Bryophytes: how to conquer an alien planet and live happily (ever after)

There are many push and pull factors that commonly drive individuals to leave their homeland. For example, escaping competition and occupying a novel habitat undoubtedly offer the advantage of new opportunities to pilgrims, but the absence of unfavorable biotic interactions can be counterbalanced by other antagonistic abiotic forces. After all, conquering an alien planet is not now nor ever was an easy task. We cannot know how many attempts and failures have punctuated the journey that led ancestral, photosynthetic organisms to leave the aquatic world and successfully establish on dry land. However, some traits developed by the ancestors of modern bryophytes that allowed them to adapt their life cycle to such a different habitat and persist there, have been undoubtedly identified

Tools for in vitro propagation/synchronization of the liverwort Marchantia polymorpha and application of a validated HPLC-ESI-MS-MS method for glutathione and phytochelatin analysis

Bryophytes, due to their poikilohydric nature and peculiar traits, are useful and versatile organisms for studies on metal accumulation and detoxification in plants. Among bryophytes, the liverwort Marchantia polymorpha is an excellent candidate as a model organism, having a key role in plant evolutionary history. In particular, M. polymorpha axenic cultivation of gametophytes offers several advantages, such as fast growth, easy propagation and high efficiency of crossing. Thus, the main purpose of this work was to promote and validate experimental procedures useful in the establishment of a standardized set-up of M. polymorpha gametophytes, as well as to study cadmium detoxification processes in terms of thiol-peptide production, detection and characterisation by HPLC-mass spectrometry. The results show how variations in the composition of the Murashige and Skoog medium impact the growth rate or development of this liverwort, and what levels of glutathione and phytochelatins are produced by gametophytes to counteract cadmium stress

Phosphorus and metal removal combined with lipid production by the green microalga Desmodesmus sp.: An integrated approach

This work focused on the potential of Desmodesmus sp. to be employed for wastewater 15 bioremediation and biodiesel production. The green microalga was grown in a culture medium with a phosphorus (P) content of 4.55 mg L-1 16 simulating an industrial effluent; it was also exposed to a bimetal solution of copper (Cu) and nickel (Ni) for 2 days. P removal was between 94 and 100%. After 2 days of exposure to metals, 94% of Cu and 85% of Ni were removed by Desmodesmus sp. Adsorption tests showed that the green microalga was able to remove up to 90% of Cu and 43% of Ni in less than 30 minutes. The presence of metals decreased the lipid yield, but biodiesel quality from the biomass obtained from metal exposed samples was higher than that grown without metals. This result revealed that this technology could offer a new alternative solution to environmental pollution and carbon-neutral fuel generation

Response of barley plants to Fe deficiency and Cd contamination as affected by S starvation

Both Fe deficiency and Cd exposure induce rapid changes in the S nutritional requirement of plants. The aim of this work was to characterize the strategies adopted by plants to cope with both Fe deficiency (release of phytosiderophores) and Cd contamination [production of glutathione (GSH) and phytochelatins] when grown under conditions of limited S supply. Experiments were performed in hydroponics, using barley plants grown under S sufficiency (1.2mM sulphate) and S deficiency (0mM sulphate), with or without Fe III-EDTA at 0.08mM for 11d and subsequently exposed to 0.05mM Cd for 24h or 72h. In S-sufficient plants, Fe deficiency enhanced both root and shoot Cd concentrations and increased GSH and phytochelatin levels. In S-deficient plants, Fe starvation caused a slight increase in Cd concentration, but this change was accompanied neither by an increase in GSH nor by an accumulation of phytochelatins. Release of phytosiderophores, only detectable in Fe-deficient plants, was strongly decreased by S deficiency and further reduced after Cd treatment. In roots Cd exposure increased the expression of the high affinity sulphate transporter gene (HvST1) regardless of the S supply, and the expression of the Fe deficiency-responsive genes, HvYS1 and HvIDS2, irrespective of Fe supply. In conclusion, adequate S availability is necessary to cope with Fe deficiency and Cd toxicity in barley plants. Moreover, it appears that in Fe-deficient plants grown in the presence of Cd with limited S supply, sulphur may be preferentially employed in the pathway for biosynthesis of phytosiderophores, rather than for phytochelatin production

Photosynthetic traits and biochemical responses in strawberry (Fragaria × ananassa duch.) leaves supplemented with led lights

Selected light wavebands promote plant development and/or the biosynthesis of targeted metabolites. This work offers new insights on the effects of red (R), green (G), blue (B), and white (W – R:G:B; 1:1:1) LED light supplementation on physiochemical traits of strawberry leaves. Gas exchange and chlorophyll fluorescence parameters, photosynthetic pigments, and superoxide anion (•O2–) content were analysed in plants grown for 1 (T1) and 17 (T17) d with light supplementations. At T1, light supplementations resulted in the enhancement of the de-epoxidation state of xanthophylls and nonphotochemical quenching, but no changes were observed in maximal photosynthetic rate (PNmax), irrespective of light spectra. At T17, xanthophyll contents remained higher only in R-supplemented plants. Overall, W light resulted in higher photosynthesis, whilst R and B light depressed PNmax values and promoted•O2 – formation at T17. G light did not induce variations in photosynthetic traits nor induced oxidative stress at both T1 and T17

Supplemental red LED light promotes plant productivity, “photomodulate” fruit quality and increases Botrytis cinerea tolerance in strawberry

This work provides new evidences on the effect of pre-harvest red (R), green (G), blue (B), and white (W - R:G:B; 1:1:1) LED light supplementation on production, nutraceutical quality and Botrytis cinerea control of harvested strawberry fruit. Yield, fruit color, firmness, soluble solid content, titratable acidity, primary and specialized metabolites, expression of targeted genes and mold development were analyzed in fruit from light-supplemented plants, starting from the strawberry flowering, radiating 250 mu mol m-2 s-1 of light for five hours per day (from 11:00 to 16:00 h), until the fruit harvest. Briefly, R light induced the highest productivity and targeted antho-cyanin accumulation, whilst B and G lights increased the accumulation of primary and secondary metabolites especially belonging to ellagitannin and proanthocyanidin classes. R light also promoted pathogen tolerance in fruit by the upregulation of genes involved in cell wall development (F x aPE41), inhibition of fungus poly-galacturonases (F x aPGIP1) and the degradation of B. cinerea beta-glucans (F x aBG2-1). Our dataset highlights the possibility to use red LED light to increase fruit yield, "photomodulate" strawberry fruit quality and increase B. cinerea tolerance. These results can be useful in terms of future reduction of agrochemical inputs through the use of R light, enhancing, at the same time, fruit production and quality. Finally, further analyses might clarify the effect of pre-harvest supplemental G light on postharvest fruit quality

Glutathione Transferase from Trichoderma virens Enhances Cadmium Tolerance without Enhancing Its Accumulation in Transgenic Nicotiana tabacum

BACKGROUND: Cadmium (Cd) is a major heavy metal pollutant which is highly toxic to plants and animals. Vast agricultural areas worldwide are contaminated with Cd. Plants take up Cd and through the food chain it reaches humans and causes toxicity. It is ideal to develop plants tolerant to Cd, without enhanced accumulation in the edible parts for human consumption. Glutathione transferases (GST) are a family of multifunctional enzymes known to have important roles in combating oxidative stresses induced by various heavy metals including Cd. Some GSTs are also known to function as glutathione peroxidases. Overexpression/heterologous expression of GSTs is expected to result in plants tolerant to heavy metals such as Cd. RESULTS: Here, we report cloning of a glutathione transferase gene from Trichoderma virens, a biocontrol fungus and introducing it into Nicotiana tabacum plants by Agrobacterium-mediated gene transfer. Transgenic nature of the plants was confirmed by Southern blot hybridization and expression by reverse transcription PCR. Transgene (TvGST) showed single gene Mendelian inheritance. When transgenic plants expressing TvGST gene were exposed to different concentrations of Cd, they were found to be more tolerant compared to wild type plants, with transgenic plants showing lower levels of lipid peroxidation. Levels of different antioxidant enzymes such as glutathione transferase, superoxide dismutase, ascorbate peroxidase, guiacol peroxidase and catalase showed enhanced levels in transgenic plants expressing TvGST compared to control plants, when exposed to Cd. Cadmium accumulation in the plant biomass in transgenic plants were similar or lower than wild-type plants. CONCLUSION: The results of the present study suggest that transgenic tobacco plants expressing a Trichoderma virens GST are more tolerant to Cd, without enhancing its accumulation in the plant biomass. It should be possible to extend the present results to crop plants for developing Cd tolerance and in limiting Cd availability in the food chain