DNA Methylation—An Epigenetic Mark in Mutagen-Treated Brachypodium distachyon Cells

The chromatin structure is significantly influenced by some epigenetic modifications including DNA methylation. The nuclear organization plays an essential role in the cell response to external stresses including mutagens. We present an analysis of the correlation between epigenetic modifications and the instability of the Brachypodium distachyon genome, which are observed as micronuclei, following maleic hydrazide (MH) and nitroso-N-methylurea (MNU) treatments. We compared the level of DNA methylation in the control (untreated) and mutagen-treated B. distachyon nuclei. An immunostaining method using specific antibodies against modified DNA anti-5-methylcytosine was used for the evaluation of DNA methylation in a single nucleus and micronucleus. Interestingly, we showed an alteration of DNA methylation in cells after mutagenic treatments. The results indicate that DNA methylation might be involved in the response of the B. distachyon genome to mutagenic treatments. This demonstrates that analyses of the epigenetic modifications should be integrated into current plant genetic toxicology in order to explain the mechanisms of DNA damage and repair in plants.

Molecular mechanism underlying the effect of maleic hydrazide treatment on starch accumulation in S. polyrrhiza 7498 fronds

Background Duckweed is considered a promising feedstock for bioethanol production due to its high biomass and starch production. The starch content can be promoted by plant growth regulators after the vegetative reproduction being inhibited. Maleic hydrazide (MH) has been reported to inhibit plant growth, meantime to increase biomass and starch content in some plants. However, the molecular explanation on the mechanism of MH action is still unclear. Results To know the effect and action mode of MH on the growth and starch accumulation in Spirodela polyrrhiza 7498, the plants were treated with different concentrations of MH. Our results showed a substantial inhibition of the growth in both fronds and roots, and increase in starch contents of plants after MH treatment. And with 75 µg/mL MH treatment and on the 8th day of the experiment, starch content was the highest, about 40 mg/g fresh weight, which is about 20-fold higher than the control. The I2-KI staining and TEM results confirmed that 75 µg/mL MH-treated fronds possessed more starch and big starch granules than that of the control. No significant difference for both in the photosynthetic pigment content and the chlorophyll fluorescence parameters of PII was found. Differentially expressed transcripts were analyzed in S. polyrrhiza 7498 after 75 µg/mL MH treatment. The results showed that the expression of some genes related to auxin response reaction was down-regulated; while, expression of some genes involved in carbon fixation, C4 pathway of photosynthesis, starch biosynthesis and ABA signal transduction pathway was up-regulated. Conclusion The results provide novel insights into the underlying mechanisms of growth inhibition and starch accumulation by MH treatment, and provide a selective way for the improvement of starch production in duckweed.

THE KINETICS OF SELECTIVE HYDRAZINOLYSIS OF MALEIC ACID ON THE ACID CATALYST

For the first time, kinetics and the mechanism of the reaction of hydrazinolysis of maleic acid in the presence of cation exchanger resin KU-2-8 in H-form have been studied. The experiments were carried out in a static system in a thermostat glass reactor. It was found that cation exchanger shows high catalytic activity in the studied process - maleic acid conversion was 93%, and maleic hydrazide yield was 90%. The conversion selectivity of maleic acid to maleic hydrazide was 97,8%. The reaction rate was determined from the accumulation of maleic hydrazide. The apparent reaction rate constant (k) was calculated from the second-order reaction rate equation. The effect of initial concentrations of maleic acid and hydrazine hydrate, the temperature on the reaction rate was studied. The first order of maleic acid and hydrazine hydrate is determined. Activation energy of the process found from the Arrhenius dependence is 32,1 kJ/mol. On the basis of kinetic and IR spectroscopic methods, a probable reaction mechanism involving polymer-bound hydrogen ions is proposed.

A Tool Derived from the Vicia faba Micronucleus Assay, to Assess Genotoxicity, Cytotoxicity or Biostimulation of Novel Compounds Used in Agriculture

The increased use of biostimulants in conventional agriculture and organic farming requires the implementation of rapid tests to determine their effectiveness in enhancing plant growth and protection against abiotic stresses. However, their innocuity to plant health has rarely been demonstrated. We used the Vicia faba Micronucleus Assay, as described by the standard AFNOR EN ISO 29200(2020-05) to reveal biostimulant, genotoxic and cytotoxic effects of four commercialized wood-based products by comparing mitotic indices and micronucleus frequencies with respect to the controls. Neither genotoxicity, as measured by micronucleus frequency (MN), nor cytotoxicity, assessed by Mitotic index counts, was observed. Additionally, one of these stimulants (BHS®) conferred protective effects against contaminants (maleic hydrazide or lead nitrate). We describe that plotting micronuclei frequency against mitotic indices allows discrimination between cytotoxic/genotoxic effects from growth levels. Vicia faba experiments were successfully transposed to other agronomical important crops such as corn and sunflower. This technique can be valuable to industrials, to assess growth, potential cytoxicity and genotoxicity effects of any new biostimulant or organic.

Intelligent analysis of maleic hydrazide using a simple electrochemical sensor coupled with machine learning

A simple intelligent electrochemical sensing platform based on a low-cost disposable laser-induced porous graphene flexible electrode for maleic hydrazide coupled with machine learning was successfully designed.

Nipping - A Simple Strategy to Boost The Yield - Review

Nipping is an important practice that removes the apical dominance and promotes the lateral branches which in turn improves the yield of crops. It plays a vital role for better maintenance of source and sink relationship and for ameliorating the productivity. Nipping can be done in two ways either by clipping manually or by spraying growth retardants such as mepiquat chloride, chlormequat chloride and maleic hydrazide. In this review, the influence of nipping on the growth and yield of various crops has been discussed.

The Herbicidal Potential of Different Pelargonic Acid Products and Essential Oils against Several Important Weed Species

There is growing consideration among farmers and researchers regarding the development of natural herbicides providing sufficient levels of weed control. The aim of the present study was to compare the efficacy of four different pelargonic acid products, three essential oils and two natural products’ mixtures against L. rigidum Gaud., A. sterilis L. and G. aparine L. Regarding grass weeds, it was noticed at 7 days after treatment that PA3 treatment (pelargonic acid 3.102% w/v + maleic hydrazide 0.459% w/v) was the least efficient treatment against L. rigidum and A. sterilis. The mixture of lemongrass oil and pelargonic acid resulted in 77% lower dry weight for L. rigidum in comparison to the control. Biomass reduction reached the level of 90% as compared to the control in the case of manuka oil and the efficacy of manuka oil and pelargonic acid mixture was similar. For sterile oat, weed biomass was recorded between 31% and 33% of the control for lemongrass oil, pine oil, PA1 (pelargonic acid 18.67% + maleic hydrazide 3%) and PA4 (pelargonic acid 18.67%) treatments. In addition, the mixture of manuka oil and pelargonic acid reduced weed biomass by 96% as compared to the control. Regarding the broadleaf species G. aparine, PA4 and PA1 treatments provided a 96–97% dry weight reduction compared to the corresponding value recorded for the untreated plants. PA2 (pelargonic acid 50% w/v) treatment and the mixture of manuka oil and pelargonic acid completely eliminated cleaver plants. The observations made for weed dry weight on the species level were similar to those made regarding plant height values recorded for each species. Further research is needed to study more natural substances and optimize the use of natural herbicides as well as natural herbicides’ mixtures in weed management strategies under different soil and climatic conditions.