Effect of Temperature, Light, Nutrients and Dehardening on Abscisic Acid Induced Cold Hardiness in Bromus inermis Leyss Suspension Cultured Cells

The effects of culture conditions on abscisic acid (ABA)-inducedfreezing tolerance were determined in smooth bromegrass Bromusinermis Leyss cv. Manchar) cell suspension cultures. Bromegrasscultures initiated with 2 g fr wt of cells achieved maximumfreezing tolerances (greater than –32?C) at 25 to 30?Cin the presence of 75 to 100 µM ABA. High levels of freezingtolerance induced by ABA were correlated with high growth ratesat 25 and 30?C. In control cells, incubation at 10?C inducedoptimum levels of hardiness with minimal growth. Prolonged exposure(6 weeks) of cells to 3?C, with or without ABA, increased freezingtolerance only by several degrees. Exogenous ABA concentrationsgreater than 100 µM were not inhibitory to growth. Repeatedexposure to ABA, however, retarded growth and made the cellstolerant to temperatures below –40?C. Removal of ABA fromthe medium resulted in dehardening of the cells both at 25 and3?C. Nitrogen had a marginal effect on ABA-induced hardeningat 25?C, but inhibited age-dependent hardening of control cellcultures. Light had no effect on the freezing tolerance of culturedcells. Addition of 10% sucrose, 30 min prior to freezing, tobromegrass cells treated with ABA for 4 days increased freezingtolerance more than 15?C. These observations are discussed inrelation to the contrasting behaviour of the low temperatureand photoperiod dependent cold acclimation of plants (Received July 14, 1989; Accepted October 23, 1989)     

Improving efficiency of breeding for higher crop yield

Summary Exclusive selection for yield raises, the harvest index of self-pollinated crops with little or no gain in total bipmass. In addition to selection for yield, it is suggested that efficient breeding for higher yield requires simultaneous selection for yield's three major, genetically controlled physiological components. The following are needed: (1) a superior rate of biomass accumulation. (2) a superior rate of actual yield accumulation in order to acquire a high harvest index, and (3) a time to harvest maturity that is neither shorter nor longer than the duration of the growing season. That duration is provided by the environment, which is the fourth major determinant of yield. Simultaneous selection is required because genetically established interconnections among the three major physiological components cause: (a) a correlation between the harvest index and days to maturity that is usually negative; (b) a correlation between the harvest index and total biomass that is often negative, and (c) a correlation between biomass and days to maturity that is usually positive. All three physiological components and the correlations among them can be quantified by yield system analysis (YSA) of yield trials. An additive main effects and multiplicative interaction (AMMI) statistical analysis can separate and quantify the genotype × environment interaction (G × E) effect on yield and on each physiological component that is caused by each genotype and by the different environment of each yield trial. The use of yield trials to select parents which have the highest rates of accumulation of both biomass and yield, in addition to selecting for the G × E that is specifically adapted to the site can accelerate advance toward the highest potential yield at each geographical site. Higher yield for many sites will raise average regional yield. Higher yield for multiple regions and continents will raise average yield on a world-wide basis. Genetic and physiological bases for lack of indirect selection for biomass from exclusive selection for yield are explained.     

A phylogenomic tree inferred with an inexpensive PCR-generated probe kit resolves higher-level relationships among Neptis butterflies (Nymphalidae: Limenitidinae)

Recent advances in obtaining reduced representation libraries for next-generation sequencing permit phylogenomic analysis of species-rich, recently diverged taxa. In this study, we performed sequence capture with homemade PCR-generated probes to study diversification among closely related species in a large insect genus to examine the utility of this method. We reconstructed the phylogeny of Neptis Fabricius, a large and poorly studied nymphalid butterfly genus distributed throughout the Old World. We inferred relationships among 108 Neptis samples using 89 loci totaling up to 84 519 bp per specimen. Our taxon sample focused on Palearctic, Oriental and Australasian species, but included 8 African species and outgroups from 5 related genera. Maximum likelihood and Bayesian analyses yielded identical trees with full support for almost all nodes. We confirmed that Neptis is not monophyletic because Lasippa heliodore (Fabricius) and Phaedyma amphion (Linnaeus) are nested within the genus, and we redefine species groups for Neptis found outside of Africa. The statistical support of our results demonstrates that the probe set we employed is useful for inferring phylogenetic relationships among Neptis species and likely has great value for intrageneric phylogenetic reconstruction of Lepidoptera. Based on our results, we revise the following two taxa: Neptis heliodore comb. rev. and Neptis amphion comb. rev.     

Amino acid sequence of the nonsecretory ribonuclease of human urine

The amino acid sequence of a nonsecretory ribonuclease isolated from human urine was determined except for the identity of the residue at position 7. Sequence information indicates that the ribonucleases of human liver and spleen and an eosinophil-derived neurotoxin are identical or very closely related gene products. The sequence is identical at about 30% of the amino acid positions with those of all of the secreted mammalian ribonucleases for which information is available. Identical residues include active-site residues histidine-12, histidine-119, and lysine-41, other residues known to be important for substrate binding and catalytic activity, and all eight half-cystine residues common to these enzymes. Major differences include a deletion of six residues in the (so-called) S-peptide loop, insertions of two, and nine residues, respectively, in three other external loops of the molecule, and an addition of three residues at the amino terminus. The sequence shows the human nonsecretory ribonuclease to belong to the same ribonuclease superfamily as the mammalian secretory ribonucleases, turtle pancreatic ribonuclease, and human angiogenin. Sequence data suggest that a gene duplication occurred in an ancient vertebrate ancestor; one branch led to the nonsecretory ribonuclease, while the other branch led to a second duplication, with one line leading to the secretory ribonucleases (in mammals) and the second line leading to pancreatic ribonuclease in turtle and an angiogenic factor in mammals (human angiogenin). The nonsecretory ribonuclease has five short carbohydrate chains attached via asparagine residues at the surface of the molecule; these chains may have been shortened by exoglycosidase action.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seasonal Changes in Plasma Membranes and Mitochondria Isolated From Jerusalem Artichoke Tubers. Possible Relationship to Cold Hardiness

Plasma membranes and mitochondria were isolated from Jerusalemartichoke tubers during cold acclimation from September to December.The protein and lipid contents of the membranes were analyzedwith reference to physiological properties of the tubers, especiallycold hardiness. As cold hardiness increased from autumn to winter,the content of phospholipids and sterols on a mg protein basisincreased by 20–30% in plasma membranes, but little changewas observed in mitochondria. Minor changes were observed inthe fatty acid composition of phospholipids either in plasmamembranes or mitochondria. Membrane fluidity, assessed by fluorescentpolarization of 1,6-diphenyl-1,3,5-hexatriene, was found tobe relatively constant in both membranes during the season.One dimensional SDS-polyacrylamide gel electrophoresis revealedseasonal changes in proteins and glycoproteins in plasma membranes,but not in mitochondrial membranes. Plasma membrane ATPase increasedin specific activity from September to December, which was morenoticeable at higher assay temperatures. However, irrespectiveof the season, the plasma membrane ATPase had an inflectionon the slope of the Arrhenius plot around 15C. These resultssuggest that plasma membranes, in contrast to mitochondria,undergo several molecular changes from autumn to winter, whichmay be related to cold acclimation of the tubers. ¹ Contribution No. 2668 from the Institute of Low TemperatureScience. ² Present address: Crop Development Centre, University of Saskatchewan,Saskatoon, Canada S7N 0W0.     

Comparative studies of the vascular system of node-leaf continuum in woody ranales

The vascularization of the node-leaf continuum in the first to eighth foliage leaves of the first-year plant ofMagnolia virginiana is investigated. The cotyledonary node is a 4-trace, 3-lacunar type. Vascularization in the cotyledonary node is fundamentally different from that in the folair node of the same plant. As a result, the cotyledonary vascularization is only described but not compared to that in the foliar node-leaf continuum. Considerable diversity occurs in the node-leaf vascularization of the first-year plants. A 5-trace, 4-lacunar vascular system is constant in the lower folair nodes; this is considered to be the fundamental vascular pattern in the node-leaf continuum of the species. In contrast, the nodal anatomy and petiolar vascularization fluctuate widely in the third to eighth leaves of the first-year plants. Variation is found not only between different nodes of a single plant but even in the corresponding nodes of different individuals. The evidence clearly indicates that variation always correlates with certain members of the leaf-trace complement; thus, either the ventral and/or marginal lateral bundles undergo phylogenetical reduction or amplification.