Claytonia Perfoliata Research Articles

Weeds Associated with Papaya Plants (Carica Papaya L.) in Bengkulu

Papaya crops associated with weeds are commonly found in Kepahiang and Rejang Lebong district, Bengkulu. The presence of weeds can affect the development and productivity of papaya. Until now, the species and diversity of weeds associated with papaya crops have not been reported. This study aimed to identify and determine weed density around papaya crops. Sampling was conducted to measure and calculate weed density using the quadratic method measuring 1 m x 1 m. The data collection was done by randomly taking the weeds on the plots at as many as 10 points. Based on the result of weed identification, there were 16 species of weeds spread over 9 families. The calculation of the highest relative density in Padang Lekat, Durian Depun Village, and Dua Jalur Road was Ageratum conyzoides (0,584%), Claytonia perfoliata (0,306%), and Eleusine indica (0,274%).

Bioluminescence Production by Turnip Yellows Virus Infectious Clones: A New Way to Monitor Plant Virus Infection.

We used the NanoLuc luciferase bioluminescent reporter system to detect turnip yellows virus (TuYV) in infected plants. For this, TuYV was genetically tagged by replacing the C-terminal part of the RT protein with full-length NanoLuc (TuYV-NL) or with the N-terminal domain of split NanoLuc (TuYV-N65-NL). Wild-type and recombinant viruses were agro-infiltrated in Nicotiana benthamiana, Montia perfoliata, and Arabidopsis thaliana. ELISA confirmed systemic infection and similar accumulation of the recombinant viruses in N. benthamiana and M. perfoliata but reduced systemic infection and lower accumulation in A. thaliana. RT-PCR analysis indicated that the recombinant sequences were stable in N. benthamiana and M. perfoliata but not in A. thaliana. Bioluminescence imaging detected TuYV-NL in inoculated and systemically infected leaves. For the detection of split NanoLuc, we constructed transgenic N. benthamiana plants expressing the C-terminal domain of split NanoLuc. Bioluminescence imaging of these plants after agro-infiltration with TuYV-N65-NL allowed the detection of the virus in systemically infected leaves. Taken together, our results show that NanoLuc luciferase can be used to monitor infection with TuYV.

Idiosyncratic shifts in life‐history traits at species' geographic range edges

Anthropogenic changes drive shifts in species' geographic distributions and increase the occurrence of leading or trailing‐edge marginal populations. Theoretical predictions and empirical observations indicate substantial changes in life‐history traits in marginal populations, often involving dispersal and reproductive abilities. Using a common garden experiment, we studied the variation of life‐history traits of populations sampled on spatial gradients extending from range‐core to range‐edge habitats for three expanding (miner's lettuceClaytonia perfoliata, Danish scurvygrassCochlearia danicaand rock samphireCrithmum maritimum) and one receding plant species (dune pansyViola tricolorsubs.curtisii). We monitored life‐history traits related to dispersal, phenology, survival, reproductive output and selfing ability. Significant shifts in life‐history traits between central and marginal populations strongly differed among species. Marginal populations of the three expanding species displayed modified seed weight in natura, suggesting increased dispersal abilities in leading‐edge populations. Discarding unassessed maternal effects, this trait modification can be due to phenotypic plasticity or to genetic differentiation. In miner's lettuce, marginal expanding populations show advanced phenology and higher reproductive output, that may potentially influence their colonization ability. In rock samphire, life‐history traits showed large intra‐ and inter‐population variability that did not follow a core‐to‐edge geographic trend, except for seed size. Finally, the receding populations of the dune pansy displayed a shift towards a plant architecture maximizing survival but reducing individual reproductive success. Altogether, our results indicated a common trend for increased dispersal abilities in marginal populations of expanding species. However, shifts in species' distributions may drive idiosyncratic changes in other life‐history traits, for which we observed no general evolutionary syndrome at range edges. These findings go along a stochastic view of trait evolution during range expansion, and question how to draw predictive projections of species' distribution shifts under current global change.

Post-acquisition effects of viruses on vector behavior are important components of manipulation strategies

A growing number of studies suggest that plant viruses manipulate host plant phenotypes to increase transmission-conducive behaviors by vectors. Studies on this phenomenon frequently omit examination of interactions that occur after vectors acquire virions, which provides an incomplete understanding of the ecology of plant virus manipulation. Here, by taking a full factorial approach that considered both the infection status of the host (Montia perfoliata) and viruliferous status of the aphid (Myzus persicae), we explored the effects of a circulative, non-propagative virus (Turnip yellows virus [TuYV]) on a suite of behavior and performance metrics that are relevant for virus transmission. Our results demonstrate that viruliferous aphids exhibited an increased velocity of movement and increased activity levels in locomotor and dispersal-retention assays. They also had increased fecundity and showed a capacity to more efficiently exploit resources by taking less time to reach the phloem and ingesting more sap, regardless of plant infection status. In contrast, non-viruliferous aphids only exhibited enhanced fecundity and biomass on TuYV-infected hosts, and had overall reduced dispersal and locomotor activity relative to viruliferous aphids. In this pathosystem, post-acquisition effects were stronger and more conducive to virus transmission than the purely pre-acquisition effects mediated by virus effects on the host plant. Our study provides additional support for the hypothesis that virus manipulation of vector behavior includes both pre- and post-acquisition effects and demonstrates the importance of considering both components when studying putative virus manipulation strategies.

Alien herbaceous plant species new to Lithuania

AbstractThis paper presents information about ten new alien plant species recorded in Lithuania in the period from 1995 to 2014. These species belong to eight families: Cucurbitaceae (Lagenaria siceraria), Juncaceae (Luzula sylvestris), Lamiaceae (Physostegia virginiana, Sideritis montana), Poaceae (Melica altissima, Miscanthus sacchariflorus), Portulacaceae (Claytonia perfoliata), Scrophulariaceae (Digitalis purpurea), Solanaceae (Datura inoxia) and Zygophyllaceae (Tribulus terestris). Three species (Claytonia perfoliata, Sideritis montana and Tribulus terestris) were introduced accidentally, whereas other seven species were introduced deliberately and later escaped from cultivation. One species, Luzula sylvatica, is ascribed to the group of established aliens, whereas other recorded species are treated as casual. Local establishment of Claytonia perfoliata, Digitalis purpurea and Melica altissima is expected, whereas Miscanthus sacchariflorus can become established and even invasive in the future.

An experimental test of local adaptation among cytotypes within a polyploid complex.

The geographic distributions of polyploids suggest they can have distinct and sometimes broader niches compared to diploids. However, relatively few field experiments have investigated whether range differences are associated with local adaptation or reflect other processes, such as dispersal limitation. In three years of transplants across the elevational ranges of five cytotypes in the Claytonia perfoliata complex, we found evidence for local adaptation. In at least one study year germination was higher within the natural range for each cytotype, and four of the five cytotypes attained larger biomass within their natural range. Fitness within and beyond range varied across years, with two instances of cytotypes showing higher fitness beyond the range, highlighting a potential role of temporal variability in cytotype differentiation. Polyploids as a group did not outperform diploids, but the cytotype with highest fitness across environments was a hexaploid reported to be invasive. Our results suggest that differences in geographic ranges within the C. perfoliata complex reflect local adaptation of cytotypes. Although we did not find a general polyploid advantage, our findings support the idea that occasional polyploid cytotypes exhibit high fitness relative to other cytotypes, and contribute to growing evidence supporting ecological differentiation of cytotypes within polyploid complexes.

Oxalate Content of Miner’s Lettuce Irrigated with Water or Fertilizer Solutions

The total, soluble and insoluble oxalate contents of the small, large and cauline leaves and small and large stems of miner’s lettuce (Claytonia perfoliata ) plants which had been irrigated with tap water or a soluble fertilizer were extracted and measured using HPLC chromatography. Overall, all plant parts of miner’s lettuce analyzed contained high levels of total and soluble oxalates; however plants irrigated with fertilizer contained lower levels of oxalates compared with plants irrigated with water. On a dry matter basis, the small leaves contained higher levels of total oxalate when compared to the total oxalate in the large leaves. Soluble oxalate in the leaves of plants irrigated with water ranged from 2.6 to 7.5 mg/100g dry matter (DM) and was significantly higher (P < 0.05) than the leaves of the fertilizer-watered plants, which ranged from 1.8 to 2.8 mg/100g DM. The soluble oxalate in the small and large stems of the fertilizer-watered plants ranged from 1.20 to 1.5 mg/100g DM and was significantly lower (P < 0.05) than the water-treated small and large stems, which ranged from 3.75 to 4.4 mg/100g DM. It is recommended that the leaves of miner’s lettuce should be consumed in moderation.

Phenotypic and transgenerational plasticity promote local adaptation to sun and shade environments

Adaptive plasticity is expected to be important when the grain of environmental variation is encompassed in offspring dispersal distance. We investigated patterns of local adaptation, selection and plasticity in an association of plant morphology with fine-scale habitat shifts from oak canopy understory to adjacent grassland habitat in Claytonia perfoliata. Populations from beneath the canopy of oak trees were >90 % broad leaved and large seeded, while plants from adjacent grassland habitat were >90 % linear-leaved and small seeded. In a 2-year study, we used reciprocal transplants and phenotypic selection analysis to investigate local adaptation, selection, plasticity and maternal effects in this trait-environment association. Transgenerational effects were studied by planting offspring of inbred maternal families grown in both environments across the same environments in the second year. Reciprocal transplants revealed local adaptation to habitat type: broad-leaved forms had higher fitness in oak understory and linear-leaved plants had higher fitness in open grassland habitat. Phenotypic selection analyses indicated selection for narrower leaves and lower SLA in open habitat, and selection for broad leaves and intermediate values of SLA in understory. Both plant morphs exhibited plastic responses in traits in the same direction as selection on traits (narrower leaves and lower SLA in open habitat) suggesting that plasticity is adaptive. We detected an adaptive transgenerational effect in which maternal environment influenced offspring fitness; offspring of grassland-reared plants had higher fitness than understory-reared plants when grown in grassland. We did not detect costs of plasticity, but did find a positive association between leaf shape plasticity and fitness in linear-leaved plants in grassland habitat. Together, these findings indicate that fixed differences in trait values corresponding to selection across habitat contribute to local adaptation, but that plasticity and maternal environmental effects may be favored through promotion of survival across heterogeneous environments.

Cytogeography and genome size variation in the Claytonia perfoliata (Portulacaceae) polyploid complex.

Genome duplication is a central process in plant evolution and contributes to patterns of variation in genome size within and among lineages. Studies that combine cytogeography with genome size measurements contribute to our basic knowledge of cytotype distributions and their associations with variation in genome size. Ploidy and genome size were assessed with direct chromosome counts and flow cytometry for 78 populations within the Claytonia perfoliata complex, comprised of three diploid taxa with numerous polyploids that range to the decaploid level. The relationship between genome size and temperature and precipitation was investigated within and across cytotypes to test for associations between environmental factors and nuclear DNA content. A euploid series (n = 6) of diploids to octoploids was documented through chromosome counts, and decaploids were suggested by flow cytometry. Increased variation in genome size among populations was found at higher ploidy levels, potentially associated with differential contributions of diploid parental genomes, variation in rates of genomic loss or gain, or undetected hybridization. Several accessions were detected with atypical genome sizes, including a diploid population of C. parviflora ssp. grandiflora with an 18 % smaller genome than typical, and hexaploids of C. perfoliata and C. parviflora with genomes 30 % larger than typical. There was a slight but significant association of larger genome sizes with colder winter temperature across the C. perfoliata complex as a whole, and a strong association between lower winter temperatures and large genome size for tetraploid C. parviflora. The C. perfoliata complex is characterized by polyploids ranging from tetraploid to decaploid, with large magnitude variation in genome size at higher ploidy levels, associated in part with environmental variation in temperature.

Polyploidy associated with altered and broader ecological niches in the Claytonia perfoliata (Portulacaceae) species complex

Polyploids are often hypothesized to have distinct and broader niches than their diploid progenitors. Differences in geographic distributions between diploid and polyploids are frequently used to infer niche differentiation and increased breadth, but they are seldom used to test these hypotheses explicitly. Niche overlap and breadth were compared for diploids, tetraploids, and hexaploids of three taxa in the Claytonia perfoliata complex (C. parviflora, C. perfoliata, and C. rubra) with the use of species distribution models. Resampling and randomization approaches were used to test hypotheses of niche differentiation, breadth, and conservatism. Niche differentiation was detected between polyploid and diploid cytotypes assigned to the same taxon (e.g., C. parviflora 2× vs. 4×) but not between hexaploids and tetraploids within a taxon (e.g., C. parviflora 4× vs. 6×). Individual hexaploid cytotypes had broader ecological niches than individual diploid cytotypes. However, as a group the three hexaploid taxa did not exceed the combined niche breadth of the three diploids, suggesting that polyploidy does not result in transgressive niche breadth for this group. Niche overlap was lowest among diploids and was highest among the three hexaploid cytotypes, consistent with introgression associated with polyploidy resulting in greater ecological similarity. Although cytotypes possessed nonidentical niches, after accounting for environmental differences among ranges, cytotypes were more similar than expected, suggesting niche conservatism and similar responses to environmental characteristics. These results suggest that polyploids occupy distinct and broader niches relative to diploids but that cytotypes also share fundamentally similar responses to environmental variation across ploidy levels.

Shrubs as ecosystem engineers in a coastal dune: influences on plant populations, communities and ecosystems

Question: How do two shrubs with contrasting lifehistory characteristics influence abundance of dominant plant taxa, species richness and aboveground biomass of grasses and forbs, litter accumulation, nitrogen pools and mineralization rates? How are these shrubs ‐ and thus their effects on populations, communities and ecosystems ‐ distributed spatially across the landscape? Location: Coastal hind-dune system, Bodega Head, northern California. Methods: In each of 4 years, we compared vegetation, leaf litter and soil nitrogen under canopies of two native shrubs ‐ Ericameria ericoides and the nitrogen-fixing Lupinus chamissonis ‐ with those in adjacent open dunes. Results: At the population level, density and cover of the native forb Claytonia perfoliata and the exotic grass Bromus diandrus were higher under shrubs than in shrub-free areas, whereas they were lower under shrubs for the exotic grass Vulpia bromoides. In contrast, cover of three native moss species was highest under Ericameria and equally low under Lupinus and shrub-free areas. At community level, species richness and aboveground biomass of herbaceous dicots was lower beneath shrubs, whereas no pattern emerged for grasses. At ecosystem level, areas beneath shrubs accumulated more leaf litter and had larger pools of soil ammonium and nitrate. Rates of nitrate mineralization were higher under Lupinus, followed by Ericameria and then open dune. At landscape level, the two shrubs ‐ and their distinctive vegetation and soils ‐ frequently had uniform spatial distributions, and the distance separating neighbouring shrubs increased as their combined sizes increased. Conclusions: Collectively, these data suggest that both shrubs serve as ecosystem engineers in this coastal dune, having influences at multiple levels of biological organization. Our data also suggest that intraspecific competition influenced the spatial distributions of these shrubs and thus altered the distributionoftheir effects throughout the landscape.

First Report of Cucumber mosaic virus and Turnip vein-clearing virus in Dichondra repens in France, Italy, and China.

During surveys of Dichondra repens (kidneyweed, family Convolvulaceae) turfs in public gardens of the Franco-Italian Riviera from 1993 to 2003, leaf mosaic and yellow ringspot symptoms have been observed in Antibes, Menton, Nice, and Vallauris (France) and San Remo and La Mortola (Italy). Isolates from these six locations and from two locations in China (Shanghai and Kunming) have revealed the presence of Cucumber mosaic virus (CMV) based on the behavior of a range of manually inoculated plants (1), the observation of 30 nm isometric particles in semipurified extracts of inoculated Nicotiana tabacum 'Xanthi' plants with the electron microscope, and positive reactions in double antibody sandwich (DAS)-ELISAs with specific polyclonal antibodies. All isolates were shown to belong to group II of CMV isolates (3) by double-immunodiffusion analysis. CMV was previously identified in D. repens in California in 1972 (4). Following isolation from local lesions on Vigna unguiculata and multiplication in 'Xanthi' tobacco plants, two of the isolates were used to inoculate seedlings of D. repens manually or by Aphis gossypii aphids. Two months later, all inoculated plants showed symptoms similar to those previously observed and were positive in DAS-ELISA. In 2000, a D. repens sample collected in Antibes showing similar symptoms as above, induced necrotic local lesions in inoculated 'Xanthi' plants in 48 h, followed by systemic mosaic symptoms typical of CMV, therefore revealing the presence of a second virus. That virus was separated from CMV in apical, noninoculated leaves of Chenopodium quinoa and then used to inoculate a range of test plants. It was infectious in most plants of the families Solanaceae (including Cyphomandra betacea) and Brassicaceae, together with in Chenopodium amaranticolor, C. quinoa, Claytonia perfoliata, Convolvulus spp. 'Belle de jour', Digitalis purpurea, Gomphrena globosa, Ocimum basilicum, Plantago lanceolata, and Valerianella olitoria. It induced asymptomatic systemic infections in D. repens. Numerous, rod-shaped, 300 nm long particles were observed in sap extracts of infected plants with the electron microscope, suggesting the presence of a tobamovirus. A set of primers polyvalent for tobamoviruses (2) allowed the amplification of a DNA product of approximately 800 bp through reverse transcription-PCR performed with total RNA extracts from inoculated 'Xanthi' plants. The DNA product was cloned and sequenced (GenBank Accession No. EU927306) revealing that the virus belonged to a tobamovirus lineage including Ribgrass mosaic virus and viruses infecting cruciferous plants (Turnip vein-clearing virus [TVCV] and Youcai mosaic virus) and was closest to TVCV (95% amino acid identity; GenBank Accession No. NC_001873). To our knowledge, this is the first report of TVCV in D. repens.

First Report of Passiflora chlorosis virus in Bituminaria bituminosa in Europe.

Bituminaria bituminosa (L.) Stirton (pitch trefoil) is a perennial legume endemic to the Mediterranean Basin used as forage in arid areas and for stabilization of degraded soils. Mosaic and chlorotic ringspot symptoms have been observed in leaves of B. bituminosa in the Provence-Alpes-Côte d'Azur and Rhône-Alpes regions (France), Liguria (Italy), and Spain since 1975. In crude leaf extracts from more than 50 samples of diverse geographical origins, flexuous particles 680 to 720 nm long and 12 nm wide and pinwheel-like inclusions have been observed with the electron microscope, suggesting infection with a member of the family Potyviridae. The presence of a virus was confirmed by the use of potyvirus-polyvalent ELISA reagents (Potyvirus group test; Agdia, Elkhart, IN) and by the amplification of a DNA fragment of the expected size (≈1,650 bp) with extracts of isolates from different locations using reverse transcription (RT)-PCR with primers specific to members of the Potyviridae (3) corresponding to the 3' end of the virus genome. The amplified fragment of an isolate from Coaraze (Alpes Maritimes Department, France) was cloned and two cDNA clones corresponding to this amplicon were sequenced (GenBank Accession Nos. EU334546 and EU334547). These two sequences facilitated development of new primers (5'-AAARGCRCCCTATATAGCAG-3' and 5'-TATAAAGGTAACGCTAGGTGG-3') to specifically amplify and sequence the coat protein (CP)-coding region of isolates of the virus from five additional French locations. The amino acid sequences of the CP amplicon were more than 96% identical among the French isolates. Comparison with other virus sequences with the BLASTn program revealed that these isolates belonged to the same species as the potyvirus Passiflora chlorosis virus (2), with 89 to 90% and 95 to 97% identity at the nucleotide and amino acid levels, respectively, for the CP-coding region (1). The host range of the virus was evaluated by manual inoculation with the Coaraze isolate and was found to be very narrow. No symptoms and no infections were obtained in Capsella bursa-pastoris, Capsicum annuum, Claytonia perfoliata, Cucumis melo, Cucumis sativus, Cucurbita pepo, Datura stramonium, Gomphrena globosa, Medicago sativa, Nicotiana benthamiana, N. glutinosa, N. tabacum, Ocimum basilicum, Petunia hybrida, Phaseolus mungo, Physalis peruviana, Pisum sativum, Psoralea glandulosa, Ranunculus sardous, Salvia splendens, Solanum lycopersicum, Trifolium repens, Vicia faba, Vigna unguiculata, or Zinnia elegans. Necrotic local lesions were observed in Chenopodium amaranticolor, C. quinoa, and in all eight cultivars of Phaseolus vulgaris tested. The virus was transmitted either manually or by the green peach aphid (Myzus persicae) to healthy B. bituminosa seedlings. Symptoms appeared in 10 to 15 weeks, and the virus was detected in the symptomatic plants by RT-PCR. To our knowledge, this is the first report of a virus infecting B. bituminosa.

Beet poleroviruses: close friends or distant relatives?

SUMMARY Taxonomy: There are three members of the genus Polerovirus (family Luteoviridae) that induce yellowing of sugar beet: Beet mild yellowing virus (BMYV), Beet chlorosis virus (BChV) and Beet western yellows virus-USA (BWYV-USA, Fig. 1). Non-beet-infecting isolates of BWYV found particularly within Europe have now been re-named Turnip yellows virus (TuYV). Species-specific antibodies are unavailable, but the viruses can be distinguished by RT-PCR using primers specifically designed to the 5' end of their respective genomes. Physical properties: The isometric virus particles are approximately 26 nm in diameter and the genome consists of a single strand of positive sense RNA that utilizes almost all known plant virus gene expression strategies (initiation bypass, translational frameshifting and readthrough, synthesis of subgenomic RNA and proteolytic processing). Many members of the Chenopodiaceae are susceptible, including commercial crops of sugar beet (Beta vulgaris), red beet and spinach. Experimental hosts include Montia perfoliata, Nicotiana benthamiana and Arabidopsis thaliana. Sugar beet infected with beet poleroviruses show patches of chlorosis on the older leaves 4-6 weeks post-infection; these areas expand until the whole leaf becomes yellow and older leaves then tend to thicken and become brittle. Beet poleroviruses are transmitted in a persistent (circulative, non-propagative) manner by several different aphid species, Myzus persicae being the most important vector.

Beet yellows virus: the importance of being different

SUMMARY Taxonomic relationship: Type member of the genus Closterovirus, family Closteroviridae. A member of the alphavirus-like supergroup of positive-strand RNA viruses. Physical properties: Virions are flexuous filaments of approximately 1300 nm in length and approximately 12 nm in diameter that are made up of a approximately 15.5 kb RNA and five proteins. The major capsid protein forms virion body of helical symmetry that constitutes approximately 95% of the virion length. The short virion tail is assembled by the minor capsid protein, Hsp70-homologue, approximately 64-kDa protein, and approximately 20-kDa protein. Viral proteins: The 5'-most ORFs 1a and 1b encode leader proteinase and RNA replicase. The remaining ORFs 2-8 are expressed by subgenomic mRNAs that encode 6-kDa membrane protein, Hsp70 homologue, approximately 64-kDa protein, minor and major capsid proteins, approximately 20-kDa protein, and approximately 21-kDa protein, respectively. Hosts: The principal crop plants affected by Beet yellows virus (BYV) are sugar beet (Beta vulgaris) and spinach (Spinacea oleracea). In addition, BYV was reported to infect approximately 120 species in 15 families. Most suitable propagation species are Nicotiana benthamiana, Tetragonia expansa, and Claytonia perfoliata.

Nomenclatural Changes and New Taxa in Claytonia (Portulacaceae) in Western North America

Nomenclatural Changes and New Taxa in Claytonia (Portulacaceae) in Western North America

The use of monoclonal antibodies to detect beet mild yellowing virus and beet western yellows virus in aphids

SummaryInformation on infectivity of the aphids which invade sugar beet root crops each Spring is required for forecasting incidence and providing advice on control of virus yellows. Monoclonal antibodies, produced in the USA to barley yellow dwarf virus (BYDV) and in Canada to beet western yellows virus (BWYV), were used to distinguish between sugar‐beet‐infecting strains of the luteovirus beet mild yellowing virus (BMYV), and the non‐beet‐infecting strains of the closely‐related BWYV in plant and aphid tissue. Totals of 773 immigrant winged Myzuspersicae and 124 Macrosiphum euphorbiae were caught in water traps in a crop of sugar beet between 25 April and 5 August 1990. Using the monoclonal antibodies and an amplified ELISA, 67%M. persicae and 19%M. euphorbiae were shown to contain BWYV; 8%M. persicae and 7%M. euphorbiae contained BMYV. In studies with live winged aphids collected from the same sugar beet field during May, 25 of 60 M. persicae and two of 13 M. euphorbiae transmitted BWYV to the indicator host plant Montia perfoliata; two M. persicae and two M. euphorbiae transmitted BMYV. In another study three of 65 M. persicae and one of three M. euphorbiae in which only BWYV was detected, transmitted this virus to sugar beet.

Variation among British isolates of potato leafroll virus

SUMMARYTwenty isolates of potato leafroll virus (PLRV) were readily transmitted by Myzus persicae from a wide range of potato cultivars to Physalis floridana. The isolates also infected Montia perfoliata but not turnip or broad bean, and all were readily detected by direct enzyme‐linked immunosorbent assay. Four isolates, selected to represent the range of differences in severity of symptoms in P. floridana, also induced symptoms of differing severity in M. perfoliata, but their virulence in one species did not necessarily parallel that in the other. In general, virus concentration increased with increasing symptom severity. None of these four isolates was transmitted readily by Macrosiphum euphorbiae and their particles were antigenically indistinguishable in gel‐diffusion precipitin tests.Further tests on one PLRV‐infected potato plant from which virus was at first not transmitted by M. persicae showed that it contained a poorly‐transmissible isolate (isolate 15). The inefficient transmission of this isolate could not be attributed to inadequate uptake or retention by M. persicae of virus from P. floridana, and aphids failed to transmit isolate 15 when it was acquired from purified preparations in membrane‐feeding tests. Although the poor aphid transmissibility of isolate 15 is therefore an intrinsic property of its particles, these were antigenically indistinguishable from the particles of readily aphid‐transmissible isolates.Immunoelectron microscopy tests showed that PLRV and beet mild yellowing virus are antigenically closely related.

Flavonol Glycoside Variation in Diploids of the Claytonia perfoliata Complex (Portulacaceae)

Three allopatric, morphologically distinct diploid species and their auto- and allopolyploid derivatives constitute the Claytonia perfoliata complex. Diploid C. rubra synthesizes kaempferol-3-O-glucoside, kaempferol-3-O-arabinosylglucoside, and novel kaempferol-3-O-rhamnosylarabinosylglucoside. Claytonia perfoliata dip- loids yield the same array of glycosides but both kaempferol and quercetin are glycosylated. Unlike the autogamous C. rubra or C. perfoliata, the facultatively xe- nogamous diploid C. parvflora makes abundant diglycosides of kaempferol and quercetin including rhamnosylglucosides, arabinosylglucosides, and a glucosylglu- coside. In all three taxa flavonol-3-O-glycosides show little interpopulational varia- tion and are localized in floral tissue. Flavonoid data support a multi-species general- purpose classification for the C. perfoliata complex. Considerable descriptive information that unravels the morphological and cytological complexity of the myriad of forms attributable to the Claytonia perfoliata complex has been published (Miller 1976, 1978). Dip- loid populations of Claytonia parviflora Hook., C. rubra (T. Howell) Ti- destr., and C. perfoliata Willd. have been clearly distinguished on mor- phological grounds. Each diploid occupies a different, well-defined habitat. Diploid, annual C. perfoliata is autogamous and widely scattered in moist, naturally disturbed sites over a 3000 km geographic range from low elevations in the California Coast, Transverse, and Peninsular ranges, through mid-elevations in the Sonoran Desert mountains of southern Arizona, to high elevation coniferous forests of the Sierra Madre Occidental and Trans-Mexican Volcanic Belt. High polyploids of this species occur as a disjunct population in the Guatemalan Highlands. In contrast, diploids of C. parviflora are facultatively xenogamous annuals that occur sporadically within the foothill woodland belt of the California Sierra Nevada. A third diploid, C. rubra is obligately autogamous and grows in disturbed coniferous and sagebrush woodlands or along water- courses in the western Rocky Mountains, northern Great Basin, Cascade Range, Klamath Mountains, and Sierra Nevada. This species, at the dip- loid level, reaches a southern limit at high elevations on Mt. Pinos in the California Transverse Ranges. This paper presents evidence that each diploid taxon displays a distinct

Phenotypic Variation, Distribution and Relationships of Diploid and Tetraploid Populations of the Claytonia perfoliata Complex (Portulacaceae)

Chromosome counts from 235 populations of Claytonia (Montia) perfo- liata (sensu lato) reveal a polyploid pillar complex based on three morphologically different and geographically defined diploids. Claytonia perfoliata Willdenow with linear juvenile leaves and deltoid (mucronate) mature basal leaves ranges south- eastward from the Coast Ranges of California, through the Sonoran Desert Ranges of Arizona, to high elevation coniferous forests of Mexico and Guatemala. In con- trast, diploid C. rubra (Howell) Tidestrom generally occurs in drier montane and transmontane coniferous woodlands of the Sierra Nevada and Cascade Ranges. It has basal leaves that vary ontogenetically from rhombic to deltoid (obtuse). Diploid C. parv-flora Hooker is Sierra Nevadan and its juvenile and mature basal leaves are all linear. A fourth entity in this species complex, C. perfoliata ssp. viridis (Davidson) Fellows, contributes to variation at the tetraploid level but has not yet been found as a diploid. Progeny of field collected tetraploids resembling C. perfoliata and C. rubra diploids were grown under uniform regimes of light, temperature, and mois- ture for comparison with their diploid counterparts. Each family of progeny was indistinguishable from its parent, implying a high degree of self-fertilization in nat- ure. Comparisons of pollen-ovule ratios and observations of flower structure indicate that diploid C. parv flora is facultatively xenogamous while the other two diploid species are prevailingly autogamous. The distribution of tetraploids tends to parallel that of their diploid morphological counterparts. The often discontinuous variability found in natural populations of this species complex can be ascribed in part to sympatry of autogamous heteroploid biotypes. Environmentally induced variation is an additional complicating factor in the morphological analysis of mixed popu- lations. The developmental sequence of basal leaf shapes is genotypically deter- mined, but plants in unfavorable habitats may flower prematurely and thus differ from their siblings in the taxonomically important trait of leaf shape.