira Simplex and D. Parvispora

Physiological studies of the haustorium-producing, biotrophic mycoparasites have been limited primarily to two genera, Dispira and Piptocephalis. Ayers (1933, 1935) was a pioneer in the physiological study of this group of parasites and reported that the host range of Dispira cornuta Van Tiegh. was limited to several other species of Mucorales and that the host nutrition affected the degree of parasitism. Berry (1959), Berry and Barnett (1957), and Shigo et al. (1961) have made physiological studies of Piptocephalis virginiana Leadbeater & Mercer and P. xenophila Dobbs & English, which have a similar mode of parasitism. Two additional species of Dispira recently became available for study and physiological comparison. Benjamin (1959) described D. simplex Benjamin, but was unable to culture it with species of Mucorales. Later, he reported this fungus as a parasite on a species of Chaetomium (Benjamin, 1961). However, Indoh (1965) has reported this species from Japan growing on Mucor sp. and Circinella sp. Another species, D. parvispora Benjamin, was described and reported as a parasite on Cokeromyces recurvatus Poitras (Benjamin, 1963). The present paper deals with the mode of parasitism, host range, and axenic growth of D. simplex and D. parvispora. It is a portion of a broad study of mycoparasitism at West Virginia University.