Ecological relations of agricultural populations of ecdysteroid-containing plants Rhaponticum carthamoides (Willd.) Iljin and Serratula coronata L. with herbivorous insects report 2. Composition variability of phytoecdysteroids in agrocenoses and their role in the vulnerability of plants to phytophagans

The accumulation and variability of ecdysteroids, which are analogs of the insect molting hormones, were studied during ontogeny of agricultural populations of Rhaponticum carthamoides (Leuzea carthamoides DC.) and Serratula coronata with relation to the plant age and cultivation conditions. The physiological role of ecdysteroids in the ecological interactions with pests was evaluated. It was found that the enhancement of herbivore activity coincided with biochemical changes in the composition of ecdysteroids having different physiological activities and was accompanied by damage to reproductive organs. During ontogenetic (age-related) changes and seasonal development in the vegetation season, the content of the physiologically active ecdysteroid 20-hydroxyecdysone decreased and relatively moderately active inokosterone and weakly active ecdysone were accumulated in reproductive shoots.     

Phytoecdysteroids from the juice of Serratula coronata L. (Asteraceae).

Seven phytoecdysteroids have been isolated from Serratula coronata L. One of them is a new phytoecdysteroid, 3-epi-20-hydroxyecdysone. Two further ecdysteroids, 20-hydroxyecdysone 22-acetate and taxisterone, are isolated from this species for the first time in addition to the typical S. coronata ecdysteroids, 20-hydroxyecdysone, ecdysone, ajugasterone C and polypodine B. The juice squeezed from aerial parts of fresh plants of S. coronata was extracted with ethyl acetate. The ecdysteroids were isolated by a combination of chromatographic techniques (mainly HPLC) and identified by 1D and 2D (1)H and (13)C NMR experiments and mass-spectrometry. The biological activities of 3-epi-20-hydroxyecdysone (EC(50)=1.6 x 10(-7) M), taxisterone (EC(50)=9.5 x 10(-8) M) and ajugasterone C (EC(50)=6.2 x 10(-8) M) have been determined in the Drosophila melanogaster B(II) bioassay for ecdysteroid agonist activity.     

Autecology of Acacia Senegal (L.) Willd.

Acacia senegal (L) Willd. is a small sized tree species of Tropical arid region of Southern West Pakistan. It is well-known for producing gum arabic. Fruits from dry streams with loamy sand soil type were of bigger size whereas seed output per pod and seed weight were higher in hilly regions. The seeds possess external dormancy (seed coat), which can be broken by mechanical and chemical scarification, water (cold and boiling) and dark treatments. Seeds gave high percentage of germination in fine sand in pot culture. Germination percentage was high in May–July. The growth rate of seedlings both in pot culture and field conditions was high in April, May, June and July. Seeds collected from different localities showed considerable variation in germination capacity. Percentage and rate of germination increased with the lapse of time. Correlation of growth and abundance ofAcacia senegal was found with topography, soil texture, soil structure, soil consistence, maximum water holding capacity, wilting coefficient (sub-surface soil), soil carbonates (surface soil) soil pH (surface soil) and community associates. The plant can be propagated by shoot cuttings. Smaller and thinner cuttings are easily propagated. The plant is infested by Buffaloe tree hopper and is also infected byCladosporium herbarum. Occasionally seedlings are attacked byFusarium sp. The relative turgidity of branches was found to be high throughout the study period, but the leaves showed considerable variation.     

A comparative analysis of the proteins from a cell culture and from field plants of the ecdysteroid producer Serratula coronata L.]

Differences in the composition and amount of proteins synthesized in the cell culture and leaves of field plants Serratula coronata have been shown. They proceed from differences in intensity of synthesis of secondary metabolites, ecdysteroids, whose content in the cell culture is considerably lower.     

In vitro propagation of the gum arabic tree (Acacia Senegal (L.) Willd.) 1. Developing a rapid method for producing plants

The method described herein permitted production of three to four micropropagules of Acacia Senegal from one uninodal explant. The explants were taken from plants produced either in a sterile environment or during four years in a greenhouse. Zeatin or 6-benzylaminopurine (BAP) were mixed, at different concentrations, with Murashige and Skoog's medium (MS) of which the amount of macroelements was divided in half (MS mod.). At a concentration of 5.0×10^–5 M, zeatin produced a better multiplication rate after 60 d for the two types of plant stock than did BAP. A two stage process was necessary to obtain a rooting rate of the small cuttings close to 100%. The first stage, called induction, consisted of leaving the cuttings for 6 to 12 d on a Jordan's medium (JN) of which the amount of macroelements was reduced by half (JN mod.) and in which NAA at a concentration of 5.0×10^–5 M was added. The second stage, called root extension, required that the small cuttings be planted on this second hormone-free medium. Roots appeared after a few days. Acclimatization in a greenhouse occured with a survival rate of close to 100% when the rooted in vitro plants were transplanted to pots containing a mixture of vermiculite and top soil (11; v/v).Abbreviations BAP 6-benzylaminopurine - NAA a-Naphthaleneacetic acid - JN Jordan et al. (1978) medium - MS Murashige and Skoog (1962) medium - mod modified     

Microcosm method to assess survival of recombinant bacteria associated with plants and herbivorous insects

A microcosm method was developed to investigate survial and fate of genetically engineered bacteria associated with plant surfaces and a plant-feeding insect, the variegated cutworm,Peridroma saucia. Larvae on radish plants in microcosms were sprayed with nonrecombinantPseudomonas cepacia and a recombinant strain ofP. cepacia carrying the transmissible plasmid R388::Tn1721. Leaf, whole insect, foregut, and frass samples were periodically assayed over a 48-h period to enumerate total bacteria andP. cepacia strains. Immediately after spraying,P. cepacia comprised about 20%–30% of the total population on leaves, which was 2×10⁷ cfu/g of leaf. Approximately 4×10⁷ total cfu were recovered from each gram of whole insect, when theP. cepacia strains averaged about 3×10⁵ cfu/g. After 2 days, the total epiphytic population had increased approximately fourfold, while theP. cepacia strains had decreased to 2%–30% of their initial numbers. After 24 and 48 h, eachP. cepacia strain numbered between 10⁴ and 10⁵ cfu/g of insect in foregut samples, whereas none was detectable in frass. Plasmid transfer fromP. cepacia R388::Tn1721 to the nonrecombinant recipientP. cepacia strain was not observed.     

Somatic hybridization between birdsfoot trefoil (Lotus corniculatus L.) and L. conimbricensis Willd

Summary Somatic hybrid plants were produced by fusion of birdsfoot trefoil (Lotus corniculatus) cv Leo and L. conimbricensis Willd. protoplasts. Birdsfoot trefoil etiolated hypocotyl protoplasts were inactivated with iodoacetate to inhibit cell division prior to fusion with L. conimbricensis suspension culture protoplasts. L. conimbricensis protoplasts divided to form callus which did not regenerate plants. Thus, plant regeneration from protoplast-derived callus was used to tentatively identify somatic hybrid cell lines. Plants regenerated from three cell lines exhibited additive combinations of parental isozymes of phosphoglucomutase, and L. conimbricensis-specific esterases indicating that they were somatic hybrids. The somatic chromosome number of one somatic hybrid was 36. The other somatic hybrid exhibited variable chromosome numbers ranging from 33 to 40. These observations approximate the expected combination of the birdsfoot trefoil (2n=4x=24) and L. conimbricensis (2n=2x=12) genomes. Somatic hybrid flowers were less yellow than birdsfoot trefoil flowers and had purple keel tips, a trait inherited from the white flowered L. conimbricensis. Somatic hybrids also had inflorescence structure that was intermediate to the parents. Fifteen somatic hybrid plants regenerated from the three callus lines were male sterile. Successul fertilization in backcrosses with birdsfoot trefoil pollen has not yet been obtained suggesting that the hybrids are also female sterile. This is the first example of somatic hybridization between these two sexually incompatible Lotus species.Formerly USDA-ARS, St. Paul, Minn, USA     

Genetic relationships between wild and cultivated Vicia ervilia (L.) Willd.

The wild form of bitter vetch, Vicia ervilia , grows mainly in Turkey. Wild and cultivated V. ervilia have the same chromosome number (2n =14), share the same karyotype and are interfertile. Pod dehiscence in V. ervilia is governed by two loci and the domesticated phenotype is obtained with the homozygous recessive condition in either locus.     

Arbuscular mycorrhizal fungi alter phosphorus relations of broomsedge (Andropogon virginicus L.) plants

Broomsedge (Andropogon virginicus L.) is a dominant grass revegetating many abandoned coal-mined lands in West Virginia, USA. Residual soils on such sites are often characterized by low pH, low nutrients, and high aluminium. Experiments were conducted to assess the resistance of broomsedge to limited phosphorus (Pi) availability and to investigate the role that arbuscular mycorrhizal (AM) fungi play in aiding plant growth under low Pi conditions. Pregerminated mycorrhizal and non-mycorrhizal seedlings were grown in a sand-culture system with nutrient solutions containing Pi concentrations ranging from 10 to 100 microM for 8 weeks. Non-mycorrhizal plants exhibited severe inhibition of growth under Pi limitation (<60 microM). Colonization by AM fungi (combined Glomus clarum Nicolson & Schenck and Gigaspora gigantea (Nicol. & Gerd.) Gerd. & Trappe) greatly enhanced host plant growth at low Pi concentrations, but did not benefit growth when Pi was readily available (100 microM). In comparison to non-mycorrhizal plants, mycorrhizal plants had higher phosphorus use efficiency at low Pi concentrations and maintained nearly constant tissue nutrient concentrations across the gradient of Pi concentrations investigated. Manganese (Mn) and sodium (Na) accumulated in shoots of non-mycorrhizal plants under Pi limitation. Mycorrhizal plants exhibited lower instantaneous Pi uptake rates and significantly lower C(min) values compared to non-mycorrhizal plants. These patterns suggest that the symbiotic association between broomsedge roots and AM fungi effectively maintains nutrient homeostasis through changes in physiological properties, including nutrient uptake, allocation and use. The mycorrhizal association is thus a major adaptation that allows broomsedge to become established on infertile mined lands.     

Distribution of Acacia senegal (L.) Willd. (Fabaceae) in Uganda and its relationship to climatic factors

The aim of the study was to map the distribution of Acacia senegal and its infraspecific taxa in Uganda and predict its suitable range of occurrence based on climatic factors. The distribution of the infraspecific taxa was analysed for richness, diversity, turnover and reserve selection. Regression analysis was performed to understand the relationship between distribution of the species and climatic variables. Georeferenced species occurrence points were superimposed over temperature and vapour maps. Areas with highest taxa richness, diversity and turnover were mapped and found in the Lake Kyoga basin. The species shows preference for the northern region of the study area with dissimilar climatic pattern from the southern region and the superimposition supported findings. Variety kerensis exhibited narrower climatic, altitudinal and distribution range preference. Temperature seasonality, maximum temperature of warmest month, temperature annual range, mean temperatures of warmest and driest quarters had the highest coefficients of determination (r² > 0.7) hence most important in influencing species distribution. The most appropriate locations for in situ conservation and for germplasm collection to ensure maximum diversity is secured are found in Wabisi‐Wajala, Kiula, Kyalubanga, Bajo, Kasagala, Kabwika‐mujwalanganda, Maruzi, Moroto and Napak Central Forest Reserves. The study recommends ecological studies to understand status of A. senegal.     

犬地卷[Peltigera canina(L.)Willd.]叶状体的光合速率与温度和湿度的关系

利用CID-310便携式光合作用测定系统,测定了叶状体地衣犬地卷[Peltigera canina(L.)Willd.]的光合速率及其与气候要素的关系,结果表明叶状体地衣的生长与湿度(水分)关系密切。犬地卷在长期进化的过程中,每日在日出后湿度最高的时刻,积极地进行光合作用;一天内最高光合速率在上午9:00~10.00时之间(东经87°地方时间为准),其余时间处于休眠状态,进行光合作用时温度的变化范围不大。     

Response of natural populations of predators and parasitoids to artificially induced volatile emissions in maize plants (Zea mays L.)

1 In response to herbivore attack, maize plants (Zea mays L.) emit a specific blend of induced volatiles. Artificial damage and subsequent treatment of the damaged site with caterpillar regurgitant induces the same response. The induced volatile chemicals are known to be highly attractive to several parasitoids of herbivores in laboratory bioassays, but very limited information is available on how the plant odours affect entomophagous insects in the field. 2 Experiments were conducted to determine if induced maize volatiles attract parasitic and predatory insects under field conditions and whether they affect their spatial distribution. 3 In a preliminary field experiment with blue sticky traps near treated (damaged and treated with caterpillar regurgitant) and healthy plants, more entomophagous insects (total number of parasitic Hymenoptera, Anthocoridae and Syrphidae) were trapped near treated plants than near healthy plants. 4 In a second experiment, attraction to the induced volatiles was monitored with sticky traps placed next to treated and healthy maize plants in a regular maize field. No significant differences between the two treatments were found, but significantly more insects (parasitic wasps, thrips and anthocorid bugs) were trapped near to the top of plants than on traps placed near the mid‐stem. Displacement of these insect groups within the field seemed to occur principally over the canopy, but under severe weather conditions they travelled lower in the canopy. 5 In a third experiment, the effect of induced maize odours on the spatial distribution of predators and parasitoids was investigated by placing sticky traps at different distances from healthy and treated plants. The higher catches of parasitoids near treated plants and the increased presence of these insects on the downwind side of treated plants support the notion that herbivore‐induced maize odours attract natural enemies of maize pests in the field.     

Development of transgenic pearl millet (Pennisetum glaucum (L.) R. Br.) plants resistant to downy mildew

Transgenic pearl millet lines expressing pin gene—exhibiting high resistance to downy mildew pathogen, Sclerospora graminicola—were produced using particle-inflow-gun (PIG) method. Shoot-tip-derived embryogenic calli were co-bombarded with plasmids containing pin and bar genes driven by CaMV 35S promoter. Bombarded calli were cultured on MS medium with phosphinothricin as a selection agent. Primary transformants 1T₀, 2T₀, and 3T₀ showed the presence of both bar and pin coding sequences as evidenced by PCR and Southern blot analysis, respectively. T₁ progenies of three primary transformants, when evaluated for downy mildew resistance, segregated into resistant and susceptible phenotypes. T₁ plants resistant to downy mildew invariably exhibited tolerance to Basta suggesting co-segregation of pin and bar genes. Further, the downy mildew resistant 1T₁ plants were found positive for pin gene in Southern and Northern analyses thereby confirming stable integration, expression, and transmission of pin gene. 1T₂ progenies of 1T₀ conformed to dihybrid segregation of 15 resistant:1 susceptible plants.     

Ecological differentiation and cladogenesis of Baldellia (L.) Parl. (Alismataceae)

The Iberian Peninsula is home to a large number of endemic species that often show strong genetic subdivisions which indicate possible isolation of populations in the past. Numerous phylogeographic and phylogenetic studies on Iberian flora and fauna have revealed this territory to be the origin of genetic differentiation during the Pleistocene Ice Age. To better understand the influence of Plio-Pleistocene climatic oscillations on the cladogenesis and population structuring of refugial taxa restricted to freshwaters of the Iberian Peninsula, we studied the evolutionary history of the small European genus Baldellia, both from a phylogenetic/phylogeographic perspective and regarding its ecological characteristics. Molecular analyses were based on four plastid regions and nuclear ITS2 ribosomal spacer from individuals belonging to geographically isolated Baldellia populations, while the relationships between climate and Baldellia species distribution was investigated by redundancy analysis applied to the climatic data with the occurrence of Baldellia species as external variables. The absence of a clear phylogenetic signal most likely reflects a common and recent cladogenesis for Baldellia. In contrast, the more rapidly evolving plastid sequences indicate a recent phylogeographic history of refugial repartition and ecological segregation probably occurring during the last glaciation, a scenario well supported by marked differences in species?? ecological preferences and climate analysis.     

Flower and nectar attributes of pepper (Capsicum annuum L.) plants in relation to their attractiveness to honeybees (Apis mellifera L.)

Flower morphology, nectary structure, nectar traits and rates of honeybee foraging on pepper plants were studied. The nectary appears as swellings on the basal part of the ovary. The nectariferous cells are smaller and denser than the neighbouring parenchyma. Stomata are present in the nectary epidermis, but do not appear on the other parts of the ovary epidermis. Seven pepper breeding lines were grown near a bee yard in Rehovot. Five to six fold differences in nectar volume were found between the extreme genotypes. Nectar volumes were higher during noon and afternoon hours, as compared with morning hours. High correlation coefficients between nectar volume and sugar concentration were found. These were significant for the four high nectar yielding genotypes, ranging between r = 0.65 to r = 0.94. Male-fertile flowers produced more nectar and higher sugar concentration than sterile ones. Skewed distribution was observed in nectar volume of F₂ populations, but relatively low heritability values were calculated. Pepper nectar contains fructose and glucose only. The former occupies 52–82 % of the total sugar content. Pepper genotypes varied in frequency of honeybee visits and significant correlation between sugar quantity and number of honeybee visits per flower was evident. Fertile pepper flowers are not very attractive to honeybees and male-sterile flowers are even less so. The considerable variation in nectar characteristics can be exploited to increase attractiveness to honeybees, thus facilitating bee pollination in commercial production of F₁hybrid seeds and improve fruit quality.