Patterns of hybridization and population genetic structure in the terrestrial orchids Liparis kumokiri and Liparis makinoana (Orchidaceae) in sympatric populations

We investigated the potential for gene flow and genetic assimilation via hybridization between common and rare species of the terrestrial orchid genus Liparis, focusing specifically on sympatric and allopatric populations of the common Liparis kumokiri and the rare Liparis makinoana. We utilized analyses of genetic diversity, morphology, and the spatial distributions of individuals and genotypes to quantify the dynamics of interspecific gene flow at within- and among-population scales. High levels of allozyme genetic diversity (HE) were found in populations of the rare L. makinoana (0.317), whereas the common L. kumokiri (N = 1744 from 14 populations) revealed a complete lack of variation. This contrast may reflect different breeding systems and associated rates of genetic drift (L. makinoana is self-incompatible, whereas L. kumokiri is self-compatible). At the two known sympatric sites, individuals were found that recombined parental phenotypes, possessing floral characteristics of L. kumokiri and vegetative characteristics of L. makinoana. These putative hybrids were the only individuals found segregating alleles diagnostic of both parental species. Analysis of these individuals indicated that hybrid genotypes were skewed towards L. kumokiri and later generation recombinants of L. kumokiri at both sympatric sites. Furthermore, Ripley's bivariate L(r) statistics revealed that at one site these hybrids are strongly spatially clustered with L. kumokiri. Nonetheless, the relatively low frequency of hybrids, absence of ongoing hybridization (no F1s or first generation backcrossess), and strong genetic differentiation between morphologically 'pure' parental populations at sympatric sites (FST = 0.708-0.816) indicates that hybridization was not an important bridge for gene flow. The results from these two species suggest that natural hybridization has not played an important role in the diversification of Liparis, but instead support the view that genetic drift and limited gene flow are primarily responsible for speciation in Liparis. Based on genetic data and current status of the species, implications of the research for conservation are considered to provide guidelines for appropriate conservation and management strategies.     

Limitations on orchid recruitment: not a simple picture

Mycorrhizal fungi have substantial potential to influence plant distribution, especially in specialized orchids and mycoheterotrophic plants. However, little is known about environmental factors that influence the distribution of mycorrhizal fungi. Previous studies using seed packets have been unable to distinguish whether germination patterns resulted from the distribution of appropriate edaphic conditions or the distribution of host fungi, as these cannot be separated using seed packets alone. We used a combination of organic amendments, seed packets and molecular assessment of soil fungi required by three terrestrial orchid species to separate direct and indirect effects of fungi and environmental conditions on both seed germination and subsequent protocorm development. We found that locations with abundant mycorrhizal fungi were most likely to support seed germination and greater growth for all three orchids. Organic amendments affected germination primarily by affecting the abundance of appropriate mycorrhizal fungi. However, fungi associated with the three orchid species were affected differently by the organic amendments and by forest successional stage. The results of this study help contextualize the importance of fungal distribution and abundance to the population dynamics of plants with specific mycorrhizal requirements. Such phenomena may also be important for plants with more general mycorrhizal associations.     

Comparison of foliar terpenes between native and invasive Solidago gigantea

To test a defensive chemistry prediction of the Evolution of Increased Competitive Ability (EICA) hypothesis, Solidago gigantea plants from North American and European (invasive) populations were grown in a screen-enclosed garden. Terpenes from 80 seed grown (dried leaves) and 320 rhizome propagated (moist leaves) individuals were confirmed by GC/MS and quantified by GC-FID. Native seed grown plants were found to have significantly greater diterpene concentrations than their European counterparts; foliar sesquiterpenes did not differ. The occurrence of specific sesquiterpenes and diterpenes was homogeneous across the two seed sources suggesting these biochemical pathways remain unchanged. Leaves from native rhizome propagated plants also had significantly greater monoterpene and diterpene concentrations; again sesquiterpene levels did not differ. Rhizome propagated plants exhibited significant population differences in monoterpene and diterpene concentrations. These data support the defensive chemistry predictions of the EICA hypotheses but cannot discount the role of possible founder effects in the invasive range.     

海南兰科植物新资料

报道了中国兰科Orchidaceae植物一新记录属和3个中国新记录种及5个海南新记录种。其中小囊兰属Micropera Lindl．、红花小囊兰Microperapoilanei（Guill.）Garay、疏花羊耳蒜Liparis sparsiflora Aver.和美丽云叶兰Nephelaphyllum pulchrum Bl.为中国新记录;平卧曲唇兰Panisea cavalerei Schltr．、云南曲唇兰Panisea yunnanensis S．C．Chen＆Z．H．Tsi、束花石斛Dendrobium chrysanthum Wallichex Lindl．、滇南翻唇兰Hetaeria rubens （Lindl．）Benth．ex J．D．Hook．f和毛叶芋兰Nervilia plicata（Andrews）Schltr．为海南新记录种。     

秀雅羊耳蒜,中国羊耳蒜属(兰科)一新记录种

报道了兰科羊耳蒜属一新记录种——秀雅羊耳蒜(Liparis elegans Lindl.),并提供了详细的形态描述和照片。本种与近缘种细茎羊耳蒜(L. condylobulbon Rchb. f.)和L. parviflora (Blume) Lindley的区别是:卵状假鳞茎较短,花序直立,花不倒置,花梗和子房较短等。     

曲唇羊耳蒜在中国东北分布的真实性研究

曲唇羊耳蒜分布于日本、朝鲜和俄罗斯远东地区,中国东北的黑龙江、吉林和辽宁也有报道,但是《中国植物志》认为,该种在中国东北是否存在尚有很大的疑问。本研究证明曲唇羊耳蒜的确在中国东北有分布。     

沫蝉的病原真菌新种——巨孢虫疫霉

在浙江省百山祖自然保护区虫生真菌调查中发现松树上的菱沫蝉(Agrophora sp.)的新病原真菌一种,因其分生孢子远大于任何已知种虫疫霉,故定为新种巨孢虫疫霉(Eryniagigantea Li,Chert et Xu)。其初生分生孢子长倒拟卵形或拟纺锤形,对称或略弯曲,42.6—76.7×l 2.3—26.0μm(平均57.6×l 8.6μm),长径比2.2—4.9(平均3.1);顶稍圆或尖削;基部乳突略钝,有时有孢领。次生分生孢子倒拟卵形至广倒拟卵形;毛管分生孢子未见。假根成束。假囊状体及休眠孢子未见。     

NEW MATERIALS OF DINOCROCUTA GIGANTEA FOUND IN FUGU COUNTY, SHAANXI PROVINCE

Theskullisverybigandrobust,exceptionallyshortandwidthinproperty.Theroofascendslikeaflightofsteps.Occipitalistriangleinformandupperborderextendsposteriorly,projectedovertheoccipital.Theanteriorpartofupperpremolariswiderthanthatofposteriorone.TheprotoconeofP4isverysmall.LengthofM,islongerthanthatofP4.ItslimbswerediscoveredforfirsttimeinChina.Itisshownafterstudyingthatitsskullisexceptionallyrobustbutitslimbsdonotindicateanyrobust.ComparedwiththeHyaenasinensis,theskullofDinocrocutagiganteaisl.…     

Effectiveness and technological feasibility of bioherbicide candidates for biocontrol of Green Foxtail (Setaria viridis)

Green foxtail (Setaria viridis), one of the most common and troublesome weeds worldwide, is becoming very difficult to manage because of the lack of registered herbicides and the appearance of herbicide-resistant populations. Among the new and possible environment-friendly strategies, the use of biological control methods seems to have potential. Drechslera gigantea, Exserohilum rostratum and Exserohilum longirostratum have previously proved to be promising bioherbicide agents against several grass weeds in field trials. While previous studies have established the susceptibility of S. viridis under greenhouse conditions, so far no attempt has been made to establish the effectiveness and feasibility of these fungi as bioherbicides for green foxtail. When spore suspensions were applied as foliar sprays to green foxtail seedlings in a greenhouse, all three fungi caused severe damage by 1 day after application, and seedlings in most cases died within 1 week. The fungi were compatible with several agro-chemicals and host specific when tested against major vegetable crop species grown in the Mediterranean. The demonstrated technological feasibility of producing large amounts of quickly germinable conidia (i.e., asexual spores) on inexpensive solid media increases the potential of these fungi to be used as bioherbicides.