A new variety of Draba oreibata (Brassicaceae) from Nevada,U.S.A.

A new variety ofDraba oreibata, var.serpentina, is described, illustrated, and discussed.     

Draba longiciliata sp. nov. (Brassicaceae) from Ecuador

Draba longiciliata Al‐Shehbaz & Sklená?, a new species from the Ecuadorian páramo, is described and illustrated. It is readily distinguished from the remaining South American species by a combination of linear leaves, glabrous on both surfaces and long‐ciliate along the entire margin and apex, and by the slender, many‐branched, slightly woody lower stems, densely covered with persistent leaf bases.     

Polyploid origins in a circumpolar complex in Draba (Brassicaceae) inferred from cloned nuclear DNA sequences and fingerprints

Polyploid evolution has been of major importance in the arctic flora, but rarely addressed on the full circumpolar scale. Herein we study the allopolyploid Draba lactea and its close allies, which form a taxonomically intricate arctic-alpine complex including diploids, tetraploids, and hexaploids. Based on samples from the entire circumpolar area, we inferred the origins of polyploids in this complex using cloned DNA sequences from two nuclear regions (one intron from a gene encoding a second largest subunit in the RNA polymerase family, RPD2, and the ribosomal internal transcribed spacer region, ITS) and DNA fingerprints (random amplified polymorphic DNAs, RAPDs). Although D. lactea and all other polyploids examined in Draba are genetic alloploids showing fixed heterozygosity, the data obtained in the present study suggest that each of the polyploids analyzed here may have originated from a single diploid lineage: hexaploid D. lactea via tetraploid D. lactea from the D. palanderiana lineage (not from the D. fladnizensis and D. nivalis lineages as previously hypothesized), the tetraploid D. turczaninovii from the D. fladnizensis lineage, the tetraploid D. porsildii from the D. lonchocarpa lineage, and a tetraploid here named Draba spB from the D. nivalis lineage. Draba lactea has probably originated several times in the Beringian area, and it is not necessary to invoke complex origins based on a combination of different species lineages as previously suggested.     

A new variety of Draba pedicellata and a lectotype for D. cusickii (Brassicaceae)

A closely related group of Great Basin endemic dradas,Draba cusickii O. E. Schulz,D. sphaeroides Payson, andD. pedicellata (Rollins & R. A. Price) Windham, are described, keyed, and discussed in order to putD. pedicellata var.wheelerensis N. H. Holmgren, var. nov. in perspective.Draba cusickii is endemic to Steens Mountain of southeastern Oregon, andD. sphaeroides is known only from three mountain ranges in Elko County, Nevada, whereasD. pedicellata is more widespread in mountain ranges of eastern Nevada in Elko, Eureka, Nye, and White Pine counties.Draba pedicellata var.pedicellata occupies most of the range of the species, with var.wheelerensis being restricted to the Snake Range, just to the east of the range of the typical variety.     

Genetics of intrinsic postzygotic isolation in a circumpolar plant species, Draba nivalis (Brassicaceae)

Sterility barriers, ranging from incomplete to fully developed, were recently demonstrated within taxonomic species of the genus Draba, suggesting the existence of numerous, cryptic biological species. Because these taxa are predominately selfers and of Pleistocene origin, it was concluded that hybrid sterility evolved quickly and possibly by genetic drift. Here we used genetic mapping and QTL analyses to determine the genetic basis of hybrid sterility between geographically distant populations of one of these taxonomic species, Draba nivalis. Fifty microsatellite loci were mapped, and QTL analyses identified five loci underlying seed fertility and two underlying pollen fertility. Four of five seed fertility QTLs reduced fertility in heterozygotes, an observation most consistent with drift-based fixation of underdominant sterility loci. However, several nuclear-nuclear interactions were also found, including two that acted like reciprocal translocations with lowest fitness in double heterozygotes, and two that had a pattern of fitness consistent with Bateson-Dobzhansky-Muller incompatibilities. In contrast, pollen fertility QTLs exhibited additive inheritance, with lowest fertility associated with the paternal allele, a pattern of inheritance suggestive of cytonuclear incompatibilities. The results imply that multiple genetic mechanisms underlie the rapid evolution of reproductive barriers in Draba.     

Duplication and adaptive evolution of the COR15 genes within the highly cold-tolerant Draba lineage (Brassicaceae)

Plants have evolved diverse adaptive mechanisms that enable them to tolerate abiotic stresses, to varying degrees, and such stresses may have strongly influenced evolutionary changes at levels ranging from molecular to morphological. Previous studies on these phenomena have focused on the adaptive evolution of stress-related orthologous genes in specific lineages. However, heterogenetic evolution of the paralogous genes following duplication has only been examined in a very limited number of stress-response gene families. The COR15 gene encodes a low molecular weight protein that plays an important role in protecting plants from cold stresses. Although two different copies of this gene have been found in the model species, Arabidopsis thaliana, evolutionary patterns of this small gene family in plants have not been previously explored. In this study, we cloned COR15-like sequences and performed evolutionary analyses of these sequences (including those previously reported) in the highly cold-tolerant Draba lineage and related lineages of Brassicaceae. Our phylogenetic analyses indicate that all COR15-like sequences clustered into four clades that corresponded well to the morphological lineages. Gene conversions were found to have probably occurred before/during the divergence of Brassica and Draba lineage. However, repeated, independent duplications of this gene have occurred in different lineages of Brassicaceae. Further comparisons of all sequences suggest that there have been significant inter-lineage differences in evolutionary rates between the duplicated and original genes. We assessed the likelihood that the differences between two well-supported gene subfamilies that appear to have originated from a single duplication, COR15a and COR15b, within the Draba lineage have been driven by adaptive evolution. Comparisons of their non-synonymous/synonymous substitution ratios and rates of predicted amino acid changes indicate that these two gene groups are evolving under different selective pressures and may be functionally divergent. This functional divergence was confirmed by comparing site-specific shifts in evolution indexes of the two groups of predicted proteins. The evidence of differential selection and possible functional divergence suggests that the duplication may be of adaptive significance, with possible implications for the explosive diversification of the Draba lineage during the cooling Quaternary stages and the following worldwide colonization of arid alpine and artic regions.     

On the Validity of the Genus Cochlidiosperma Reichenb. (Scrophulariaceae) as Supported by Additional Palynological Evidence

The pollen grains of Cochlidiosperma (Veronica) hederifolia and C. (Veronica) cymbalaria were examined under SEM and TEM. They differ vastly from those of all the others in Veronica (sensu Elenevskij, 1977, 1978). The taxonomic relationship between the group and the other Veronica spp. is discussed with respect to both gross morphology and pollen characters. Justification for the restoration of the genus as a valid taxon is argued and, finally, a number of new combinations are proposed. The group under consideration was sometimes treated as a separate genus but more often given different ranks in the genus Veronica, which has been a controversial group as to its concept and subdivision. No detail discussion has been made before on the relationship between the group and Veronica. Main purpose of the present mork is to examine pollen morphology and gross morphology of the group and to discussits relationship with Veronica.     

Extensive intraspecific chloroplast DNA (cpDNA) variation in the alpine Draba aizoides L. (Brassicaceae): haplotype relationships and population structure

Chloroplast DNA (cpDNA) sequence variation is currently the most widely used tool for the inference of phylogenetic relationships among plants at all taxonomic levels. Generally, noncoding regions tend to evolve faster than coding sequences and have recently been applied to the study of phylogenetic relationships among closely related taxa. An implicit assumption of many of these studies is that intraspecific cpDNA variation is either absent or low and therefore will not interfere with the reconstruction of interspecific relationships. A survey of cpDNA sequence variation in the common alpine plant species Draba aizoides L. was undertaken to assess levels of intraspecific cpDNA sequence variation. These levels were compared to levels of interspecific sequence divergence between D. aizoides and related alpine Draba species. Intraspecific cpDNA sequence divergence was extensive in D. aizoides, and intraspecific differences were often larger than interspecific differences. cpDNA haplotype relationships were explored using a maximum parsimony approach and minimum-spanning networks. Results from both methods were largely congruent but comparisons provided interesting insights into the presumed evolutionary history of cpDNA haplotypes. A combined effect of cpDNA introgression and complex lineage sorting was inferred to explain the pattern of cpDNA variation found in D. aizoides. Our results suggest that intraspecific cpDNA variation can be extensive and that intraspecific variation needs to be taken into account when inferring phylogenetic relationships among closely related taxa.     

Development and reproduction of Myzus persicae and Aphis fabae (Hom., Aphididae) on selected weed species surrounding sugar beet fields

Abstract:   Myzus persicae (Sulzer) and Aphis fabae (Scop.) are two major aphid species colonizing sugar beet. They have a very wide host range adapting to a large number of plant families and species. A series of cage experiments, conducted under 'winter' and 'summer' growth chamber conditions, showed that both species have the potential to use winter and summer weeds that are usually present in the vicinity of and within sugar beet fields as secondary hosts. Among all the weeds tested, Veronica hederifolia L. and Solanum nigrum L. were the most suitable for M. persicae . Although Brassica kaber (DC.) Wheeler was the weed species associated to the highest reproduction rate of this aphid, V. hederifolia showed a higher intrinsic rate of population increase due to the shorter prereproductive period of the aphid. Amsynckia intermedia Fish. and Mey and Amaranthus retroflexus L. were the most suitable weed hosts for A. fabae .     

狭果葶苈高温响应表达序列标签的分离与初步分析

目的:分离与分析白马雪山流石滩地区植物狭果葶苈高温响应基因,研究高山植物高温耐受机制。方法:应用磁珠介导的抑制消减杂交分离差异表达序列标签(EST),通过测序与Blastx比对,用Blast2go程序进行功能注释和代谢路径分析。结果:大部分EST功能与物质能量代谢、生物合成、蛋白和脂肪结合、转移酶活性相关,还有一些胁迫响应的基因。结论:狭果葶苈高温胁迫应答机制是非常复杂的,需要众多基因的参与。     

Draba skrivanekii,eine interessante Art aus Montenegro (Jugoslawien)

In den Herbarien der botanischen Abteilung des Nationalmuseums in Pr?honice (PR) werden zwei Belege aufbewahrt, die vonRohlena alsDraba athoa Boiss. bezeichnet sind. Später ordneteRohlena selbst diese Pflanzen der ArtD. elongata Host mit Bezeichnung var.skrivanekii Rohl. zu. Durch eine Analyse des Herbarmaterials hat sich erwiesen, dass es sich um eine selbständige Art—Draba skrivanekii (Rohl.)Chrtek—handelt, die in den Gebirgslagen Montenegros (Kom Vasojevi?ki) wahrscheinlich endemisch ist. Die nächstverwandte Art istDraba athoa (Griseb.)Boiss.     

Pollen and seed morphology of Nordic Draba (Brassicaceae): phylogenetic and ecological implications

Pollen and seed morphology were examined in 54 diploid and allopolyploid populations representing 15 Nordic species of the taxonomically complex genus Draba. The pollen size was strongly correlated with chromosome number, but it was unreliable for inferring the exact ploidal level of individual populations. Five main pollen types were recognized based on sculpturing of the exine. Two populations of D. lactea had conspicuously different exine sculpturing, supporting a previous hypothesis based on molecular data that this hexaploid is polyphyletic and has been derived from various combinations of diploid species. The pollen morphological data are also consistent with the hypotheses that the 16-ploid D. corymbosa is an intersectional allopolyploid derived from the sections Draba and Chrysodraba , that the hexaploid D. cinerea is a progenitor of the decaploid D. arctica , and that D. crassifolia and D. adamsii represent isolated allopolyploid lineages. The seed size and weight were only weakly correlated with chromosome number, but showed a close relationship to habitat ecology. The largest seeds were observed in species typical of closed habitats, in which seedling establishment probably is limited by competition with mosses. The seed coat surface had a characteristic verrucate reticulum, but the differentiation among species was vague or absent. The seed size and colour, however, distinguish some species, e.g., in the D. alpina complex, which otherwise are morphologically very similar.     

葶苈愈伤组织诱导及分化研究

为保护野生资源、实现人工栽培,本研究以葶苈(Draba nemorosa)嫩茎为材料,采用组织培养方法进行愈伤组织诱导与分化、不定芽生根与试管苗生根继代增殖培养,以及移栽和定植研究。结果表明,MS+6-BA 0.4 mg/L+2,4-D 2.5 mg/L是愈伤组织诱导培养和继代增殖培养的理想培养基;MS+6-BA 0.6 mg/L+NAA 0.1 mg/L 是愈伤组织分化培养和不定芽继代增殖培养的理想培养基;1/3MS+IAA 0.6 mg/L是不定芽生根培养和生根继代增殖培养的理想培养基;试管苗移栽成活率为86.8%,定植成活率为96.4%;定植苗保持了野生葶苈的植物学性状。     

Disulfide-stabilized helical hairpin structure and activity of a novel antifungal peptide EcAMP1 from seeds of barnyard grass (Echinochloa crus-galli)

This study presents purification, activity characterization, and (1)H NMR study of the novel antifungal peptide EcAMP1 from kernels of barnyard grass Echinochloa crus-galli. The peptide adopts a disulfide-stabilized α-helical hairpin structure in aqueous solution and thus represents a novel fold among naturally occurring antimicrobial peptides. Micromolar concentrations of EcAMP1 were shown to inhibit growth of several fungal phytopathogens. Confocal microscopy revealed intensive EcAMP1 binding to the surface of fungal conidia followed by internalization and accumulation in the cytoplasm without disturbance of membrane integrity. Close spatial structure similarity between EcAMP1, the trypsin inhibitor VhTI from seeds of Veronica hederifolia, and some scorpion and cone snail toxins suggests natural elaboration of different functions on a common fold.     

Multiple origins of the octoploid Scandinavian endemic Draba cacu minum: electrophoretic and morphological evidence

The octoploid Draba cacuminum (Brassicaceae) is one of the few endemic species in Scandinavia and has frequently been considered an example supporting the glacial survival theory. Two subspecies, ssp. cacuminum in southern Norway and ssp. angusticarpa in northern Scandinavia, have been described and suggested to be geographically diverged remnants of a more continuously distributed ancestor. To test an alternative hypothesis of independent origins of similar octoploids in different areas, we investigated populations of D. cacuminum and its possible progenitors using enzyme electrophoresis and morphological analysis. Electrophoretic analysis of progeny of D. cacuminum revealed high levels of fixed heterozygosity, suggesting that the species is a genetic alloploid. Fixed electrophoretic differences among the populations and additivity of electrophoretic phenotypes indicate that the octoploid D. cacuminum has originated at least three times by alloploidizations involving different populations of the hexaploid D. norvegica and a diploid species, possibly D. fladnizensis. Electrophoretic and morphometric data suggest that populations of D. cacuminum with broad siliculae have originated from populations of D. norvegica that had broad siliculae, and that populations of D. cacuminum with narrow siliculae have originated from populations of D. norvegica that had narrow siliculae. However, the electrophoretic and morphometric variation within D. cacuminum did not correspond to the geographic origin of the populations, and the previously described subspecies could not be recognized. Draba cacuminum gives no relevant information on the glacial survival theory; the polyploidizations may have occurred in postglacial time as well as in pre-Weichselian periods.     

辣根属和豆瓣菜属(十字花科)系统位置的分子证据

对十字花科葶苈族的辣根属、南芥族的豆瓣菜属及相关属种植物的叶绿体DNA的trnL内含子和trnL-F基因间隔区序列进行了测定分析。结果表明,辣根属植物与南芥族的山芥属、蔊菜属、豆瓣菜属、碎米荠属在系统发育树中聚成一支,与葶苈族的模式属葶苈属植物相隔较远,结合形态特征,本研究认为辣根属应从葶苈族移出,其系统位置应靠近山芥属、蔊菜属、豆瓣菜属、碎米荠属植物;此外,系统发育树中,豆瓣菜属植物并入碎米荠属中,表明二者具有更近的亲缘关系,本研究结果不支持《中国植物志》第33卷对辣根属和豆瓣菜属的系统位置的处理。     

Ploidal levels in the arctic-alpine polyploid Draba lactea (Brassicaceae) and its low-ploid relatives

Ploidal level information is of particular importance in intricate polyploid complexes such as in arctic-alpine Draba . Relative DNA content is reported for the tetra- and hexaploid D. lactea and seven of its low-ploid relatives. Flow cytometry was used to study 200 plants from 93 populations, the screening based on relative fluorescence. Absolute DNA content was determined by Feulgen densitometry for 13 plants from seven species, and reference chromosome numbers were determined in 12 plants (1–3 per species) representing six species. The plants grouped into diploids (2 n  = 16), tetraploids (2 n  = 32), hexaploids (2 n  = 48), and two triploids. Each ploidal level showed a linear increase in relative DNA content, pointing to a relatively recent polyploid origin. The diploid level was confirmed in D. nivalis, D. subcapitata, D. fladnizensis , and D. lonchocarpa. Draba palanderiana , reported previously as di-, tetra- and octoploid, was diploid in all investigated accessions. Hexa- and tetraploids were observed in D. lactea , in approximately the same ratio (8 : 1) as reported previously. The ploidal levels of the Central Asian D. altaica and D. turczaninovii are reported here for the first time as diploid and tetraploid, respectively.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 147 , 333–347.     

Draba streptobrachia (Brassicaceae), a new species from Colorado

Draba streptobrachia Price is an alpine species endemic to Colorado, U.S.A. It was treated byHitchcock (1941) asDraba spectabilis var.dasycarpa (Schulz) C. L. Hitchc., but is distinct fromD. spectabilis Greene in morphology, habitat, and chromosome number (g = ca 32 inD. streptobrachia, versusg = 10 and 16 inD. spectabilis) and therefore has been raised to the rank of species. Pollen fertility inD. streptobrachia is at or near zero and anthers consistently fail to dehisce, but fertile seeds are still produced, suggesting that the taxon reproduces by agamospermy.     

Ipangulines and minalobines, chemotaxonomic markers of the infrageneric Ipomoea taxon subgenus Quamoclit, section Mina

A comprehensive GC-MS analysis of 8 Ipomoea species belonging to the subgenus Quamoclit, section Mina revealed that the members of this taxon form combinations of two necine bases with rare necic acids resulting in unique pyrrolizidine alkaloids. The occurrence and diversity of these metabolites show remarkable variations: Some species, especially Ipomoea hederifolia and Ipomoea lobata, are able to synthesize a large number of alkaloids whereas others, especially Ipomoea coccinea and Ipomoea quamoclit, are poor synthesizers with only a few compounds. However, these metabolites are apparently chemotaxonomic markers of this infrageneric taxon in general. They represent either esters of (-)-platynecine (altogether 48 ipangulines and 4 further esters including results of a previous study) or esters of (-)-trachelanthamidine, an additional novel structural type called minalobines (altogether 21 alkaloids). Both types are characterized by section-specific rare necic acids, e.g., ipangulinic/isoipangulinic acid, phenylacetic acid. The alkaloids of Ipomoea cholulensis, I. coccinea, I. hederifolia, Ipomoea neei, and Ipomoea quamoclit were mono and diesters of platynecine. Minalobines turned out to be metabolites of I. lobata (Cerv.) Thell. (syn.: Mina lobata Cerv.) lacking ipangulines. The major alkaloid of this species, minalobine R, has been isolated and identified as 9-O-(threo-2-hydroxy-2-methyl-3-phenylacetoxy-butyryl)-(-)-trachelanthamidine on the basis of spectral data. Apparently only two of the species included in this study, Ipomoea cristulata and Ipomoea sloteri, are able to synthesize both, ipangulines as well as minalobines. Minalobine O could be isolated as a major alkaloid of I. cristulata, its structure has been established as 9-O-(erythro-2-hydroxy-2-methyl-3-tigloyloxy-butyryl)-(-)-trachelanthamidine on the basis of spectral data.