Differential Response of Two Tomato Genotypes, Wild Type cv. Ailsa Craig and Its ABA-Deficient Mutant flacca to Short-Termed Drought Cycles.

Two tomato genotypes with constitutively different ABA level, flacca mutant and wild type of Ailsa Craig cv. (WT), were subjected to three repeated drought cycles, with the aim to reveal the role of the abscisic acid (ABA) threshold in developing drought tolerance. Differential responses to drought of two genotypes were obtained: more pronounced stomatal closure, ABA biosynthesis and proline accumulation in WT compared to the mutant were compensated by dry weight accumulation accompanied by transient redox disbalance in flacca. Fourier-transform infrared (FTIR) spectra analysis of isolated cell wall material and morphological parameter measurements on tomato leaves indicated changes in dry weight accumulation and carbon re-allocation to cell wall constituents in flacca, but not in WT. A higher proportion of cellulose, pectin and lignin in isolated cell walls from flacca leaves further increased with repeated drought cycles. Different ABA-dependent stomatal closure between drought cycles implies that acquisition of stomatal sensitivity may be a part of stress memory mechanism developed under given conditions. The regulatory role of ABA in the cell wall restructuring and growth regulation under low leaf potential was discussed with emphasis on the beneficial effects of drought priming in developing differential defense strategies against drought.

Biomonitoring of Urban Pollution Using Silicon-Accumulating Species, Phyllostachys aureosulcata 'Aureocaulis'.

We investigated metal accumulation in bamboo leaves during three seasons at three urban locations differing in pollution levels. The higher content of Cu, Pb, and Zn in the leaves was in correlation with the highest bioavailable content of these elements in the soil at the most polluted location. The content of leaf trace elements was higher in summer and autumn compared to spring. Scanning electron microscopy with energy dispersive X-ray spectroscopy showed that Si accumulation in bamboo leaves was the highest in epidermis and vascular tissue, and was co-localized with trace metals. Analysis of phytoliths showed co-deposition of Al, C, and Si, implying the involvement of Si in metal detoxification. Compared to a common urban tree, linden, bamboo showed better capacity to maintain cellular redox homeostasis under deteriorated environmental conditions. The results suggest that bamboo can be efficiently used for biomonitoring of air and soil metal pollution and remediation in urban areas.