Alina Wiszniewska

Natural Organic Amendments for Improved Phytoremediation of Polluted Soils: A Review of Recent Progress

Abstract Environmental pollution caused by metals, radionuclides and organic pollutants affects quality of the biosphere: soil, water and air. Currently, great efforts have been made to reduce, remove or stabilize contaminants in polluted sites. There has been increasing interest in phytoremediation—the use of plants to reduce concentration of pollutants or to render them harmless. This paper provides a brief review of recent progress in the research and practical application of phytoremediation techniques. Improvements in phytoremediation due to utilization of organic amendments, namely, agro- and industrial wastes (such as sugar beet residue, composted sewage sludge or molasses), biochar, humic substances, plant extracts and exudates are discussed, as well as their influences on soil structure and characteristics, plants growth and bioavailability of pollutants. Both plant-assisted phytoremediation and the use of natural materials in the absence of remediating plant are believed to be cost-effective and environmentally friendly approaches for soil cleanup. However, the characterization and quantification of a range of natural materials used in phytoremediation are essential in order to implement these approaches to practice.

Improvement in Lupinus luteus (Fabaceae) protoplast culture – stimulatory effect of agarose embedding and chemical nursing on protoplast divisions

Comprehensive studies were undertaken to determine optimal conditions for yellow-lupin (Lupinus luteus L.) protoplast culture. The adopted isolation procedure resulted in a high yield of protoplasts obtained from hypocotyls, cotyledons and young leaves. The usefulness of liquid and agarose-solidified media was evaluated in relation to promoting survivability and morphogenetic responses of protoplasts. The influence of different plant-growth regulators and anti-oxidative agents was also examined. Cultivar ‘Parys’ was the most promising material for manipulations. The solidification of medium enhanced the development of cultures initiated from hypocotyls and cotyledons, significantly increasing the division rate. In both liquid and solid media, mitoses were arrested after the initial division and daughter cells failed to divide. An important breakthrough in the development of cultures appeared in media supplemented with 0.1% activated charcoal. Bypassing the mitosis suppression led to the formation of small aggregates from hypocotyl protoplasts. This is the first report on protocolony formation in protoplast cultures of L. luteus. Notable progress achieved here indicates that, although this species is considered as recalcitrant to in vitro manipulations, it is possible to obtain responsive cultures with higher morphogenetic potential and thus provide new material for breeding programs of lupins.

Recent strategies of increasing metal tolerance and phytoremediation potential using genetic transformation of plants

Avoidance and reduction of soil contamination with heavy metals is one of the most serious global challenges. Nowadays, science offers us new opportunities of utilizing plants to extract toxic elements from the soil by means of phytoremediation. Plant abilities to uptake, translocate, and transform heavy metals, as well as to limit their toxicity, may be significantly enhanced via genetic engineering. This paper provides a comprehensive review of recent strategies aimed at the improvement of plant phytoremediation potential using plant transformation and employing current achievements in nuclear and cytoplasmic genome transformation. Strategies for obtaining plants suitable for effective soil clean-up and tolerant to excessive concentrations of heavy metals are critically assessed. Promising directions in genetic manipulations, such as gene silencing and cis- and intragenesis, are also discussed. Moreover, the ways of overcoming disadvantages of phytoremediation using genetic transformation approachare proposed. The knowledge gathered here could be useful for designing new research aimed at biotechnological improvement of phytoremediation efficiency.

Protoplast culture utilization in studies on legume crops.

Abstract Plant protoplasts are single cells that have had their cell walls removed by enzymatic digestion. Under appropriate in vitro culture conditions protoplasts rebuilt a new wall and then divide to form cell colonies, from which plantlets can develop. Legume species (Fabaceae) have significantly reduced genetic variability, probably due to their long history of inbreeding, and exhibit relatively strong recalcitrance to in vitro manipulations. Unique properties of protoplasts enable their exploitation in genetic enhancement of crops, involving creation of novel germplasm through direct transformation or somatic hybridization techniques. For these reasons, utilization of protoplast technology for legume improvement focuses on elaboration of efficient plant regeneration protocols, which lay the foundations for more complex research. Progress in the introduction of such technology into legume breeding is still somewhat limited, but recent achievements are strongly encouraging. Successful applications of somatic hybridization and transformation via direct DNA uptake have been already described for several genera, e.g. Medicago or Phaseolus. Isolated legume protoplasts also provide a valuable model in a range of fundamental and experimental studies, involving cell structure and behavior. In this article particularly interesting reports relevant to trends in applications of legume protoplasts are reviewed.

Explant-dependent receptivity to isolation and a cell-wall resynthesis in protoplast culture of recalcitrant yellow lupin.

Cell-wall resynthesis was studied in protoplast culture of yellow lupin (Lupinus luteus L.). We optimized protoplast isolation and found that explants excised from young seedling were more suitable sources of protoplasts, in contrast to callus tissue. Incubation in 2% cellulase R-10, 1% pectinase and 0.5% macerozyme solution for 3h effectively released protoplasts from majority of tested explants. Furthermore, we determined the optimal developmental age of explants which was 4, 21, 25 and 35 days for hypocotyls, cotyledons, in-vitro leaf mesophyll and ex-vitro leaf mesophyll, respectively. Explant type, culture medium and genotype influenced both a rate and a pattern of the cell wall regeneration. After 10 days of culture, the number of regenerated cells reached 44%-59% in hypocotyl, 84%-91% in cotyledonary, and 31%-42% in mesophyll protoplasts. Our results show that the earlier wall regeneration begins, the wall surface will be more incomplete. We suggest that unbalanced and inefficient cell-wall resynthesis likely contributes to recalcitrance of yellow lupin to manipulations in protoplast technology.

Evaluation of the protective role of exogenous growth regulators against Ni toxicity in woody shrub Daphne jasminea

Main conclusionThe results provide a significant verification of the activity of exogenously applied phytohormones: gibberellic acid, jasmonic acid, and brassinolide in the modulation of the plant’s response to nickel treatment.AbstractThe study investigated nickel accumulation and its toxicity to Daphne jasminea shoots cultured in vitro with or without exogenous supplementation with phytohormones: gibberellic acid (GA3), jasmonic acid (JA), and brassinolide (BL). The aim was to verify the modulatory effect of exogenous plant growth regulators (PGRs) on plant reaction to Ni excess. The combined action of Ni and PGRs was evaluated at the anatomical, ultrastructural, and biochemical levels. Nickel toxicity was manifested in decreased biomass accretion and growth tolerance index (83–53.6%), attributed to enhanced synthesis of growth inhibitors, mainly abscisic acid. As a defence reaction, endogenous gibberellins accumulated. Exogenous GA3 ameliorated the plant reaction to Ni stress, inducing proliferation and growth rate. Ni tolerance in the presence of GA3 was attributed to peroxisomal reactions that stimulated the synthesis of endogenous JA. In contrast, the application of BL caused enhanced Ni accumulation. Plants suffered from pronounced stress due to massive oxidation. The defence strategy of plants subjected to Ni and BL involved cell wall rearrangements. Exogenous JA stimulated the synthesis of active auxins and salicylic acid, contributing to enhanced mitotic activity within explants. However, JA disturbed the integrity of chloroplasts and lamellar compartments. Our study revealed that an action of exogenous PGRs may either enhance tolerance to Ni or increase metal toxicity in D. jasminea. Particularly in in vitro culture, where explants are subjected to external phytohormonal stimuli, the combined effects of supplemental PGRs may enhance stress and substantially affect plant development. Our results provide a significant verification of exogenous PGRs activity in the modulation of plant response to nickel.

Aspects of Co-tolerance Towards Salt and Heavy Metal Stresses in Halophytic Plant Species

In this chapter we were focused on physiological adaptations related to co-tolerance of plants towards salt and trace metal or metalloid stresses. Numerous halophytes, well adapted to grow in saline conditions, are concurrently able to accumulate elevated quantity of some trace elements, such as zinc, nickel, cadmium, lead or arsenic. The mechanisms underlying the tolerance to both, heavy metal or metalloid and salt toxicity level, include mainly typical defence reactions to oxidative stress and rearrangements in mineral status of particular organs which alleviate the negative consequences of stress in co-tolerant taxa. We discuss this unique feature on several examples of halophyte species tolerant to excessive amounts of trace elements, showing mechanisms which determine plant defence under intensive abiotic stress of that kind. We also discuss on the role of mineral status and ion homeostasis in developing the tolerant response on the phenotype level and compare mineral homeostasis between metal-tolerant halophytic and glycophytic species, sensitive to increased salinity.

Establishment of an in vitro culture of Pelargonium × domesticum cultivars characterized by different growth requirements

Experiments were carried out to develop micropropagation protocols for cultivars of hybrid origin which have been not cultivated via tissue culture. Proliferating cultures of Pelargonium × domesticum “Tip Top Duet” and “Black Knight” were obtained even if initially the number of excised aseptic nodal pieces was considerably reduced due to contamination with endogenic bacteria. The supplementation of a maintenance medium with either 100 or 200 mg/l peptone proved beneficial. The best propagation coefficient, exceeding 82 adventitious shoots from one initial microcutting, was obtained on a modified MS medium with an addition of 200 mg/l peptone and 0.5 mg/l adenine. The regenerated shoots readily developed new, anatomically properly formed leaves. In the plant material studied, the leaf epidermis produced glandular trichomata which were similar in structure to those observed in a standard cultivar.