Early fungal community succession following crown fire in Pinus mugo stands and surface fire in Pinus sylvestris stands

The early post-fire development of mycobiota following a crown fire in mountain pine plantations and a surface fire in Scots pine plantations, and in the corresponding unburnt stands in the coastal sand dunes of the Curonian Spit in western Lithuania was investigated. Species numbers in unburnt Pinus mugo and Pinus sylvestris stands showed annual fluctuation, but in the burnt sites, the numbers of fungi increased yearly, especially in the crown fire plots. Both burnt stand types—P. mugo and P. sylvestris—showed strongly significant (two-way ANOSIM; R = 1, p < 0.05) differences in species composition; the differences between unburnt sites were clearly expressed but less significant (R = 0.86, p < 0.05). Fungal species composition of burnt P. mugo and P. sylvestris sites was qualitatively different from that of corresponding unburnt sites (two-way ANOSIM; R ≥ 0.75, p < 0.05). The chronosequence of mycobiota in surface fire burns was less clearly defined than in crown fire sites, reflecting the greater patchiness of impacts of the surface fire. Although both fire types were detrimental or at least damaging to all functional groups of fungi (saprobic on soil and forest litter, wood-inhabiting, biotrophic, and mycorrhizal and lichenized fungi), their recovery and appearance (fructification) patterns varied between the groups and among the burn types. The end of the early post-fire fungal succession (cessation of sporocarp production of pyrophilous fungi) was recorded 3 years after the fire for both crown and surface fire types, which is earlier than reported by other authors. Rare or threatened fungal species that are dependent on fire regime were not recorded during the study.     

Reconstruction of Current Flow and Imaging of Current-Limiting Defects in Polycrystalline Superconducting Films

Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.     

Chromium stress alleviation by salicylic acid in Malabar spinach (Basella alba)

Abstract

Phytoremediation is a natural approach to use plants for decontaminating soil. A pot-culture factorial experiment in completely randomized design was conducted to evaluate the effects of four levels [0, 25, 50, and 100?mg/kg] of chromium (Cr) with three levels [0, 0.5, and 1-M solution) of plant defense inducer salicylic acid (SA) on growth, physiological processes, and biochemical responses of Malabar spinach (Basella alba). Results showed that Cr significantly decreased vine length (VL), leaf number (LN), leaf area (LA), fresh- (FBM), and dry-biomass (DBM), root length (RL), and dry-matter ratio (DMR). Cr also significantly decreased SPAD (chlorophyll contents), by 9% to 29% and net photosynthesis (Pn) rates, by 36% to 71%, but increased transpiration (E) rates, by 1.5 to 2.7 times and stomatal conductance (C), by 1.7 to 3.5 times, as compared with the control. Proline contents increased with an associated decrease in oxidative enzyme activities such as peroxidase, (POD) and catalase, (CAT) with increasing Cr levels. Cr significantly reduced the Dry Matter Ratio (DMR) (12% to 42%) and LA (10% to 35%), RL -stress (11% to 27%), and SPAD (10% to 28%) stress tolerance indices. The integrated stress tolerance index (IST_Index) of Malabar spinach was reduced (by 6% to 23%) by Cr stress, as compared to the control. SA application, in contrast, partially alleviated the severity of Cr toxicity effects on VL, LN, LA, FBM, DBM, RL, and DMR and increased the SPAD (by 12%), Photosynthesis Net (Pn) (by 53% to 68%), and stomatal conductance (C) (by 35% to 50%), respectively. Furthermore, SA increased plant stress tolerance indices by increasing antioxidant enzymatic functions. SA application recovered the IST_Index at all Cr levels, and the recovery effect on plants was more pronounced by 0.5-M SA than by other SA treatments. The mechanism of stress tolerance as induced by SA application may help plants to better survive and maintain growth in presence of higher Cr contents in soil. Results suggested that SA, as a plant defense inducer, can be exploited for improving Cr phytoremediation potential of Malabar spinach to decontaminate soil.     

Molecular and phenotypic diversity of ICARDA spring barley (<Emphasis Type="Italic">Hordeum vulgare</Emphasis> L.) collection

Plant breeders are interested in using diverse genotypes in hybridization that can segregate for traits of importance with possibility of selection and genetic gain. Information on molecular and agro-morphological diversity helps the breeders reduce the effort for parental selection and helps the advancement of generations. A phenotypic and molecular diversity study, using 24 traits (agronomic and disease) and 6519 SNPs in a diverse collection of 336 spring barley genotypes, was carried out at Marchouch and Jemma Shiam research stations in Morocco. Based on structure and multivariate analyses, strong differentiation between the two- and six-row types were observed. The linkage disequilibrium (LD) decay of the current collection (for the combined population) was up to 3.58 cM (r ² = 0.15) while LD decay were estimated 3.91 and 2.36 cM for two- and six-row barley, respectively. PCA of agro-morphological traits revealed grain per spike, net form of net blotch (NFNB), spot form of net blotch (SFNB), and 1000 kernel weight were the most discriminatory traits in the current collection. Association mapping in the two independent populations will be ideal for identification of markers, and QTL related to traits. The generated information on relatedness between individuals will help identify diverse genotypes for breeding programs.     

Molecular Architecture and Biomedical Leads of Terpenes from Red Sea Marine Invertebrates

Marine invertebrates including sponges, soft coral, tunicates, mollusks and bryozoan have proved to be a prolific source of bioactive natural products. Among marine-derived metabolites, terpenoids have provided a vast array of molecular architectures. These isoprenoid-derived metabolites also exhibit highly specialized biological activities ranging from nerve regeneration to blood-sugar regulation. As a result, intense research activity has been devoted to characterizing invertebrate terpenes from both a chemical and biological standpoint. This review focuses on the chemistry and biology of terpene metabolites isolated from the Red Sea ecosystem, a unique marine biome with one of the highest levels of biodiversity and specifically rich in invertebrate species.     

Tree-grass coexistence in a flood-disturbed, semi-arid savanna system

The coexistence of trees and grasses in savanna ecosystems is a contentious phenomenon. Fire and herbivory disturbances are often cited as major structuring forces that create a sustainable tree–grass relationship. However, periodic flooding of savanna patches may also enable coexistence. The aim of this study was to investigate the effects of flood-disturbance on the recruitment patterns of Acacia karroo trees in a semi-arid savanna system in South Africa. We analysed the spatial coincidence of A. karroo seedlings with tussocks of the tall spiny grass Stipagrostis namaquensis in the riverbed and related herbivory intensity to spatial position. The data showed that A. karroo seedlings were significantly positively associated with S. namaquensis (Chi-square test, $ \chi_{1}^{2} = 4 5. 20 $ , n = 118, P < 0.001); A. karroo seedlings growing inside of tussocks experienced less browsing pressure than those growing in the floodplain (Kruskal–Wallis test, H = 11.90, n = 118, P < 0.01); and recruitment success of A. karroo trees was spatially discrete (K–S test, D = 0.78, n = 196, P < 0.01). We suggest that floods create an enemy-free zone, which S. namaquensis colonises and then facilitates successful A. karroo establishment. High levels of A. karroo recruitment in the riverbed may replenish the woodlands fringing the river, which appear to be sink areas for A. karroo seedlings. Thus, the interaction between disturbances at different spatial and temporal scales (flooding versus herbivory) seems to maintain the inherently unstable coexistence of tree and grass species in this ecosystem. These findings also suggested that flood disturbances alter the tree–grass relationship.     

Induced responses to herbivory and increased plant performance

Plant resistance to herbivores was induced in a field experiment to evaluate the consequences of induced responses for subsequent herbivory and plant fitness. Induction early in the season resulted in halving of herbivory by chewing herbivores and a reduction in the abundance of phloem-feeding aphids when compared with controls. A correlate of lifetime plant fitness, seed mass, was enhanced by over 60 percent for individuals that were induced.     

Physiological and biochemical responses of two faba bean (Vicia faba L.) varieties grown in vitro to salt stress

Journal of Crop Science and Biotechnology - Faba bean (Vicia faba L.) is one of the most important legume crops worldwide. High salinity is a major constraint for faba bean productivity in many...