Serpula himantioides is a globally distributed saprotrophic fungus that is observed on all continents except Antarctica (Carlsen et al., 2011).Serpula himantioides mainly occurs on hardwood and softwood trees in natural environments, but it can also inhabit wooden structures (Carlsen et al., 2011). Brown rot caused by S. himantioides in the roots and stem base has been reported on various hosts (e.g. Pseudotsuga menziesii, Larix kaempferi) (Seehann, 1986). In Japan, the butt rot caused by S. himantioides has been reported in old stands of Chamaecyparis pisifera (Haraguchi et al., 2017, Figure 1a-c) and Abies sachalinensis. Molecular analyses have revealed that S. himantioides includes several cryptic lineages. Kauserud et al. (2004) conducted a phylogenetic analysis based on the internal transcribed spacer (ITS) region and the beta-tubulin (tub) gene and identified two lineages. In a follow-up study, Kauserud et al. (2006) performed a phylogenetic analysis based on four DNA regions [ITS, LSU, tub, and the heat stress protein gene (hsp)] with amplified fragment length polymorphisms (AFLPs) and defined three lineages. This study also showed that these three lineages are mutually incompatible, suggesting that they could be defined as biological species. Carlsen et al. (2011) similarly conducted phylogenetic analyses based on the same four DNA regions with additional samples from different regions around the world, Japan excluded, and concluded that S. himantioides consists of five cryptic lineages (PS1-PS5). In the study of Kauserud et al. (2004), a Japanese isolate used in the phylogenetic analysis based on the ITS region clustered with an
Evaluation of GerminationPromoting Treatments for Toxicodendron vernicifluum Seeds Based on Breaking Physical and Physiological Seed Dormancy. J Jpn For Soc 104: 254-261 The seeds of Toxicodendron vernicifluum are considered to be in a state of combinational dormancy, which is a combination of physical and physiological dormancy. To improve the germination rate of T. vernicifluum seeds, the methods reported to be effective in promoting seed germination were evaluated separately for breaking physical and physiological seed dormancy. The most effective methods for breaking physical dormancy of T. vernicifluum seeds were soaking in concentrated sulfuric acid (H 2 SO 4 ) for 60 to 120 min or partial removal of the endocarp. Water absorption was observed to begin at two locations on the seed after soaking in H 2 SO 4 for 90 min. Cold stratification for 4 to 12 weeks was effective in breaking physiological dormancy of the seeds after soaking in H 2 SO 4 . However, seeds treated with cold stratification after partial removal of endocarp did not germinate. The germination rate of seeds soaked in H 2 SO 4 for 90 min followed by 8 weeks of cold stratification (73.2±2.7%)was significantly higher than that of seeds soaked in H 2 SO 4 or cold stratification alone (0.8±1.0% and 0.4±0.9%, respectively) or no treatment (0.0±0.0), indicating that the combined treatment would be effective for improving T. vernicifluum germination.
To explore diversity in cold hardiness mechanisms, high resolution
magnetic resonance imaging (MRI) was used to visualize freezing
behaviors in wintering flower buds of Daphne kamtschatica var.
jezoensis, which have no bud scales surrounding well-developed
florets. MRI images showed that anthers remained stably supercooled to
-14 ∼ -21°C or lower whilst most other tissues froze by -7°C. Freezing
of some anthers detected in MRI images at ∼ -21°C corresponded with
numerous low temperature exotherms and also with the “all-or-nothing”
type of anther injuries. In ovules/pistils, only embryo sacs remained
supercooled at -7°C or lower, but slowly dehydrated during further
cooling. Cryomicroscopic observation revealed ice formation in the
cavities of calyx tubes and pistils but detected no ice in embryo sacs
or in anthers. The distribution of ice nucleation activity in floral
tissues corroborated the tissue freezing behaviors. Filaments likely
work as the ice blocking barrier that prevents ice intrusion from
extracellularly frozen calyx tubes to connecting unfrozen anthers.
Unique freezing behaviors were demonstrated in Daphne flower
buds: preferential freezing avoidance in male and female gametophytes
and their surrounding tissues (by stable supercooling in anthers and by
supercooling with slow dehydration in embryo sacs) whilst the remaining
tissues tolerate extracellular freezing.
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