THE PROCESSES OF ANTHER DEHISCENCE AND POLLEN DISPERSAL III. THE DEHYDRATION OF THE FILAMENT TIP AND THE ANTHER IN THREE MONOCOTYLEDONOUS SPECIES

The relationship between anther dehiscence and dehydration of the filament tip and the connective tissue were followed in Gasteria verrucosa (Mill.) H. Duval, Allium cepa L. and Lilium hybrida cv.'Enchantment'using various microscopical techniques, including direct observations of living tissues in the SEM.
In G. verrucosa anther dehiscence immediately follows anthesis, with concomitant dehydration and shrivelling of the filament tip. In L. hybrida the filament tip dehydrates and shrivels before anthesis. The anthers start to dehisce immediately after anthesis. In A. cepa the filament tip dehydrates and shrivels slowly after anthesis and dehiscence, which may take up to several days, correlates with the rate of extension of the filament.
The attenuated period of dehiscence in A. cepa may be related to the absence of stomata on the anther. Experiments on xylem conductivity and transpiration reveal that the presence of continuously open stomata on the anthers sets the time of dehiscence after anthesis in G. verrucosa and L. hybrida.
The shrinking filament tip in all three species functions as a hinge which suspends the dangling anther after dehiscence. The uniformly thickened epidermal cell walls on the anthers opposite the filament prevent the outwardly bending locule walls from embracing the filament.     

Sexual selection in fungi

The significance of sexual selection, the component of natural selection associated with variation in mating success, is well established for the evolution of animals and plants, but not for the evolution of fungi. Even though fungi do not have separate sexes, most filamentous fungi mate in a hermaphroditic fashion, with distinct sex roles, that is, investment in large gametes (female role) and fertilization by other small gametes (male role). Fungi compete to fertilize, analogous to ‘male‐male’ competition, whereas they can be selective when being fertilized, analogous to female choice. Mating types, which determine genetic compatibility among fungal gametes, are important for sexual selection in two respects. First, genes at the mating‐type loci regulate different aspects of mating and thus can be subject to sexual selection. Second, for sexual selection, not only the two sexes (or sex roles) but also the mating types can form the classes, the members of which compete for access to members of the other class. This is significant if mating‐type gene products are costly, thus signalling genetic quality according to Zahavi's handicap principle. We propose that sexual selection explains various fungal characteristics such as the observed high redundancy of pheromones at the B mating‐type locus of Agaricomycotina, the occurrence of multiple types of spores in Ascomycotina or the strong pheromone signalling in yeasts. Furthermore, we argue that fungi are good model systems to experimentally study fundamental aspects of sexual selection, due to their fast generation times and high diversity of life cycles and mating systems.     

中国粪生子囊真菌Ⅰ:中国新记录属异接柄孢属和新记录种盘孢锥毛壳(英文)

报道了中国粪生真菌的1个新记录属——异接柄孢属和1个新记录种——盘孢锥毛壳。在观察所采集标本的基础上,概述了异接柄孢属的特征,并描述了美丽异接柄孢和盘孢锥毛壳的形态特征。文中还讨论了所采集的标本与模式标本原始描述的差别。     

Tour of Truffles: Aromas,Aphrodisiacs, Adaptogens,and More

Truffles are the fruiting bodies of ascomycete fungi that form underground. Truffles are globally valued, culturally celebrated as aphrodisiacs, and highly sought-after delicacies in the culinary world. For centuries, naturalists have speculated about their mode of formation, and in cultures surrounding the Mediterranean Sea, many species have been prized as a delectable food source. Truffle fruiting bodies form underground and emit a variety of volatile organic compounds (VOCs). Truffle volatiles are believed to have evolved to attract animals that disperse their spores. The main VOCs identified from truffles include sulfur compounds, such as dimethyl sulfide (DMS) and dimethyl disulfide (DMDS); in addition, 1-octen-3-ol and 2-methyl-1-propanol have been found in most truffle species. Humans use pigs and dogs trained to detect truffle VOCs in order to find these prized subterranean macrofungi. Truffles have pharmacological potential, but until more reliable cultivation methods become available their high price means they are unlikely to see widespread use as medicinals.     

Eine diözische Flechte

The lichenLecidea verruca, growing parasitically on other crustaceous lichens, is, contrary to most other lichenized ascomycetes, dioecious. The male thalli bearing spermogonia are mostly smaller than the female ones.

     

Book review

Summary

A new coprophilous species of Coniochaeta, C. burtii, with 512-spored asci, is described from deer dung from Glen Dochart, Perthshire.     

A Review of the Biology and Pathogenicity of Rosellinia necatrix– The Cause of White Root Rot Disease of Fruit Trees and Other Plants

Rosellinia necatrix, an ascomycete soil‐inhabiting fungus, causes white root rot disease in a large number of plant species, especially fruit trees. The fungus, which occurs worldwide, is very aggressive and can kill infected trees. The biology and pathogenicity of the fungus are reviewed here, together with the current principal methods of disease control used in different pathosystems.     

Effect of disturbances on the genetic diversity of an old-forest associated lichen

Lichens associated with old forest are commonly assumed to be negatively affected by tree logging or natural disturbances. However, in this study performed in a spruce-dominated sylvopastoral landscape in the Swiss Jura Mountains, we found that genetic diversity of the epiphytic old-forest lichen Lobaria pulmonaria depends on the type of disturbance. We collected 923 thalli from 41 sampling plots of 1 ha corresponding to the categories stand-replacing disturbance (burnt), intensive logging (logged) and uneven-aged forestry (uneven-aged), and analysed the thalli at six mycobiont-specific microsatellite loci. We found evidence for multiple independent immigrations into demes located in burnt and logged areas. Using spatial autocorrelation methods, the spatial scale of the genetic structure caused by the clonal and recombinant component of genetic variation was determined. Spatial autocorrelation of genotype diversity was strong at short distances up to 50 m in logged demes, up to 100 m in uneven-aged demes, with the strongest autocorrelation up to 150 m for burnt demes. The spatial autocorrelation was predominantly attributed to clonal dispersal of vegetative propagules. After accounting for the clonal component, we did not find significant spatial autocorrelation in gene diversity. This pattern may indicate low dispersal ranges of clonal propagules, but random dispersal of sexual ascospores. Genetic diversity was highest in logged demes, and lowest in burnt demes. Our results suggest that genetic diversity of epiphytic lichen demes may not necessarily be impacted by stand-level disturbances for extended time periods.     

Isolation and characterization of microsatellite markers for the tree-root endophytes Phialocephala subalpina and Phialocephala fortinii s.s

Species of the Phialocephala fortinii s.l.-Acephala applanata complex are the dominant dark septate endophytes (DSE) in roots of species belonging to the Pinaceae. The two species Phialocephala subalpina and P. fortinii s.s. belong to the most widely distributed species within this complex. In the present study, 15 polymorphic microsatellite loci were developed for these two closely related species. Strains of a community which were analysed previously using single-copy restriction fragment length polymorphism were screened with the new markers. Microsatellites were suitable to classify the two species and to recognize individuals within species.