Fertile sporophore production of Typhula phacorrhiza in the field is related to temperatures near freezing.
Two field tests and one lab test were conducted to examine the environmental factors affecting sporophore production in Typhula phacorrhiza and to compare these results with those documented for T. ishikariensis and T. incarnata. In the 2001 lab test where lighting, soil moisture, and soil-sand media were tested in 50 mL screw-cap tubes incubated at 4 degrees C, the limiting factor for Typhula sporophore production was found to be moisture. In the fall 2001 field test, 100 sclerotia of six isolates from three Typhula spp. were placed into pots filled with a sand and soil mixture. The pots were monitored weekly, and maximum sporophore production for all six isolates and for watered and unwatered pots was observed at 11 weeks, which was soon after mean daily temperatures fell below 0 degrees C. In the second field test in fall 2003, five isolates of the three species were tested with similar procedures, but peak sporophore production was observed after 6 weeks, and again only after mean daily temperatures fell below 0 degrees C. In the field, sporophore production of T. phacorrhiza seems to require the same environmental cues as those of T. ishikariensis or T. incarnata, namely high moisture and temperatures near freezing.
Ecology and Physiology
The subnivean environment represents a habitat of snow mold fungi where their resources, i.e., living plant tissues, are limited and do not increase. The fungi have adopted two major contrasting life history strategies in terms of resource utilization: facultative snow mold fungi can become abundant even without snow cover, and obligate snow mold fungi require snow cover for activity. Some obligate snow mold fungi particularly ascomycetes share plant tissues with other genotypes of the same species and coexist, while basidiomycetous obligate snow mold fungi often exclude even other genotypes of the same species and monopolize resources by individualism. The duration of snow cover is, of course, critical to snow mold fungi for survival and propagation, but the beginning of persistent snow cover and its end are other important issues. Snow mold fungi developed diverse life history strategies to adapt to the predictability of snow cover, which is typically represented by the germination rate and the size of sclerotia. Snow mold fungi also exhibit diverse metabolic reactions to tolerate freezing stress by producing antifreeze proteins, exhibiting osmophily, and altering fatty acid composition. Some snow mold fungi protect themselves from freezing by colonizing deeper into plant tissues.
Genetics of the phenotypic evolution in sheep: a molecular look at diversity-driving genes
Background After domestication, the evolution of phenotypically-varied sheep breeds has generated rich biodiversity. This wide phenotypic variation arises as a result of hidden genomic changes that range from a single nucleotide to several thousands of nucleotides. Thus, it is of interest and significance to reveal and understand the genomic changes underlying the phenotypic variation of sheep breeds in order to drive selection towards economically important traits. Review Various traits contribute to the emergence of variation in sheep phenotypic characteristics, including coat color, horns, tail, wool, ears, udder, vertebrae, among others. The genes that determine most of these phenotypic traits have been investigated, which has generated knowledge regarding the genetic determinism of several agriculturally-relevant traits in sheep. In this review, we discuss the genomic knowledge that has emerged in the past few decades regarding the phenotypic traits in sheep, and our ultimate aim is to encourage its practical application in sheep breeding. In addition, in order to expand the current understanding of the sheep genome, we shed light on research gaps that require further investigation. Conclusions Although significant research efforts have been conducted in the past few decades, several aspects of the sheep genome remain unexplored. For the full utilization of the current knowledge of the sheep genome, a wide practical application is still required in order to boost sheep productive performance and contribute to the generation of improved sheep breeds. The accumulated knowledge on the sheep genome will help advance and strengthen sheep breeding programs to face future challenges in the sector, such as climate change, global human population growth, and the increasing demand for products of animal origin.