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The taxonomy of genera Anabaena and Nostoc is very controversial. They are typically paraphyletic within phylogenetic trees and show similar morphological characters. The present study aimed to determine the taxonomic relationships among Anabaena and Nostoc strains of the Mosonmagyarovar Algal Culture Collection (MACC) using 16S rRNA and rbcLX gene sequences. We concluded on the basis of the number of unsuccessful amplifications that more of the examined MACC Nostoc cultures are axenic than the Anabaena cultures. In agreement with previous studies we noticed that the applied phylogenetic algorithms gave congruent results in phylogenetic analyses. However, the genus Nostoc clearly was found not monophyletic in the present study and this finding differed from many of the previous studies. Molecular results contradicted the previous morphology-based classification of some MACC cyanobacteria strains, therefore polyphasic taxonomic approaches are required for the reliable identification of cyanobacterial species. Some strains seemed to be identical based on the alignment of 16S rRNA or rbcLX sequences.

Efficient Agrobacterium-mediated transformation was established via sonication of embryonic shoot apical meristems (ESAMs) of Dierama erectum Hilliard. Effects of explant types, co-cultivation time, acetosyringone concentration, Agrobacterium concentration and different gene delivery methods were evaluated for higher efficiency of genetic transformation in D. erectum. An explant type (ESAMs), concentration of Agrobacterium inoculum (OD600 of 1.6) and acetosyringone (50 mg L− 1), and co-cultivation duration (3 days) were optimized for efficient genetic transformation of D. erectum. The transformation efficiency varied with explant types (from 0 to 60%), concentrations of bacteria (10 to 55%) and acetosyringone (50 to 90%) and period of co-cultivation (30 to 70%). The transformation efficiency was best with ESAMs explants compared with callus clusters. The gene delivery method via sonication-assisted Agrobacterium-mediated transformation (SAAT) provided higher transformation efficiency (40%) GUS expression compared with agrobacterial monolayer and agrobacterial suspension which gave less than 5% transformation efficiency. The putative transgenic plants which histochemically expressed GUS, were confirmed further with PCR and 35.3% of the plants were GUS positive. Stable integration of the transgene was not demonstrated hence the GUS expression observed was regarded as transient. This newly developed transformation system may facilitate improvement of D. erectum characteristics and other related geophytes.

Lipid biosynthesis in microalgae can be stimulated by cultivation in low nitrogen medium. MACC-401 was isolated from the soil surface in Tres Marias (MG-Brazil). The strain shows the morphological characteristics of the Scenedesmaceae green algae. The daily biomass and lipid production of MACC-401 is remarkable, 0.36 g L−1 and 110 mg L−1, respectively. Exploration of the genetic background of this promising strain not only allows the utilization of this species for industrial-scale lipid production, but also provides genetic targets to select lipid-producing strains from microalgae collections. We conducted physiological experiments by cultivating MACC-401 in complete and N-limited media and performed genome sequencing as well as transcriptome analysis. The estimated nuclear genome size of MACC-401 is 99.503 Mbp and the chloroplast genome is 0.15 Mbp. The phylogenetic analysis confirmed that the MACC-401 belongs to the Scenedesmaceae family, and represents a genetically distinct accession in this family. A basic comparative transcriptome analysis resulted in the identification of N-starvation responsive genes, which could serve as markers to monitor the onset of lipid accumulation in algal cultures.

Herein we report the synthesis of new probes for photoaffinity labeling with the aim of receptor identification and mode of action elucidation of 3,4,5-trimethylfuran-2(5H)-one (TMB), recently identified in the smoke of burning vegetation as an efficient seed germination inhibitor. These photoaffinity probes consist of an ethynyl group that acts as a tag for introduction of an optional detectable marker unit by an appropriate chemoselective ligation method after the photo-cross-linking operation.

The objective of this study was to develop a simple and efficient system for the genetic transformation of cucumber (Cucumis sativus L.). This study investigated the factors influencing the efficiency of gene transfer by microinjection of the shoot apical meristem (SAM) with Agrobacterium shooter strain. The SAM microinjected with Agrobacterium cells containing binary plasmid was incubated in co-cultivation medium without plant growth regulators (PGRs) for 2 days in the dark and subsequently transferred to solid bacterial elimination shoot regeneration medium containing MS salts plus 20 g l− 1 glucose, 8 g l− 1 agar and 300 mg l− 1 cefotaxime. Developed transgenic shoots were screened in selection medium containing the antibiotic kanamycin (Km). The efficiency of gene transfer using various germination media and infection conditions was analyzed by root growth in the presence of Km. The present investigations show that the maximum efficiency of gene transfer was sixty-five percent by Km-resistant plants. In the putative transgenic plants the presence of the transgene was confirmed by polymerase chain reaction (PCR). This transformation system was reproducible, suggesting that it could be adopted for other plant species.

Smoke plays a positive role in promoting seed germination and enhancing post-germination processes. The compound in smoke is 3-methyl-2 H -furo[2,3- c ]pyran-2-one (KAR 1 ). Recently a structurally related butenolide [3,4,5-trimethylfuran-2(5 H )-one, (trimethylbutenolide, TMB)], which inhibits germination and reduces the effect of KAR 1 , was isolated. The mechanisms of action and interaction of these karrikins are unknown. In addition, the ecological significance of fires in altering soil-smoke-chemistry and the spatial dimensions of the influence on burnt sites and neighbouring areas are undetermined. This study quantified KAR 1 and TMB residues in soils following fire and assessed the germination activity of burnt soil extracts. Soil samples from 0 to 2, 2 to 4, 4 to 6 and 6 to 8 cm depths were extracted using dichloromethane and bioassayed using Lactuca sativa L. achenes (seeds). At all soil depths, L. sativa seeds exhibited significantly greater percentage germination when treated with burnt soil extracts compared to the no-burn soil (control). The L. sativa seeds also showed significantly greater percentage germination when treated with soil extracts from the adjacent plots. Compared to the no-burn soil, higher concentrations of KAR 1 and TMB were detected in the surface layers of the burnt soils. Considerable concentrations of KAR 1 and TMB were also detected in no-burn soil indicating that sources other than fire may also generate karrikins. Findings of this study imply that post-fire increases in KAR 1 residues in the soil may influence soil seed bank stimulation of certain smoke-responsive plant communities in both burnt and adjacent non-burnt areas.

Prevention of ethylene- and shipping-induced flower abscission is necessary to maintain the quality of both cut flowers and potted plants during handling, transport and retail display. The aims of the present work were to determine the sensitivity of Plectranthus cultivars to applied ethylene, to alleviate ethylene- and shipping-induced flower abscission in intact potted plants using 1-methylcyclopropene (1-MCP), and to investigate the possible causes of dark-induced flower abscission. All cultivars were sensitive to ethylene in a concentration-dependent manner, and complete abscission occurred within 24 h with 1 and 2 μl l− 1 ethylene. Unopened buds were more sensitive to applied ethylene, and exhibited greater abscission than open flowers. Ethylene synthesis remained below detection limits at all time points under control and continuous dark conditions. Dark treatment significantly increased flower abscission in Plectranthus cultivars, and like ethylene-induced flower abscission, this could be prevented by continuous 1-MCP treatment. Gene expression of ethylene biosynthetic enzymes ACS and ACO was examined as possible causes for the accelerated flower abscission observed in plants kept in continuous darkness. Expression patterns of ACS and ACO varied between different cultivars of Plectranthus. In some cases, increased expression of ACS and ACO led to increased flower abscission. Gene expression was higher in open flowers when compared to unopened flowers suggesting a cause for the observed preferential shedding of open flowers in some cultivars. Although the cause of dark-induced abscission in Plectranthus remains elusive, it can be effectively controlled by treatment with 1-MCP.

Salicylic acid (SA), which is known as a signal molecule in the induction of defense mechanisms in plants, could be a promising compound for the reduction of stress sensitivity. The aim of the present work was to investigate the distribution of SA in young pea (Pisum sativum L.) seedlings grown from seeds soaked in 3H-labeled SA solution before sowing, and to study the physiological changes induced by this seed treatment. The most pronounced changes in SA levels occurred in the epicotyl and the seeds. Radioactivity was detected only in the bound form of SA, the majority of which was localized in the seeds, and only a very low level of radioactivity was detected in the epicotyl. SA pre-treatment increased the expression of the chorismate synthase and isochorismate synthase genes in the epicotyl. Pre-soaking the seeds in SA increased the activities of some antioxidant enzymes, namely ascorbate peroxidase (EC 1.11.1.11) and guaiacol peroxidase (EC 1.11.1.7) and the level of ortho-hydroxycinnamic acid, but decreased the level of polyamines. These results suggest that the increased level of free and bound SA detected in plants growing from seeds soaked in SA solution before sowing is the product of de novo synthesis, rather than having been taken up and mobilized by the plants.

Paraquat (Pq) inducible transporters are presumed to play a role in the resistance mechanism of horseweed and to function by carrying paraquat to a metabolically inactive compartment. The uptake and intracellular localisation of paraquat, the effect of transporter inhibitors on resistance, and paraquat-induced gene expression were studied to obtain a better understanding of the mechanism of resistance. Investigations proved that paraquat entered the cells of both resistant and susceptible biotypes, approached the maximum within the first hour in chloroplasts, and then declined in all organelle fractions. In the resistant biotype paraquat was located in the vacuoles a day after treatment. Selective transporter inhibitors blocked the sequestration of paraquat, suggesting the participation of not directly energized transporters. Four EST fragments were identified that were expressed in response to paraquat. Two of them are thought to play a role in the general stress response (Ferr2, Myb). The others exhibit a similarity to transporters (EmrE, CAT) and could conceivably be involved in the intracellular transport of paraquat and the mechanism of resistance.