Development of grapevine plants under hydroponic copper-enriched solutions induced morpho-histological, biochemical and cytogenetic changes

Nucleolar actions in plant development and stress responses

The nucleolus is conventionally acknowledged for its role in ribosomal RNA (rRNA) synthesis and ribosome biogenesis. Recent research has revealed its multifaceted involvement in plant biology, encompassing regulation of the cell cycle, development, and responses to environmental stresses. This comprehensive review explores the diverse roles of the nucleolus in plant growth and responses to environmental stresses. The introduction delves into its traditional functions in rRNA synthesis and potential participation in nuclear liquid-liquid phase separation. By examining the multifaceted roles of nucleolar proteins in plant development, we highlight the impacts of various nucleolar mutants on growth, development, and embryogenesis. Additionally, we reviewed the involvement of nucleoli in responses to abiotic and biotic stresses. Under abiotic stress conditions, the nucleolar structure undergoes morphological changes. In the context of biotic stress, the nucleolus emerges as a common target for effectors of pathogens for manipulation of host immunity to enhance pathogenicity. The detailed exploration of how pathogens interact with nucleoli and manipulate host responses provides valuable insights into plant stress responses as well as plant growth and development. Understanding these processes may pave the way for promising strategies to enhance crop resilience and mitigate the impact of biotic and abiotic stresses in agricultural systems.

Selection of Reference Genes and HSP17.9A Expression Profiling in Heat-Stressed Grapevine Varieties

BACKGROUND

"Touriga Franca" (TF) and "Touriga Nacional" (TN) are grapevine varieties cultivated in the 'Douro Superior' subregion (Northern Portugal) that experience stressful environmental conditions during the summer.

OBJECTIVES

Aiming to profile the expression of stress-responsive genes by quantitative real-time PCR (qPCR) in TF and TN plants growing naturally, three candidate reference genes were first tested under controlled conditions.

METHODS

To simulate a summer's day, TF and TN in vitro plants were exposed to 32 °C-3 h (heat acclimation) and 42 °C-1 h (severe heat stress, HS) followed by two recovery periods (32 °C-3 h and 24 °C-24 h). Leaf samples were collected at the end of each phase. Control plants were kept at 24 °C.

RESULTS

Among the candidate reference genes, the UBC and VAG pair showed the highest stability. The suitability of these genes for qPCR was validated by heat shock protein 17.9A (HSP17.9A) gene profiling. The HSP17.9A expression was up-regulated in both varieties and all experimental phases except in TF control plants. TN showed the highest HSP17.9A relative expression ratio after severe HS.

CONCLUSIONS

TN responded faster than TF to the induced heat shocks. The UBC, VAG, and HSP17.9A genes revealed to be suitable for further qPCR assays in TF and TN grapevine varieties.

Combination of Iron and Zinc Enhanced the Root Cell Division, Mitotic Regularity and Nucleolar Activity of Hexaploid Triticale

Hexaploid triticale results from crosses between durum wheat and rye. Despite its high agronomic potential, triticale is mainly used for livestock feed. Triticale surpasses their parental species in adaptability and tolerance to abiotic and biotic stresses, being able to grow in acidic soils where a high amount of iron (Fe) and zinc (Zn) is typical. On the other hand, high amounts of these essential trace elements can be cytotoxic to bread wheat. The cytotoxicity induced by seed priming with a high concentration of Fe and Zn impaired root cell division and induced nucleolar changes in bread wheat. Such cytogenetic approaches were expedited and successfully determined cytotoxic and suited micronutrient dosages for wheat nutripriming. With this study, we intended to analyse the hexaploid triticale cv 'Douro' root mitotic cell cycle and nucleolar activity after seed priming performed with aqueous solutions of iron (Fe) and/or zinc (Zn), containing a concentration that was previously considered cytotoxic, to bread wheat and to infer the higher tolerance of triticale to these treatments. The overall cytogenetic data allowed us to conclude that the Fe + Zn treatment enhanced the root mitotic index (MI), mitosis regularity and nucleolar activity of 'Douro' relative to the control and the individual treatments performed with Fe or Zn alone. The Fe + Zn treatment might suit triticale biofortification through seed priming.

Recent advances on botanical biosynthesis of nanoparticles for catalytic, water treatment and agricultural applications: A review

Green synthesis of nanoparticles using plant extracts minimizes the usage of toxic chemicals or energy. Here, we concentrate on the green synthesis of nanoparticles using natural compounds from plant extracts and their applications in catalysis, water treatment and agriculture. Polyphenols, flavonoid, rutin, quercetin, myricetin, kaempferol, coumarin, and gallic acid in the plant extracts engage in the reduction and stabilization of green nanoparticles. Ten types of nanoparticles involving Ag, Au, Cu, Pt, CuO, ZnO, MgO, TiO₂, Fe₃O₄, and ZrO₂ with emphasis on their formation mechanism are illuminated. We find that green nanoparticles serve as excellent, and recyclable catalysts for reduction of nitrophenols and synthesis of organic compounds with high yields of 83-100% and at least 5 recycles. Many emerging pollutants such as synthetic dyes, antibiotics, heavy metal and oils are effectively mitigated (90-100%) using green nanoparticles. In agriculture, green nanoparticles efficiently immobilize toxic compounds in soil. They are also sufficient nanopesticides to kill harmful larvae, and nanoinsecticides against dangerous vectors of pathogens. As potential nanofertilizers and nanoagrochemicals, green nanoparticles will open a revolution in green agriculture for sustainable development.

Modeling Alleviative Effects of Ca, Mg, and K on Cu-Induced Oxidative Stress in Grapevine Roots Grown Hydroponically

The aim of this study was to determine the pattern of alleviation effects of calcium (Ca), magnesium (Mg), and potassium (K) on copper (Cu)-induced oxidative toxicity in grapevine roots. Root growth, Cu and cation accumulation, reactive oxygen species (ROS) production, and antioxidant activities were examined in grapevine roots grown in nutrient solutions. The experimental setting was divided into three sets; each set contained a check (Hoagland solution only) and four treatments of simultaneous exposure to 15 μM Cu with four cation levels (i.e., Ca set: 0.5, 2.5, 5, and 10 mM Ca; Mg set: 0.2, 2, 4, and 8 mM Mg; K set: 0.6, 2.4, 4.8, and 9.6 mM K). A damage assessment model (DAM)-based approach was then developed to construct the dose-effect relationship between cation levels and the alleviation effects on Cu-induced oxidative stress. Model parameterization was performed by fitting the model to the experimental data using a nonlinear regression estimation. All data were analyzed by a one-way analysis of variance (ANOVA), followed by multiple comparisons using the least significant difference (LSD) test. The results showed that significant inhibitory effects on the elongation of roots occurred in grapevine roots treated with 15 μM Cu. The addition of Ca and Mg significantly mitigated phytotoxicity in root growth, whereas no significant effect of K treatment on root growth was found. With respect to oxidative stress, ROS and malondialdehyde (MDA) contents, as well as antioxidant (superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX)) activities, were stimulated in the roots after exposure to 15 μM Cu for three days. Moreover, H₂O₂ levels decreased significantly as Ca, Mg, and K concentrations increased, indicating that the coexistence of these cations effectively alleviated Cu-induced oxidative stress; however, alleviative effects were not observed in the assessment of the MDA content and antioxidant enzyme activities. Based on the DAM, an exponential decay equation was developed and successfully applied to characterize the alleviative effects of Ca, Mg, and K on the H₂O₂ content induced by Cu in the roots. In addition, compared with Mg and K, Ca was the most effective cation in the alleviation of Cu-induced ROS. Based on the results, it could be concluded that Cu inhibited root growth and Ca and Mg absorption in grapevines, and stimulated the production of ROS, lipid peroxidation, and antioxidant enzymes. Furthermore, the alleviation effects of cations on Cu-induced ROS were well described by the DAM-based approach developed in the present study.

Regenerative ability of grape cuttings under the influence of yeast suspension treatment

The paper presents the growing experiment results on activating the regenerative ability of Moldova table variety grape cuttings by processing pressed baking yeast suspension. The present circumstance became the basis for conducting special studies to check cutting response to the treatment with baking yeast suspension, with the identification of drug optimal concentration. In spring, the two-eyed cuttings were completely soaked for 24 hours in water, and then they were placed with the basal ends in yeast suspension at various concentrations for the same time. Moreover, these yeast suspension concentrations were tested both in pure form and in combination with 3% sucrose. As a result of the conducted studies, it was revealed that pressed baking yeast suspension at certain concentration can have an activating effect on regenerative ability of grape cuttings. The use of yeast suspension together with sucrose solution increases their physiological activity. It was found that cuttings basal end soaking in yeast suspension at concentrations of 10-20 g/l, together with sucrose, contributed to rooting increased by 20-30%, the proportion of cuttings with three roots or more – by 22.5-30.0%, the number of roots by 13.5–16.2%. The best option was with a yeast suspension concentration of 20 g/l.