Glandularia X hybrida (Verbenaceae), a new combination for a common horticultural plant

A new combination,Glandularia x hybrida, and a lectotype are proposed for the common Garden Vervain (Verbena xhybrida). The plant is of horticultural origin, but occurs widely in North America and Mexico as an adventive.     

Detection of Nitric Oxide and Superoxide Radical Anion by Electron Paramagnetic Resonance Spectroscopy from Cells using Spin Traps

Reactive nitrogen/oxygen species (ROS/RNS) at low concentrations play an important role in regulating cell function, signaling, and immune response but in unregulated concentrations are detrimental to cell viability^{1, 2}. While living systems have evolved with endogenous and dietary antioxidant defense mechanisms to regulate ROS generation, ROS are produced continuously as natural by-products of normal metabolism of oxygen and can cause oxidative damage to biomolecules resulting in loss of protein function, DNA cleavage, or lipid peroxidation³, and ultimately to oxidative stress leading to cell injury or death⁴. Superoxide radical anion (O₂•-) is the major precursor of some of the most highly oxidizing species known to exist in biological systems such as peroxynitrite and hydroxyl radical. The generation of O₂•- signals the first sign of oxidative burst, and therefore, its detection and/or sequestration in biological systems is important. In this demonstration, O₂•- was generated from polymorphonuclear neutrophils (PMNs). Through chemotactic stimulation with phorbol-12-myristate-13-acetate (PMA), PMN generates O₂•- via activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase⁵. Nitric oxide (NO) synthase which comes in three isoforms, as inducible-, neuronal- and endothelial-NOS, or iNOS, nNOS or eNOS, respectively, catalyzes the conversion of L- arginine to L-citrulline, using NADPH to produce NO⁶. Here, we generated NO from endothelial cells. Under oxidative stress conditions, eNOS for example can switch from producing NO to O₂•- in a process called uncoupling, which is believed to be caused by oxidation of heme⁷ or the co-factor, tetrahydrobiopterin (BH₄)⁸.There are only few reliable methods for the detection of free radicals in biological systems but are limited by specificity and sensitivity. Spin trapping is commonly used for the identification of free radicals and involves the addition reaction of a radical to a spin trap forming a persistent spin adduct which can be detected by electron paramagnetic resonance (EPR) spectroscopy. The various radical adducts exhibit distinctive spectrum which can be used to identify the radicals being generated and can provide a wealth of information about the nature and kinetics of radical production⁹.The cyclic nitrones, 5,5-dimethyl-pyrroline-N-oxide, DMPO¹⁰, the phosphoryl-substituted DEPMPO¹¹, and the ester-substituted, EMPO¹² and BMPO¹³, have been widely employed as spin traps--the latter spin traps exhibiting longer half-lives for O₂•- adduct. Iron (II)-N-methyl-D-glucamine dithiocarbamate, Fe(MGD)₂ is commonly used to trap NO due to high rate of adduct formation and the high stability of the spin adduct¹⁴.     

Phylogenetic systematics of Colotis and associated genera (Lepidoptera: Pieridae): evolutionary and taxonomic implications

We investigated the genetic diversity and phylogenetic placement of the butterflies in the genus Colotis and eight related pierid genera using sequence information from two mitochondrial and two nuclear genes. To establish the status of species, we initially barcoded 632 specimens representative of all genera and most species and subspecies in those genera. A subset was then selected for phylogenetic analysis where additional gene regions were sequenced: 16S rRNA (523 bp), EF‐1α (1126 bp) and wg (404 bp). DNA barcode results were largely congruent with the traditional classification of species in the Colotis group, but deep splits or lack of genetic divergence in some cases supported either species‐level differentiation or synonymy. Despite using information from four genes, the deeper nodes in our phylogeny were not strongly supported, and monophyly of the ‘Colotis group’ and the genera Colotis and Eronia could not be established. To preserve the monophyly of Colotis, we revive the genus Teracolus for three outlying species previously in Colotis (i.e. Colotis eris, Colotis subfasciatus and Colotis agoye), as well as the genus Afrodryas for Eronia leda. The position of Calopieris is unresolved although it appears to be well outside the molecular variation in Colotis (s.l.). A dispersal/vicariance analysis suggested that major diversification in Colotis (s.str.) occurred in Africa with subsequent dispersal to India and Madagascar.     

No need to breed for enhanced colonization by arbuscular mycorrhizal fungi to improve low-P adaptation of West African sorghums

Background and aims

Herbaspirillum seropedicae (Hs) Z67 a diazotrophic endophyte was genetically engineered for secretion of 2-keto-D-gluconic acid by heterologous expression of genes for pqq synthesis and gluconate dehydrogenase to study its beneficial effect on plants.

Methods

Two plasmids, pJNK5, containing a 5.1 Kb pqq gene cluster of Acinetobacter calcoaceticus and pJNK6, carrying in addition the Pseudomonas putida KT2440 gluconate dehydrogenase (gad) operon were constructed in pUCPM18Gm^r under Plac promoter. H. seropedicae Z67 transformants were monitored for P and K solubilization, cadmium (Cd) tolerance and rice growth promotion.

Results

Hs (pJNK5) secreted 23.5 mM gluconic acid and Hs (pJNK6) secreted 3.79 mM gluconic acid and 15.8 mM 2-ketogluconic acid respectively. Under aerobic conditions, Hs (pJNK5) and Hs (pJNK6) solubilized 239.7 μM and 457.7 μM P on HEPES rock phosphate and, 76.7 μM and 222.7 μM K on HRPF (feldspar), respectively, in minimal medium containing 50 mM glucose. Under N free minimal medium, similar effects of P and K solubilization were obtained. Hs (pJNK5) and Hs (pJNK6) inoculation increased the biomass, N, P, K content of rice plants (Gujarat – 17). These plants also accumulated 0.73 ng/g PQQ, and had improved growth and tolerance to CdCl₂.

Conclusions

Incorporation of pqq and gad gene clusters in H. seropedicae Z67 imparted additional plant growth promoting traits of P and K solubilization and ability to alleviate Cd toxicity to the host plant.

     

Biosystematic studies inErythronium (Liliaceae-Tulipeae)

The floral biology ofErythronium japonicum has been studied from two approaches: a reinvestigation of its floral morphology and a pollinator case history. The perianth, differentiated into a sepal and petal cycle, has a tubular, but free arrangement basally around a slightly stipitate ovary. The two cycles of stamens with dimorphic filaments are positioned by the differently lobed auricles of the mature sepals and petals. These auricles also form a trap-lid mechanism for the inverted nectary which also has passageways. The perianth parts are highly UV absorbant due to the presence of flavonoids. This pattern contrasts strikingly with the purple trident basal guide lines so prominent in the visible spectrum. The weakly protandrous flowers also have exserted styles, thus functioning to exclude its own pollen and insure outbreeding. These floral adaptations are related specifically to the pollination behavior ofXylocopa appendiculata, and in general to the floral evolution within the genusErythronium. This work was supported in part by the U.S.-Japan Cooperative Science Program Grant GF-41367 and Grant-in-Aid No. 934053 from the Ministry of Education, Japan.