Effects of genotype,habitat, and seasonal variation on iridoid glycoside content of Plantago lanceolata (Plantaginaceae) and the implications for insect herbivores

Summary We investigated the effects of genotype, habitat, and seasonal variation on production of the iridoid glycosides, aucubin and catalpol, in leaves of the common weed Plantago lanceolata. Two genotypes, one each from a lawn and an adjacent abandoned hayfield population, were clonally replicated in the greenhouse, and then planted back into the two habitats. One quarter of the plants from each treatment were harvested on each of four dates, at approximately two-week intervals. Over the course of the growing season, and in both habitats, we found a significant increase in the concentration of both aucubin and catalpol in P. lanceolata leaves. The genotypes differed in their response to environmental variation, both in time and between sites, as indicated by significant genotype x date and genotype x site interactions. Early in the season, habitat (lawn or field) had a greater effect on iridoid glycoside concentration than did plant genotype, but later in the season, plant genotype was more influential in determining the iridoid glycoside concentration. Thus, the relative palatability of Plantago genotypes to specialist and generalist herbivores may vary in time and space.     

Classifying genotypic data from plant breeding trials: a preliminary investigation using repeated checks

Summary Several subjective choices must be made when classifying genotypes based on data from plant breeding trials. One choice involves the method used to weight the contribution each environment makes to the classification. A second involves the use of either genotype-means for each environment or genotypevalues for each block, i.e., considering each block to be a different environment. Another involves whether environments (or blocks) in which genotypes are nonsignificantly different should be included or excluded from such classifications. An alternative to the use of raw or standardized data, is proposed in which each environment is weighted by a discrimination index (DI) that is based on the concept of repeatability. In this study the effect of three weighting methods (raw, standardized and DI), the choice of using environments or blocks, and the choice of including or excluding environments or blocks in which genotypic effects were not significant, were considered in factorial combination to give 12 options. A data set comprised of five check cultivars each repeated six times in each of three blocks at six environments was used. The effect of these options on the ability of a hierarchical clustering technique to correctly classify the repeats into five groups, each consisting of all the six repeats of a particular check cultivar, was investigated. It was found that the DI weighting method generally led to better recovery of the known structure. Using block data rather than environmental data also improved structure recovery for each of the three weighting methods. The exclusive use of environments in which genotypic effects were significant decreased structure recovery while the contrary generally occurred for blocks. The best structure recovery was obtained from the DI weighting applied to blocks (whether genotypes were significant or not).     

Site-specific oligodeoxynucleotide binding to maize Adh1 gene promoter represses Adh1-GUS gene expression in vivo

There is a 36 bp tract of extreme homopurine/homopyrimidine (PuPy) asymmetry in the maize Adh1 gene promoter (from –44 to –79) that is S1-hypersensitive in plasmids under supercoil tension. Oligodeoxynucleotides corresponding to the PuPy tract were designed to examine the secondary structure of the region and address the possible role of the tract in gene regulation. On the basis of oligodeoxynucleotide band-shift and DNase I footprinting analyses, it was concluded that the homopyrimidine oligodeoxynucleotide can form a triple helix with the duplex PuPy tract in vitro. Transient assays in protoplasts, suspension cells, and seedling roots show that the homopyrimidine oligodeoxynucleotide is also capable of repressing Adh1-GUS gene expression during co-transformation, presumably by the formation of a triple helix with the PuPy tract in vivo. The complementary homopurine oligodeoxynucleotide would not form a triple helix in vitro, nor would it repress Adh1-GUS in vivo. We propose that triple helix formation is a potential regulatory phenomenon in vivo, and that an intraregion triple helix could occur within the Adh1 promoter via the formation of H-DNA.     

Effects of serial subculture in vitro on the endogenous levels of indole-3-acetic acid and abscisic acid and rootability in microcuttings of ‘Jonathan’ apple

Proliferating axillary shoots of the difficult-to-root apple cultivar Jonathan acquired an enhanced ability to form adventitious roots with increasing number of subcultures in vitro. The transition between the difficult-to-root and the easy-to-root condition occurred at the fourth subculture.Endogenous levels of free IAA and ABA in shoot tissues were analysed by gas chromatography/mass spectrometry/single ion monitoring (GC/MS/SIM) using negative ion chemical ionisation. Tissues from the mother plants grown in the glasshouse contained more IAA and ABA than those from tissue-culture material. After establishment in vitro there was no variation in the IAA content throughout the subcultures but a decrease in ABA content was observed after the fourth transfer. The IAA/ABA ratio increased from 0.2 in difficult-to-root shoots from the initial culture up to 0.7 in easy-to-root shoots from the long-term subculture.     

RNA Polymerase B levels during the cell cycle ofPhysarum polycephalum

Summary Tritiated -amanitin has been used as a specific and sensitive probe to estimate the number of RNA polymerase B molecules in isolated nuclei, chromatin and nucleoids, obtained from macroplasmodia ofPhysarum polycephalum. During mitosis (metaphase±10 min) there is at least 10-fold less RNA polymerase B than at all phases of the cell cycle, even if DNA replication has been blocked in vivo. It is concluded that many of the RNA polymerase B molecules leave the chromatin during decondensation of the chromosomes in telophase of the synchronous nuclear division ofPhysarum.     

Effect of γ-hexachloran and sevin on the survival of the Black Sea mussel,Mytilus galloprovincialis Lam

Some observations on the effect of -hexachloran and sevin on the survival of two size groups of the Black Sea mussel, Mytilus galloprovincialis Lam. were made. The results of the present study are compared with those made earlier on the same species and on fishes.     

A histochemical study of the binding of 125I-HCG to the rat ovary throughout the estrous cycle

Summary Changes in the distribution of the in vitro uptake of ¹²⁵I-HCG by the ovaries of adult rats were examined histochemically throughout the estrous cycle.Only in follicles wider than 500 m, occurring mainly at diestrus and proestrus, could granulosa cells bind the labelled hormone. The labelling increased with follicular size and decreased in intensity from the peripheral granulosa cells inwards. No uptake occurred in the oocytes, in the cells of the cumulus oophorus nor in the granulosa cells of the atretic follicles.The binding capacity of the newly-formed corpora lutea of estrus was less than that of preovulatory follicles. The uptake of ¹²⁵I-HCG by corpora lutea during the first cycle reached its maximum at diestrus but fell sharply by proestrus. The uptake was patchy in the corpora lutea of the second cycle and not significant in the older ones.The uptake of ¹²⁵I-HCG by thecae increased with follicular size and was greater in the thecae of atretic follicles than in the thecae of growing follicles of like size. There was a greater uptake in the last formed interstitial tissue than there was in older tissue.At proestrus, the uptake of ¹²⁵I-HCG was unaffected by the LH surge at 18.00h but had decreased slightly at 24.00 h.The implications of these data in relation to the regulation of receptor sites, is discussed.     

Chemical separation of helper cell function and delayed hypersensitivity responses

Studies were performed to investigate the effects of the immunosuppressive chemical TCDD. Fetal and neonatal rats were exposed to TCDD through maternal dosing (5 μg/Kg) at Day 18 of gestation and on Days 0, 7, and 14 of postnatal life. Another group of neonatal rats were exposed to TCDD through maternal dosing on Days 0, 7, and 14 of postnatal life only. Parameters of cell-mediated and humoral immune function were investgiated. TCDD suppressed delayed hypersensitivity responses and responses to the mitogens Con A and PHA without affecting humoral immune function. Suppression of T-cell function was selective in that helper function was not suppressed. Transfer of primed T-lymphocytes from TCDD treated and non-treated animals into neonatally thymectomized animals confirmed this. Results indicate that delayed hypersensitivity function and helper function reside in distinct T-cell subsets.     

Regulation of adenosine-5′-phosphosulfate sulfotransferase activity by H2S in Lemna minor L.

When Lemna minor L. is transferred to an atmosphere with H₂S, there is a rapid loss of extractable adenosine-5-phosphosulfate sulfotransferase activity. The activity is restored within 24 h in an atmosphere without H₂S. This restoration of activity is completely inhibited by cycloheximid but not by chloramphenicol. In vitro, S^2- up to 5 mM and cysteine, methionine, and glutathione up to 50 mM do not inhibit the enzyme. The activities of ATP sulfurylase and O-acetyl-L-serine sulfhydrylase are not affected significantly by H₂S. The physiological significance of the regulation of adenosine-5-phosphosulfate sulfotransferase is discussed.Abbreviations APS adenosine-5-phosphosulfate - PAPS adenosine-3-phosphate-5-phosphosulfate - BSA bovine serum albumin - DTT dithiothreitol - POPOP 1,4-di [2-(5-phenyloxazolyl)]-benzene - PPO 2,5-diphenyloxazol This is no. 6 in the series Regulation of Sulfate Assmilation in Plants     

Flavonoid data and populational observations in support of hybrid status for Populus acuminata

Flavonoid distribution and populational composition at the collection sites of several samples of Populus acuminata strongly suggest that this taxon is an inter-sectional hybrid between P. angustifolia, sect. Tacamahaca and any one of two or three different species of the section Aigeiros, when the entire range is considered. In the vicinity of the type locality, the Aigeiros parent is P. sargentii. Within any population, foliage of trees of P. acuminata is characterized by morphological intermediacy and an essentially additive flavonoid profile, as compared to the two parental taxa present. In habit the trees resemble those of P. sargentii, and habitats at the collection sites were found to be somewhat intermediate. Fifteen flavonoid compounds were consistently present in samples of the putative hybrid. Twelve of these had diagnostic value because they were absent in one of the parental species. One compound, apigenin 7-O-diglucoside, was found only in P. acuminata. In part, our identifications correspond to compounds reported by Crawford in a morphological and chemical study of P. acuminiata.