Physalospora

Abstract: Apple ringrot inflictssevereeconomiclosses inthe main apple producing areas of East Asia. The causal agent of the disease has been variously identified as Macrophoma kuwatsukai, Physalospora piricola and Botryosphaeria berengeriana f. sp. piricola ,a lthoughB. dothidea is currently the most widely accepted pathogen name. The taxonomic uncertainty has delayed research that is needed to manage effectively this destructive disease. In the present study, gene- alogical concordance phylogenetic species recognition (GCPSR) was applied to pathogenic fungal isolates from apple and pear from several locations in China, along with several reference isolates. Phylogenetic results based on se- quences of four nuclear loci (ITS, EF-1α, HIS and HSP) revealed the existence of two species within the examined isolates. One includes an ex-epitype isolate ofB. dothideaand the other includes an isolate that was previously designated as B. berengeriana f. sp. piricola. Morphologically, the latter taxon presented an appressed mycelial mat on PDA whereas B. dothidea displayed columns of aerial mycelia reaching the lids, and conidia of the latter species were longer than B. dothidea. Botryosphaeria dothidea had a faster growth rate than the latter taxon under relatively high temperatures. Path- ogenicity tests showed that on pear stems the latter taxon caused large-scale cankers along with blisters whereas B. dothidea was non-pathogenic, but on apple shoots the two fungi induced large and small wart-like prominences, respectively. Overall, this cryptic species demonstrated suffi- cient genetic variations and biological differences from B. dothidea. As a result of taxonomic study, we described here the latter taxon in a new combination, Botryosphaeria kuwatsukai and designate an epitype. Both B. kuwatsukai and B. dothidea are considered to be the main causal agents for apple ring rot in China and Japan.

Abstract: 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