Genetic variation in nuclear and mitochondrial markers supports a large sex difference in lifetime reproductive skew in a lekking species

Sex differences in skews of vertebrate lifetime reproductive success are difficult to measure directly. Evolutionary histories of differential skew should be detectable in the genome. For example, male‐biased skew should reduce variation in the biparentally inherited genome relative to the maternally inherited genome. We tested this approach in lek‐breeding ruff (Class Aves, Philomachus pugnax) by comparing genetic variation of nuclear microsatellites (θ_n; biparental) versus mitochondrial D‐loop sequences (θ_m; maternal), and conversion to comparable nuclear (N_e) and female (N_ef) effective population size using published ranges of mutation rates for each marker (μ). We provide a Bayesian method to calculate N_e (θ_n = 4N_eμ_n) and N_ef (θ_m = 2N_efμ_m) using 95% credible intervals (CI) of θ_n and θ_m as informative priors, and accounting for uncertainty in μ. In 96 male ruffs from one population, N_e was 97% (79–100%) lower than expected under random mating in an ideal population, where N_e:N_ef = 2. This substantially lower autosomal variation represents the first genomic support of strong male reproductive skew in a lekking species.     

RTA2, a novel gene involved in azole resistance in Candida albicans

Widespread and repeated use of azoles, particularly fluconazole, has led to the rapid development of azole resistance in Candida albicans. Overexpression of CDR1, CDR2, and CaMDR1 has been reported contributing to azole resistance in C. albicans. In this study, hyper-resistant C. albicans mutant, with the above three genes deleted, was obtained by exposure to fluconazole and fluphenezine for 28 passages. Thirty-five differentially expressed genes were identified in the hyper-resistant mutant by microarray analysis; among the 13 up-regulated genes, we successfully constructed the rta2 and ipf14030 null mutants in C. albicans strain with deletions of CDR1, CDR2 and CaMDR1. Using spot dilution assay, we demonstrated that the disruption of RTA2 increased the susceptibility of C. albicans to azoles while the disruption of IPF14030 did not influence the sensitivity of C. albicans to azoles. Meanwhile, we found that ectopic overexpression of RTA2 in C. albicans strain with deletions of CDR1, CDR2 and CaMDR1 conferred resistance to azoles. RTA2 expression was found elevated in clinical azole-resistant isolates of C. albicans. In conclusion, our findings suggest that RTA2 is involved in the development of azole resistance in C. albicans.     

Lack of intraspecific variation in cpDNA in Trichocolea tomentella

Abstract

The Asian genus Struckia Müll.Hal. is reduced to a synonym of Plagiothecium Bruch &; Schimp. according to a phylogenetic analysis involving S. argentata (Mitt.) Müll.Hal., S. enervis (Broth.) Ignatov, T.J.Kop. &; D.G.Long and 13 representative boreal species of Plagiothecium. Two nuclear regions, ITS and partial gapC, and five chloroplast regions, rbcL, rps4-trnS, psaB, trnG and trnL-F, were utilized to reconstruct the phylogenetic relationship between Struckia and Plagiothecium. Bayesian, maximum parsimony, and maximum likelihood analyses resulted in a strongly supported clade including Struckia and Plagiothecium. Plagiothecium handelii Broth. and P. paleaceum (Mitt.) A.Jaeger, which share similar geographical ranges with Struckia and intermediate morphological traits between Struckia and Plagiothecium, grouped with the Chinese Struckia, and all of them appeared as sister to the ‘core’ of Plagiothecium. The accurate position of P. piliferum (Sw.) Schimp. remains unclear due to moderate support from all analyses, and we suggest that it is retained in Plagiothecium until further evidence is available.     

Occurrence of yeasts in psittacines droppings from captive birds in Italy

Three-hundred twenty five droppings from parrots raised in the premises of 4 breeders and in several private households were cultured for yeasts. One-hundred sixty droppings (49.2%) resulted positive. From these specimens 212 isolates belonging to 27 different species were obtained. Mainly Candida species such as C. albicans, C. catenulata, C. curvata, C. famata, C. glabrata, C. guilliermondi, C. holmii, C. intermedia, C. krusei, C. lambica, C. lusitaniae, C. membranaefaciens, C. parapsilosis, C. pelliculosa, C. sake and C. valida were isolated. Debaryomyces marama, D. polymorphus, Geotrichum sp., Pichia etchelsii, P. ohmeri, Rhodotorula glutinis, R. rubra, Rhodotorula sp., Saccharomyces cerevisiae, S. kluyiveri and Zygosaccharomyces sp. were also obtained. Dark colonies on Staib medium were never observed. The psittacine birds apparently serve as carriers for several Candida species or their perfect states and to a lesser extent for other opportunistic yeasts such as Rhodotorula, Trichosporon and Saccharomyces spp., which are considered part of the transient microbiota of the gastrointestinal tract. The most striking finding was the absence of Cryptococcus spp. among the isolates. The present survey confirms the role of pet birds in carrying potential zoonotic yeasts. This revised version was published online in June 2006 with corrections to the Cover Date.     

Application of desmid diversity in assessing the water quality of 12 freshwater resources in Thailand

Desmids from 12 freshwater resources in the northern part of Thailand were investigated during 2002 to 2003. A total of 91 taxa were found. They belonged to 17 genera: Actinotaenium, Spirotaenia, Netrium, Gonatozygon, Pleurotaenium, Closterium, Euastrum, Micrasterias, Cosmarium, Cosmocladium, Stuarastrum, Staurodesmus, Xanthidium, Teilingia, Spondylosium, Hyalotheca and Desmidium. The water qualities in all the water resources were classified as oligotrophic to meso-eutrophic by trophic status. The taxa that could possibly be used as bioindicators of trophic state were Staurastrum gutwinskii, Spondylosium pandurifoemae, Cosmarium capitulum, C. mediosrobiculatum var. egranutum, S. tortum, Closterium gracile var. elongatum, C. kuetzingii and Closterium dianae var. dianae. The most frequently found taxa were Staurastrum limneticum var. burmense, S. tetracerum var. tetraerum, Pleurotaenium trabecula, Closterium ehrenbergii var. ehrenbergii and C. kuetzingii. The rare taxa in this study were Actinotaenium sp. Spirotaenia condensata, Pleurotaenium burmense var. dacchense and Micrasterias apiculata. Forty-one taxa of desmids were identified as new records for Thailand. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Climate-driven changes in biomass allocation in pines

Future increases in air temperature resulting from human activities may increase the water vapour pressure deficit (VPD) of the atmosphere. Understanding the responses of trees to spatial variation in VPD can strengthen our ability to predict how trees will respond to temporal changes in this important variable. Using published values, we tested the theoretical prediction that conifers decrease their investment in photosynthetic tissue (leaves) relative to water‐conducting tissue in the stem (sapwood) as VPD increases. The ratio of leaf/sapwood area (A_L/A_S) decreased significantly with increasing VPD in Pinus species but not in Abies, Pseudotsuga, Tsuga and Picea, and the average A_L/A_S was significantly lower for pines than other conifers (pines: 0.17 m² cm^?2; nonpines: 0.44 m² cm^?2). Thus, pines adjusted to increasing aridity by altering above‐ground morphology while nonpine conifers did not. The average water potential causing a 50% loss of hydraulic conductivity was ?3.28 MPa for pines and ?4.52 MPa for nonpine conifers, suggesting that pines are more vulnerable to xylem embolism than other conifers. For Pinus ponderosa the decrease in A_L/A_S with high VPD increases the capacity to provide water to foliage without escalating the risk of xylem embolism. Low A_L/A_S and plasticity in this variable may enhance drought tolerance in pines. However, lower A_L/A_S with increasing VPD and an associated shift in biomass allocation from foliage to stems suggests that pines may expend more photosynthate constructing and supporting structural mass and carry less leaf area as the climate warms.     

Negative inbreeding effects in tree fruit breeding: self-compatibility transmission in almond

Inbreeding depression has been observed in most fruit trees, negatively affecting the offspring of related parents. This problem is steadily increasing due to the repeated utilization of parents in breeding programmes. In almond, self-compatibility transmission from ‘Tuono’ to its offspring remains partially unexplained due to deviations from the expected genotype ratios. In order to test if these deviations could be due to inbreeding, the S-genotypes of the seedlings of four almond families, ‘Tuono’ (S ₁ S _f ) × ‘Ferragnès’ (S ₁ S ₃ ), ‘Tuono’ (S ₁ S _f ) × ‘Ferralise’ (S ₁ S ₃ ) and reciprocal crosses were studied. The S-genotype determination of each seedling by separation of stylar S-RNases and by S-allele-specific PCR amplification gave identical results. The ratio of S-genotypes of the family ‘Tuono’ × ‘Ferralise’ was the one least adjusted to the expected 1:1 ratio, because the number of self-compatible seedlings (S _f S ₃ ) was less than a half the number of self-incompatible ones (S ₁ S ₃ ). A mechanism acting against inbreeding would favour cross-breeding in the following generation to increase heterozygosity. This fact stresses the need to avoid crosses between related parents in fruit breeding programmes.     

Soil respiration in six temperate forests in China

Scaling soil respiration (R_S), the major CO₂ source to the atmosphere from terrestrial ecosystems, from chamber‐based measurements to ecosystems requires studies on variations and correlations of R_S from various biomes and across geographic regions. However, few studies on R_S are available for Chinese temperate forest despite the importance of this forest in the national and global carbon budgets. In this study, we conducted 18‐month R_S measurements during 2004–2005 in six temperate forest types, representing the typical secondary forest ecosystems across various site conditions in northeastern China: Mongolian oak (Quercus mongolica Fisch.), aspen‐birch (Populous davidiana Dode and Betula platyphylla Suk.), mixed deciduous (no dominant tree species), hardwood (dominated by Fraxinus mandshurica Rupr., Juglans mandshurica Maxim., and Phellodendron amurense Rupr.) forests, Korean pine (Pinus koraiensis Sieb. et Zucc.) and Dahurian larch (Larix gmelinii Rupr.) plantations. Our specific objectives were to: (1) explore relationships of R_S against soil temperature and water content for the six forest ecosystems, (2) quantify annual soil surface CO₂ flux and its relations to belowground carbon storage, (3) examine seasonal variations in R_S and related environmental factors, and (4) quantify among‐ and within‐ecosystem variations in R_S. The R_S was positively correlated to soil temperature in all forest types, and was significantly influenced by the interactions of soil temperature and water content in the pine, larch, and mixed deciduous forests. The sensitivity of R_S to soil temperature at 10 cm depth (Q₁₀) ranged from 2.61 in the oak forest to 3.75 in the aspen‐birch forests. The Q₁₀ tended to increase with soil water content until reaching a threshold, and then decline. The annual R_S for the larch, pine, hardwood, oak, mixed deciduous, and aspen‐birch forests averaged 403, 514, 781, 785, 786, and 813 g C m^?2 yr^?1, respectively. The annual R_S of the broadleaved forests was 72% greater than that of the coniferous forests. The annual R_S was positively correlated to soil organic carbon (SOC) concentration at O horizon (R²=0.868) and total biomass of roots <0.5 cm in diameter (R²=0.748). The coefficient of variation (CV) of R_S among forest types averaged 25% across the 18‐month measurements. The CV of R_S within plots varied from 20% to 27%, significantly (P<0.001) greater than those among plots (9–15%), indicating the importance of the fine‐scaled heterogeneity in R_S. This study emphasized that variations in soil respiration and potential sampling bias should be appropriately tackled for accurate soil CO₂ flux estimates.     

酱香型白酒发酵中地衣芽孢杆菌前噬菌体的鉴别

【背景】噬菌体是微生物群落的重要组成部分,但传统白酒发酵中噬菌体的分类和存在尚不清楚。【目的】通过检测公共数据库和酱香型白酒发酵中地衣芽孢杆菌(Bacillus licheniformis)基因组中的前噬菌体整合区域,探究传统酱香型白酒发酵中关键功能菌株的前噬菌体分类和侵染情况。【方法】使用未培养(细菌全基因组分析)和可培养(菌株筛选和特异性PCR反应)技术对不同环境来源和来自酱香型白酒发酵的地衣芽孢杆菌前噬菌体的分类和存在进行解析。【结果】细菌全基因组分析显示,30株来自不同环境的地衣芽孢杆菌基因组中共注释到165个前噬菌体,其中63.6%(105/165)为完整前噬菌体序列。97.1%感染地衣芽孢杆菌的噬菌体属于长尾噬菌体科(Siphoviridae),2.9%属于肌尾噬菌体科(Myoviridae),53.0%完整前噬菌体的基因功能未知。在来自酱香型白酒发酵的B. licheniformis MT-B06中检测到7个前噬菌体整合序列,其中57.1%(4/7)为完整前噬菌体序列,来自酱香型白酒发酵的地衣芽孢杆菌存在多种不同前噬菌体的共感染。来自酱香型白酒发酵的地衣芽孢杆菌前噬菌体存在来自细菌基因组上相邻CotD孢子外壳蛋白(CotD family spore coat protein)基因的水平基因转移。在26株来自酱香型白酒发酵的地衣芽孢杆菌中,69.2%(18/26)存在噬菌体编码主要衣壳蛋白的基因,100.0%(26/26)存在噬菌体编码CotD孢子外壳蛋白的基因。【结论】来自不同环境的地衣芽孢杆菌和酱香型白酒发酵的地衣芽孢杆菌中存在高水平的前噬菌体整合,来自酱香型白酒发酵的地衣芽孢杆菌前噬菌体中广泛存在来源于宿主的CotD孢子外壳蛋白基因的水平基因转移。本研究为首次对传统发酵白酒中噬菌体的分类和存在进行探究,有助于对发酵微生物群落中噬菌体-细菌相互作用加深理解。     

Occurrence of Ochratoxin A-Producing Fungi in Commercial Corn Kernels in Argentina

Potentially ochratoxigenic Aspergillus and Penicillium species were identified and the natural occurrence of ochratoxin A (OTA) in corn kernels was evaluated. Likewise, the capacity to produce OTA by Aspergillus section Nigri and Circumdati was investigated. A total of 50 corn samples for human consumption was collected in the south of Córdoba Province. The surface-disinfected method for mycobiota determination was used. The OTA detection was performed by HPLC. OTA production was tested in strains belonging to section Nigri and Circumdati. Statistical analysis demonstrated that the specie A. flavus was isolated in higher frequency (p<0.01) from corn kernels in DRBC and DG18 media. The percentage of corn kernels contaminated by A. niger var. niger was similar in DRBC and DG18 media. The frequency of grains contaminated by A. flavus and A. niger var. awamori was higher than A. niger var. niger and A. japonicus var. japonicus (p<0.01) in DG18 media. The other potentially ochratoxigenic species, A. ochraceus, was isolated between 5% and 10% of the corn kernels in DG18 and DRBC media, respectively. The OTA producing species P. verrucosum was not isolated. All samples of corn were OTA negative (<1 ng g⁻¹). Thirty strains (25%) of the black Aspergillus were OTA producers. From four strains of A. ochraceus isolated, only one produced OTA. Due to the storage variable conditions could not be adequate in this substrate, the presence of ochratoxigenic strains of section Nigri and OTA needs to be evaluated for a longer time to establish the toxicological risk for human beings. The contamination of stored corn kernels with A. flavus and Aspergillus section Nigri was significant.     

Immune responses in vitro

The Mls locus was originally defined to have four alleles; three controlled products that were detectable in primary mixed leukocyte reactions (MLR), whereas one, b, was described as being null. Recently, other investigators postulated that the Mls locus is nonpolymorphic, being composed of the b null allele and of a singly expressed allele previously thought to be the a and d alleles. We previously reported that products controlled by Mls ^aand Mls ^dwere antigenically distinct and therefore are not controlled by the same allele, and the product of Mls ^bon cells of three different strains was easily detectable by Mls ^aand Mls ^dresponding cells. Thus the b allele is not null. In the present report evidence is presented which indicates that both Mls ^band Mls ^cencoded products were undetectable by MLR when in the presence of Mls ^aor Mls ^d. This was demonstrated by (a) the inability of Mls ^a/Mls ^cand Mls ^a/Mls ^bF₁ cells to stimulate Mls ^aresponding cells and Mls ^d/Mls ^cand Mls ^d/Mls ^bcells to stimulate Mls ^dcells; (b) the positive response of Mls ^a/Mls ^band Mls ^d/Mls ^bF₁-hybrid cells to Mls ^b-encoded products; and (c) the reactivity of Mls ^a/Mls ^cand Mls ^d/Mls ^cF₁ hybrid cells to Mls ^c-encoded determinants.     

Hydraulic conductance and water potential gradients in squash leaves showing mycorrhiza-induced increases in stomatal conductance

Stomatal conductance (g _s) and transpiration rates vary widely across plant species. Leaf hydraulic conductance (k _leaf) tends to change with g _s, to maintain hydraulic homeostasis and prevent wide and potentially harmful fluctuations in transpiration-induced water potential gradients across the leaf (ΔΨ _leaf). Because arbuscular mycorrhizal (AM) symbiosis often increases g _s in the plant host, we tested whether the symbiosis affects leaf hydraulic homeostasis. Specifically, we tested whether k _leaf changes with g _s to maintain ΔΨ _leaf or whether ΔΨ _leaf differs when g _s differs in AM and non-AM plants. Colonization of squash plants with Glomus intraradices resulted in increased g _s relative to non-AM controls, by an average of 27% under amply watered, unstressed conditions. Stomatal conductance was similar in AM and non-AM plants with exposure to NaCl stress. Across all AM and NaCl treatments, k _leaf did change in synchrony with g _s (positive correlation of g _s and k _leaf), corroborating leaf tendency toward hydraulic homeostasis under varying rates of transpirational water loss. However, k _leaf did not increase in AM plants to compensate for the higher g _s of unstressed AM plants relative to non-AM plants. Consequently, ΔΨ _leaf did tend to be higher in AM leaves. A trend toward slightly higher ΔΨ _leaf has been observed recently in more highly evolved plant taxa having higher productivity. Higher ΔΨ _leaf in leaves of mycorrhizal plants would therefore be consistent with the higher rates of gas exchange that often accompany mycorrhizal symbiosis and that are presumed to be necessary to supply the carbon needs of the fungal symbiont.     

Five novel missense mutations of the Lewis gene (FUT3) in African (Xhosa) and Caucasian populations in South Africa

Five novel missense mutations, viz., C304 A, T370 G, G484 A, G667 A, and G808 A, in the Lewis gene (FUT3) were detected in African (Xhosa) and Caucasian individuals in South Africa. These single base substitutions may result in changes in amino acid residues from Gln102 to Lys in the 304 mutation, Ser124 to Ala in the 370 mutation, Asp162 to Asn in the 484 mutation, Gly223 to Arg in the 667 mutation, and Val270 to Met in the 808 mutation. Out of the five novel mutations identified in this investigation, four new alleles (le ^484,667 , le ^484,667,808 , Le ³⁰⁴ , and Le ³⁷⁰ ) were determined in the Xhosa population and two new alleles (le ^202,314,484 and Le ³⁰⁴ ) in the Caucasian population. The determination of α(1,3/1,4)fucosyltransferase activity, after transfection of plasmids containing the new alleles into COS7 cells, suggested that alleles le ^484,667 and le ^484,667,808 encoded an inactive enzyme, and that alleles Le ³⁰⁴ and Le ³⁷⁰ encoded a functional enzyme. In addition, we also examined the incidence of five common alleles, Le ⁵⁹ , le ^59,508 , le ^59,1067 , le ^202,314 , and le ¹⁰⁶⁷ in two populations by the polymerase chain reaction/restriction fragment length polymorphism method and compared differences in the allele frequencies of FUT3 among three ethnic groups (Orientals, Africans, and Caucasians). Received: 19 January 1998 / Accepted: 4 Febraury 1998     

Five novel elements involved in the regulation of mitosis in fission yeast

Summary Five new elements of the mitotic control in the fission yeast Schizosaccharomyces pombe were isolated from gene libraries as multicopy suppressors of the conditional lethal phenotype of win1-1 weel ^ts cdc25^ts triple mutant strains. These genes were designated wisl ⁺ –wis5⁺for win suppressing, and do not correspond to winl ⁺ or any of the previously characterised mitotic control genes. None of the wis genes is capable of suppressing the cdc phenotype of cdc25 ^ts strains, suggesting that their effect is not simply to reverse the effect of loss of cdc25 function. wisl ⁺ has been previously reported to encode a putative serine/threonine protein kinase that acts as a dosage-dependent inducer of mitosis. wis4 ⁺ appears to be a specific suppressor of the winl-1 mutation. wis2 ⁺ and wis3 ⁺ are capable of suppressing a wide range of cdc phenotypes arising from the combination of various mutations with wee1 ^ts and cdc25 ^ts, suggesting that the wis2 ⁺ and wis3 ⁺ products may interact with elements central to the mitotic control.     

Genetics of tolerance to iron chlorosis in rice

Genetics of tolerance to iron chlorosis was investigated in eight crosses involving parents distinctly different in their level of tolerance. The segregating populations with parents and F₁s were screened under actual stress conditions in the field. Also, selected crosses were studied for Fe³⁺ uptake capacity. Tolerance/moderate tolerance to Fe chlorosis was dominant over susceptibility and it was controlled by two sets of nonallelic genes with complementary interaction. Gene Ic ₁ has been found to be basic and in complementation with Ic ₃ it confers tolerance. Likewise, Ic ₂ with Ic ₄ confers tolerance. The basic genes Ic ₁ and Ic ₂ are nonallelic and, in the absence of their respective complementary genes Ic ₃ and ₄ , ineffective, which results in susceptibility. Of tolerant cultivars, ARC 10372 and Cauvery have been tentatively assigned the genotype of Ic ₁ , Ic ₂ , Ic ₃ , Ic ₄ , and moderately tolerant IET 7613, Prasanna and Akashi Ic ₁ , ₂ Ic ₃ Ic ₄ . The susceptible ARC 5723 has been assigned Ic ₁ , ₂ , Ic ₃ , Ic ₄ , and IET 9829, Ic ₁ , ₂ Ic ₃ Ic ₄ . IET 7614 is susceptible, due to the presence of inhibitory genes I-Ic ₁ , I-Ic ₂ together with ic ₁ pt>, ic ₂ , Ic ₃ , Ic ₄ . Further, the gene Pc for purple coleoptile shows linkage with one of the complementary genes with a crossover value of 15.26%, while the gene(s) for seedling height Ts with Ic ₁ with a crossover value of 1.7%. It is possible that the gene(s) for iron chlorosis tolerance might belong to the second linkage group, where genes for purple leaf were located.     

Expression of a Leishmaniadonovani nucleotide sugar transporter in Leishmaniamajor enhances survival in visceral organs

Leishmania donovani and Leishmaniainfantum infections cause fatal visceral leishmaniasis, and Leishmaniamajor causes self healing cutaneous lesions. It is poorly understood what genetic differences between these Leishmania species are responsible for the different pathologies of infection. To investigate whether L.donovani species-specific genes are involved in visceral Leishmania infection, we have examined a L.donovani species-specific gene Ld1590 (ortholog of LinJ15_V3.0900) that is a pseudogene in L.major. We have previously shown that transgenic expression of L.donovani Ld1590 in L.major significantly increased the liver and spleen parasite burdens in infected BALB/c mice. In this study we report that Ld1590 potentially encodes a nucleotide sugar transporter (NST) which localizes in the L.donovani Golgi apparatus. Surprisingly, although transgenic expression of the Ld1590 NST increased L.major survival in visceral organs, deletion of Ld1590 NST in L.donovani had no significant effect on L.donovani survival in mice. These observations suggest that loss of the functional Ld1590 gene in L.major may have been associated with reduced virulence in visceral organs in its animal reservoir and could have contributed to L.major’s tropism for cutaneous infections.     

Facilitation in multiple life-history stages: evidence for nucleated succession in coastal dunes

Garden experiments focused on vegetative regeneration were carried out with four invasive taxa of the genus Reynoutria (R. japonica var. japonica, R. japonica var. compacta, R. sachalinensis and a hybrid between R. sachalinensis and R. japonica var. japonica, R. ×bohemica). Regeneration ability of stems and rhizomes, timing of shoot emergence and biomass production were studied under the following treatments: laid horizontally on the soil surface; placed upright; buried in the soil; floating in water. Two different soils (sand and garden loam) representing contrasting nutrient levels were applied. Differences were found in the capability and speed of regeneration, as well as in the quality of shoots produced. Regeneration from stems was less efficient than that from rhizomes in all taxa except R. sachalinensis. R. ×bohemica exhibits higher regeneration potential (61%) than all other taxa and can be considered as the most successful taxon of the Czech representatives of the genus Reynoutria in terms of regeneration and establishment of new shoots. High regeneration capacity was also exhibited by R. japonica var. compacta (52%). Other taxa showed generally lower regeneration rates (R. japonica var. japonica 39% and R. sachalinensis 21%), but under some treatments the percentage of regenerated segments was high, too. R. japonica var. japonica rhizomes regenerated successfully in all three soil treatments but not in the water. An opposite pattern was found for its stems: they regenerated well if exposed to water treatment but in the soil, they did not regenerate at all. Particular taxa responded to the soil type in a contrasting way. R. sachalinensis and R. ×bohemica regenerated better in loam while the opposite was true in R. japonica var. japonica. R. japonica var. compacta produced the tallest and R. ×bohemica the heaviest and most robust shoots. It is concluded that rhizomes are more crucial than stems for the spread of knotweeds through fragmentation and clonal growth, suggesting the importance of soil disturbance.