Structural Attributes of the Hypogeous Holoparasite Hydnora Triceps Drège & Meyer (Hydnoraceae)

The morphology of the hypogeous root holoparasite Hydnora triceps is highly reduced, and as with many holoparasites, the vegetative body is difficult to interpret. The vegetative body of H. triceps has been historically considered a pilot root studded with lateral appendages known as haustorial roots. We found the vegetative body of H. triceps to consist of a rhizome with a thickened root-cap-like structure that covered a vegetative shoot apical meristem. From the apical meristem, procambial strands originated and developed into endarch collateral vascular bundles arranged radially around a pith without an interfascicular cambium. Xylem vessels had scalariform pitting and simple perforation plates. A continuous periderm without root hairs was observed. Increase in girth was attributed to cork and fascicular cambia. Haustorial roots or bumps on the surface of the vegetative body were exogenous, contained meristems and were the origins of vegetative branching, budding, and haustoria. The haustoria of H. triceps were cylindrical and penetrated the host root stele. Phloem and xylem elements were observed within the endophyte, and direct xylem to host-xylem contacts were observed. The arrangement of vascular tissues and xylem anatomy of H. triceps are likely plesiomorphic features in light of Hydnoraceae\u27s placement in the Piperales

Comparative Study on Growth Performance of Transgenic (Over-Expressed OsNHX1) and Wild-Type Nipponbare under Different Salinity Regimes

Transgenic Nipponbare which over-expressed a Na+/H+ antiporter gene OsNHX1 was used to compare its growth performance, water status and photosynthetic efficiency with its wild type under varying salinity regimes. Chlorophyll content, quantum yield and photosynthetic rate were measured to assess the impact of salinity stress on photosynthetic efficiency for transgenic and wild-type Nipponbare. Effects of salinity on water status and gas exchange to both lines were studied by measuring water use efficiency, instantaneous transpiration rate and stomatal conductance. Dry shoot weight and leaf area were determined after three months of growth to assess the impacts of salinity on the growth of those two lines. Our study showed that both lines were affected by salinity stress, however, the transgenic line showed higher photosynthetic efficiency, better utilization of water, and better growth due to low transpiration rate and stomatal conductance. Reduction of photosynthetic efficiency exhibited by the wild-type Nipponbare was correlated to its poor growth under salinity stress

Haustorium-related uptake and metabolism of host xylem solutes by the root hemiparasitic shrub Santalum acuminatum (R. Br.) A. DC. (Santalaceae)

Solute composition of root xylem sap of common native hosts of quandong (Santalum acuminatum) was compared with that of corresponding xylem sap and ethanolic extracts of endophytic tissues of haustoria of the hemiparasite. Each host transported a characteristic set of organic nitrogenous solutes, but little or no nitrate, and the data indicated only limited direct flow of amino compounds between xylem streams of hosts and parasite. Proline predominated in the haustorium and xylem of Santalum, but was at negligible levels in the xylem of most hosts. Sucrose, fructose, glucose, malate and citrate were at high levels in all saps, and fructose especially prominent in Santalum. Chloride, sulphate and phosphate were the principal inorganic anions of the xylem. Based on C:N ratios of xylem and dry matter of Santalum and assuming a 70% or more dependence on the host for N, it was estimated that Santalum would gain approximately one third of its C requirement for dry matter production heterotrophically from the xylem of its hosts. Infiltration of xylem of haustoria-bearing root segments of a major host (Acacia rostellifera) with a range of N labelled substrates resulted in 40-80% of the N of endophytes of the attached haustoria being received as proline. Nitrate reductase activity was induced in haustoria following host xylem feeding of nitrate. The study concludes that haustoria of Santalum act as a major site of synthesis and export of proline and might therefore play an important role in osmotic adjustment of the parasite and its related acquisition of water from hosts

Germination Strategy of <i>Chenopodium acuminatum</i> Willd. under Fluctuating Salinity Habitats

Germination events of plants often occur after rainfall in saline environments where the soil salinity is diluted, viz recovery germination. Previous germination studies have rarely considered the duration of exposure to salt stress, and none of them have investigated recovery germination under low-salt concentration, other than in distilled water. The main objective of this study was to investigate the effects of salinity, exposure duration and low-salt recovery solutions on seed germination of the weed Chenopodium acuminatum to get a clear insight about the germination strategy exhibited by this species in a saline habitat. Seeds were initially exposed to 0–400 mM NaCl for 10, 20 and 30 d. The subsequent recovery experiment was conducted differently. For those initially treated with 100 and 200 mM NaCl, the recovery solution was distilled water, while for those initially treated with 300 and 400 mM NaCl, the recovery solution was distilled water, at 50 and 100 mM NaCl. Results showed that the recovery germination percentage and rate significantly decreased when the exposure duration extended. Seeds could subsequently recover to germinate at high percentages at recovery salt solution concentrations for a short duration, but the recovery percentages and rates in high salinity, combined with high exposure duration and relatively high recovery salt concentrations, were remarkably lower. More than 30% of the ungerminated seeds were viable after the recovery experiment. We suggest that Ch. acuminatum exhibits a ‘cautious’ strategy of germination to avoid injury from long-term salt stress and ensure survival for the subsequent continuation of its population under unfavorable saline conditions

Changes in Soil Physicochemical and Water Properties in Response to Exotic Acacia Invasion in a Bornean Coastal Heath Forest

This study investigates the impacts of Acacia invasion on Bornean heath forest (HF) soils. Soil profiles and water properties at one soil depth (< 1 m) and physicochemical properties with Soil Fertility Index(SFI) and Soil Evaluation Factor (SEF) from the topsoil or three soil depths of Acacia-invaded and non-invaded HF were assessed. Acacia invasion modified soil profiles by producing thicker horizons O and B but waning horizon E. Thick leaf litter layer in invaded HF was associated with a significant decrease in soil bulk density, moisture, organic matter (OM), total organic carbon, water volume, and NH4+ but a significant increase in soil temperature, and soil water pH, NO3− and PO43−. A significant increase in soil pHwater and available P were observed across all depths, except for topsoil exchangeable NH4+. Acacia invasion significantly reduced total acidity and base cations across soil depths, and total N and exchangeable H, NO3−, Mg, and Al at certain depths, implying leaching and reduced acidification. Topsoil SFI and SEF of Acacia-invaded HF were significantly lower than non-invaded HF, possibly due to slower decomposition rates resulting in lower OM and base concentrations. Variations in topsoil physicochemical properties generated two distinct clusters with the Acacia-invaded plots strongly influenced by PC1 (exchangeable soil NH4+ and temperature), while the non-invaded plots were strongly influenced by PC2 (pHKCl, total acidity, exchangeable Ca, H, and Al). Acacia invasion negatively impacted soil properties, potentially affecting plant, soil, and microbial communities, thus indicating that invasion mitigation and ecological restoration efforts should be prioritized for the invaded HF

Equilibrium Isotherm Studies of Adsorption of Pigments Extracted from Kuduk-kuduk (Melastoma malabathricum L.) Pulp onto TiO2 Nanoparticles

The adsorption of natural pigments onto TiO2 nanoparticles was investigated. The pigments were extracted from the dark purple colored pulp of the berry-like capsule of Kuduk-kuduk (Melastoma malabathricum L.). The Langmuir, Freundlich, Redlich-Peterson, and Sips isotherm models were used to analyze the equilibrium experimental data. Data correlated well with the Sips isotherm model, where the heterogeneity factor (n=0.24) indicated heterogeneous adsorption characteristics, with a maximum adsorption capacity of 0.0130 mg/g. The heterogeneous adsorption character was further supported by results obtained from zeta-potential measurements. When a dye-sensitized solar cell (DSSC) was sensitized with the extracted pigment, the photo-energy conversion efficiency was measured to be 0.83%, thus proving the suitability of Kuduk-kuduk fruit pulp as a sensitizer in DSSCs

Parasitic Mistletoes of the Genera Scurrula and Viscum: From Bench to Bedside

The mistletoes, stem hemiparasites of Asia and Europe, have been used as medicinal herbs for many years and possess sophisticated systems to obtain nutrients from their host plants. Although knowledge about ethnomedicinal uses of mistletoes is prevalent in Asia, systematic scientific study of these plants is still lacking, unlike its European counterparts. This review aims to evaluate the literature on Scurrula and Viscum mistletoes. Both mistletoes were found to have anticancer, antimicrobial, antioxidant and antihypertensive properties. Plants from the genus Scurrula were found to inhibit cancer growth due to presence of phytoconstituents such as quercetin and fatty acid chains. Similar to plants from the genus Viscum, Scurrula also possesses TNFα activity to strengthen the immune system to combat cancer. In line with its anticancer activity, both mistletoes are rich in antioxidants that confer protection against cancer as well as neurodegeneration. Extracts from plants of both genera showed evidence of vasodilation and thus, antihypertensive effects. Other therapeutic effects such as weight loss, postpartum and gastrointestinal healing from different plants of the genus Scurrula are documented. As the therapeutic effects of plants from Scurrula are still in exploration stage, there is currently no known clinical trial on these plants. However, there are few on-going clinical trials for Viscum album that demonstrate the functionalities of these mistletoes. Future work required for exploring the benefits of these plants and ways to develop both parasitic plants as a source of pharmacological drug are explained in this article