Bambusicolous fungi in Japan (5): three species of Tetraploa

Three species of Tetraploa collected from Sasa, or bamboos, are described and illustrated. Among them, T. curviappendiculata on Sasa kurilensis and T. longissima on Pleioblastus chino are compared with hitherto known species and described as new species. In the nomenclature, T. javanica is substituted for T. biformis, formerly reported from the dead bark of a broad-leaved tree in Japan, as a correct name.     

Preliminary investigation on iodine nutrition in captive giant pandas

Background/ObjectiveThe giant panda belongs to the family Ursidae and, as a species of bear, still retains the simple digestive system of a Carnivoran. However, under the pressure of a specific habitat they had to adapt to a plant mono-diet consisting of bamboo with different species and growth stages around the year. A plant-based diet has relatively low iodine content with risk of iodine deficiency. Furthermore, bamboo contains cyanogenic glycosides releasing cyanide whose detoxification metabolite the thiocyanate acts as antagonist against iodine uptake and storage in the thyroid. To date very little is known about the iodine nutritional status of the giant panda, thus this study was conducted to receive the first information about the iodine nutrition of captive giant panda.Subjects/MethodsHere we investigated the iodine content of bamboo with different plant parts/vegetation stage and species and further compounds of the captive giant panda diet. Next, the urinary iodine (UI) and urinary thiocyanate (UT) levels of infant, sub-adult, adult and geriatric captive giant pandas was measured during the periods when the pandas consume both bamboo leaves- and culm (bamboo leaf-culm stage). Afterwards, the UI of 19 adult giant pandas was measured again for the different iodine intake during bamboo shoot stage. Finally, in this study part also the fecal iodine concentration was analyzed for calculation of total iodine excretion in relation to the iodine intake.ResultsBamboo leaves had the highest iodine content (453 μg/kg dry matter (DM)), followed by the shoots (84 μg/kg DM, p < 0.05), while bamboo culm had the lowest value (12 μg/kg DM, p < 0.05). During bamboo leaf-culm stage, giant pandas of different age groups had different UI and UT levels (p < 0.05). Furthermore, UI and UT were positively correlated among sub-adult, adult and geriatric giant pandas (p < 0.05). In adult giant pandas during bamboo shoot stage, the iodine excretion in feces was not different from that in urine while their total iodine excretion was less than their iodine intake (p < 0.05). Moreover, during bamboo shoot stage, the UI level of adult giant pandas was much lower than noted during bamboo leaf-culm stage (p < 0.05).ConclusionsOur results indicate that UI of captive giant pandas was related to their age as well as to the vegetation stage/part of bamboo they consumed reflecting a different periodic iodine supply. Thiocyanate and fecal excretion should be emphasized when considering the iodine nutrition of giant pandas.     

苏南丘陵区毛竹林冠截留降雨分布格局

降雨穿过林冠层时,由于林冠的拦截作用,改变了降雨分布格局。林冠截留是一个复杂的水文过程,受降水特征及林分特性的影响较大。本文以北亚热带苏南丘陵地区人工毛竹林(Phyllostachys edulis)为研究对象,利用2007年度各场次降雨观测数据,分析了降雨量和降雨强度与林冠截留降雨的关系,研究了林冠截留过程的特点。结果表明：（1） 研究期间共观测到102次降水事件,降水总量为1110.8mm,单次最大降雨量为110.0㎜,最小为0.55㎜,事件平均降水量为10.89mm,且绝大部分降雨为低雨强、中雨量级的降雨事件。（2） 研究期间林冠截留总量为171.72mm,占同期降雨总量的15.46%。单次林冠截留量变幅为0.21—4.55mm,截留率变幅为1.3%—100%,且随林外降雨量的递增,林冠截留率呈现递减的变化趋势,二者的关系用幂函数（I0=117.34P-0.9106）拟合效果较好。（3）在林外次降雨量小于5㎜的条件下,事件降雨量占年降雨总量的5.0%,相应的降雨事件频率为9.8%,此时林冠截留量随降雨量的增大而增加,其变幅为0.55—1.9㎜,截留量与降雨量的关系用对数函数（I=0.4931Ln(P) 0.9493）进行拟合效果较好;在单场降雨量大于5㎜时,林冠截留量随各场次降雨量的增加,其变动幅度和频率均大大增强,变化范围在0.21—4.55㎜之间,二者相关性较差。（4）降雨在7—10mm雨量级范围内时,林外降雨量和林冠截留量分别为245.14mm和47.9㎜,占其全年总量的比例均为最大,分别为22.07%和27.9%;各雨量级林冠平均截留量与平均降雨量的关系表现为对数函数关系（R2=0.7287）,而截留率与平均降雨量的关系表现为极显著的幂函数关系（R2=0.9817）,且林冠对降雨的截留作用在雨量级较小时,表现十分显著。（5）全年单场降雨强度小于0.06mm/min时,降雨事件频数为73.53%,降雨量占其总量的57.93%,林冠截留量占其总量的89.34%,降雨事件平均截留率（23.84%）远高于雨强大于0.06mm/min时的降雨事件平均截留率（3.92%）。本研究结果为长江中下游丘陵山区水土保持林和水源涵养林体系建设提供了理论依据。     

The Effect of Bamboo Charcoal Application on Soil Nutrients and Heavy Metals in Rice

Soil heavy metal pollution is becoming more and more serious. Biomass charcoal application can play an important role in alleviating the toxicity of heavy metals in soils. Compared with other biochar, bamboo charcoal has more unique properties and may have a unique effect on heavy metal pollution. Zhejiang Province of Southeastern China is rich in bamboo resources. However, few studies related to bamboo charcoal application for heavy metal remediation in farmland were reported. In this study, four treatments with different amounts of bamboo charcoal application were set up through a field experiment, namely BC0 (no bamboo charcoal application), BC1 (2500 kg⋅ha⁻¹), BC2 (5000 kg⋅ha⁻¹), and BC3 (10000 kg⋅ha⁻¹), and each treatment was replicated three times. The results showed that (1) The application of bamboo charcoal significantly increased the soil pH and organic matter content. Compared with BC0, the pH and organic content of BC3 increased by 7.4% and 17.4% (P < 0.05) respectively. (2) The HCl-extractable Cd content of paddy soil in the BC1 treatment was significantly lower than other treatments (P < 0.05), and decreased by 15.3%, compared with BC0. The soil HCl-extractable Zn and Cu content did not differ significantly between treatments (P > 0.05). (3) With the increase of bamboo charcoal application, the Cd content in rice gradually decreased, the BC3 treatment significantly decreased by 39.0% (P < 0.05), and the Zn and Cu contents in rice did not differ significantly between treatments (P > 0.05), compared with BC0. (4) Soil pH, organic matter and Cd in rice seeds were significantly negatively correlated (P < 0.01). The heavy metal content in rice does not change with the change of heavy metal content with HCl-extractable state in soil. It means bamboo charcoal does not reduce heavy metal content in rice by simply declining the heavy metal content with HCl-extractable state. The mechanism of action is relatively complicated, and further study is needed.     

NbRABG3f,a member of Rab GTPase,is involved in Bamboo mosaic virus infection in Nicotiana benthamiana

The screening of differentially expressed genes in plants after pathogen infection can uncover the potential host factors required for the pathogens. In this study, an up‐regulated gene was identified and cloned from Nicotiana benthamiana plants after Bamboo mosaic virus (BaMV) inoculation. The up‐regulated gene was identified as a member of the Rab small guanosine triphosphatase (GTPase) family, and was designated as NbRABG3f according to its in silico translated product with high identity to that of RABG3f of tomato. Knocking down the expression of NbRABG3f using a virus‐induced gene silencing technique in a protoplast inoculation assay significantly reduced the accumulation of BaMV. A transiently expressed NbRABG3f protein in N. benthamiana plants followed by BaMV inoculation enhanced the accumulation of BaMV to approximately 150%. Mutants that had the catalytic site mutation (NbRABG3f/T22N) or had lost their membrane‐targeting capability (NbRABG3f/ΔC3) failed to facilitate the accumulation of BaMV in plants. Because the Rab GTPase is responsible for vesicle trafficking between organelles, a mutant with a fixed guanosine diphosphate form was used to identify the donor compartment. The use of green fluorescent protein (GFP) fusion revealed that GFP‐NbRABG3f/T22N clearly co‐localized with the Golgi marker. In conclusion, BaMV may use NbRABG3f to form vesicles derived from the Golgi membrane for intracellular trafficking to deliver unidentified factors to its replication site; thus, both GTPase activity and membrane‐targeting ability are crucial for BaMV accumulation at the cell level.     

Effects of growth stage on enzymatic saccharification and simultaneous saccharification and fermentation of bamboo shoots for bioethanol production

Bamboo is a fast-growing renewable biomass that is widely distributed in Asia. Although bamboo is recognised as a useful resource, its utilization is limited and further development is required. Immature bamboo shoots harvested before branch spread were found to be a good biomass resource to achieve a high saccharification yield. The saccharification yield of the shoots increased (up to 98% for immature Phyllostachys bambusoides) when xylanase was used in addition to cellulase. Simultaneous saccharification and fermentation (SSF) processing converted immature shoots of P. bambusoides and Phyllostachys pubescens to ethanol with an ethanol yield of 169 and 139 g kg⁻¹, respectively (98% and 81%, respectively, of the theoretical yields based on hexose conversion) when 12 FPU g⁻¹ enzyme and the yeast Saccharomyces cerevisiae were used.     

Comparative study of liquefaction process and liquefied products from bamboo using different organic solvents

The effects of various solvents, including phenol, ethylene glycol (EG) and ethylene carbonate (EC), and different liquid ratios on the liquefaction of bamboo, have been studied systematically in this paper. The processes were catalyzed by hydrochloride acid at 180 °C in autoclaves for different reaction times. The results show that phenol is the optimum solvent for bamboo liquefaction with a yield up to 99%. The Fourier transform-infrared (FT-IR) analyses of the residues show that cellulose, hemicelluloses and lignin are almost decomposed when using phenol as solvent. The gel permeation chromatography (GPC) results of the liquid products show that the high molecular weight of bamboo decreases significantly to around 1800 g mol⁻¹ after liquefaction. The gas chromatography and mass spectrometry (GC–MS) analysis shows that low boiling point products of liquefied bamboo are similar regardless of the type of solvent used.     

Identification and cross-species amplification of EST derived SSR markers in different bamboo species

The availability of expressed sequence data derived from gene discovery programs became an alternative source of mining simple sequence repeat (SSR) and developing inexpensive genetic markers for the crop improvements. In present study, 10 express sequence tags (EST)-SSR markers were identified from Bambusa oldhamii public sequence data base. Transferability to 25 species of Bambusoideae ranged from 30% to 100%. The number of alleles detected per locus ranged from 2 to 10. All the newly identified SSR markers were found to be moderately to highly polymorphic with an average Polymorphic Information Content (PIC) value of 0.54. As these loci represents transcribed region and recorded high level of cross transferability and reliable amplification across the species, demonstrating the utility of these markers for functional and genetic analyses of bamboo species.     

Somatic embryogenesis and regeneration of plants in the bamboo Dendrocalamus strictus

Somatic embryogenesis leading to plant regeneration has been achieved in the bamboo, Dendrocalamus strictus, by culturing seeds (caryopses) on B₅ basal medium supplemented with 2,4-dichlorophenoxyacetic acid. Callus cultures obtained from the embryonal end of the seeds differentiated chlorophyllous embryoids. On transfer to a germination medium (B₅ liquid, sucrose, indolebutyric acid, and -naphthaleneacetic acid) 40% of the embryoids developed into plantlets. Further development of the plantlets occured on B₅ liquid medium (half strength) + sucrose (1%) + IBA (5 × 10^–7M) + NAA (10^–7M).Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IBA Indolebutyric acid - NAA -naphthaleneacetic acid     

Causal analysis of the invasion of broad-leaved forest by bamboo in Japan

Abstract. In southwestern Tokyo the area covered by bamboo forest has expanded by a factor of 2.7 over the last 26 years. This has mainly been due to bamboo (Phyllostachyspubescens) invading secondary broad-leaved forests, probably after these were abandoned. In the first stage, bamboo sprouts develop from rhizomes at the periphery of the broad-leaved forest and then grow very quickly into young culms. In the next phase culm density increases annually, while the existing broad-leaved trees gradually lose their vitality and die. Finally, the broad-leaved forest is completely replaced by bamboo forest. The competitive ability of bamboo, based on its morphological and growth features, is suggested as the causal factor for the invasion: (1) bamboo can invade a neighboring broad-leaved forest by its vigorous rhizomes; (2) young bamboo culms can break through the canopy of broad-leaved trees; (3) bamboo quickly forms a crown in or above the canopy of the broad-leaved forest; (4) bamboo is very tolerant of strong wind and heavy snow accumulation; (5) bamboo culms, being very pliable during strong wind mechanically damage neighbouring broad-leaved trees.