Plant Growth Regulation in Cell and Tissue Culture In Vitro

Anti-inflammatory, antioxidant, and acute toxicity of Brugmansia arborea extracts from wild plants and shoots obtained by indirect organogenesis. A thermographic assay to anti-inflammatory evaluation

Inflammation is a condition that affects a large percentage of the population, rendering the search for alternative treatments urgent. Medicinal plant such as Brugmansia arborea has been employed in traditional medicine, it is used to alleviate menstrual pain, acne, promote wound healing, and ease joint pain, headaches, and other ailments. Some alkaloids (mainly atropine, scopolamine, and nor-hyoscyamine) have been described. In this paper, the in-vitro cultivation from leaf explants of B. arborea through indirect organogenesis is described. From wild plants (BA) and shoots (BAB) their extracts were prepared, and were analyzed by thin-layer chromatography and gas chromatography-mass spectrometry, identifying 18 main metabolites. Antioxidant activity was assessed with EC50 = 199.52 and 31.63 mg/mL for BA and BAB, respectively. Boths extracts showed a DL50 > 2 g/kg and is classified as non-toxic. In Acetylated and Hydrolyzed extracts, acetyl-rutin and kaempferol, respectively were identified. Anti-inflammatory activity was assayed employing carrageenan model. The ED50 values were < 158.48 mg/kg by BA, BAB, Ac-BA, and H-BA, being more active the hydrolyzed extract (ED50 = 63.09 and 64.56 mg/kg) for females and male mice. In topical TPA model, the ED50 value were < 0.47 mg/ear for BA, BAB, Ac-BA, and H-BA. Thermographic analysis is a non-invasive, cheap, effective and reproducible method to evaluate the anti-inflammatory effect of substances, since it quantifies the increase in temperature in an inflammatory process, so this technique constitutes an alternative in the search for this type of agent.

HDC1 Promotes Primary Root Elongation by Regulating Auxin and K+ Homeostasis in Response to Low-K+ Stress

Plants frequently encounter relatively low and fluctuating potassium (K+) concentrations in soil, with roots serving as primary responders to this stress. Histone modifications, such as de-/acetylation, can function as epigenetic markers of stress-inducible genes. However, the signaling network between histone modifications and low-K+ (LK) response pathways remains unclear. This study investigated the regulatory role of Histone Deacetylase Complex 1 (HDC1) in primary root growth of Arabidopsis thaliana under K+ deficiency stress. Using a hdc1-2 mutant line, we observed that HDC1 positively regulated root growth under LK conditions. Compared to wild-type (WT) plants, the hdc1-2 mutant exhibited significantly inhibited primary root growth under LK conditions, whereas HDC1-overexpression lines displayed opposite phenotypes. No significant differences were observed under HK conditions. Further analysis revealed that the inhibition of hdc1-2 on root growth was due to reduced apical meristem cell proliferation rather than cell elongation. Notably, the root growth of hdc1-2 showed reduced sensitivity compared to WT after auxin treatment under LK conditions. HDC1 may regulate root growth by affecting auxin polar transport and subsequent auxin signaling, as evidenced by the altered expression of auxin transport genes. Moreover, the organ-specific RT-qPCR analyses unraveled that HDC1 negatively regulates the expression of CBL-CIPK-K+ channel-related genes such as CBL1, CBL2, CBL3, AKT1, and TPK1, thereby establishing a molecular link between histone deacetylation, auxin signaling, and CBLs-CIPKs pathway in response to K+ deficiency.

The Role of Polyphenols in Abiotic Stress Tolerance and Their Antioxidant Properties to Scavenge Reactive Oxygen Species and Free Radicals

Plants have evolved complex mechanisms to cope with diverse abiotic stresses, with the phenylpropanoid pathway playing a central role in stress adaptation. This pathway produces an array of secondary metabolites, particularly polyphenols, which serve multiple functions in plant growth, development, regulating cellular processes, and stress responses. Recent advances in understanding the molecular mechanisms underlying phenylpropanoid metabolism have revealed complex regulatory networks involving MYB transcription factors as master regulators and their interactions with stress signaling pathways. This review summarizes our current understanding of polyphenol-mediated stress adaptations in plants, emphasizing the regulation and function of key phenylpropanoid pathway compounds. We discussed how various abiotic stresses, including heat and chilling stress, drought, salinity, light stress, UV radiation, nanoparticles stress, chemical stress, and heavy metal toxicity, modulate phenylpropanoid metabolism and trigger the accumulation of specific polyphenolic compounds. The antioxidant properties of these metabolites, including phenolic acids, flavonoids, anthocyanins, lignin, and polyphenols, and their roles in reactive oxygen species scavenging, neutralizing free radicals, membrane stabilization, and osmotic adjustment are discussed. Understanding these mechanisms and metabolic responses is crucial for developing stress-resilient crops and improving agricultural productivity under increasingly challenging environmental conditions. This review provides comprehensive insights into integrating phenylpropanoid metabolism with plant stress adaptation mechanisms, highlighting potential targets for enhancing crop stress tolerance through metabolic adjustment.

Insights on the Mesembryanthemum forsskalii phenotype and study of the effects of several exogenous plant growth regulators via plant tissue culture

BACKGROUND

Samh (Mesembryanthemum forsskalii, M. cryptanthum) belongs to Aizoaceae family and is found in northern Saudi Arabia, primarily in desert or dry shrubland habitats. M. forsskalii is characterized by several nutritional and medicinal benefits. This study aimed to explore the phenotypic features of M. forsskalii and investigate the impact of exogenous plant growth regulators (PGRs) on this species using tissue culture techniques. Different auxin (naphthalene acetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D) and indole butyric acid (IBA) in addition cytokinin (benzyl amino purine (BA), and kinetin (Ki) treatments were used.

RESULTS

The phenotypic features of M. forsskalii included being decumbent to erect, with many terete succulent branches covered by epidermal bladder cells. Plant size determines its branching type, phyllotaxis, and inflorescence. Large plants have trichotomous branching; the two lower nodes have opposite decussate leaves; and compound dichasia. The flowers are pedicellate, perigynous, and have single, tricorporate pollen grains. Additionally, M. forsskalii has taproots, which differs from what was reported for M. forsskalii in previous studies in that it has fibrous roots. A 98% response rate was seen when the receptacle was used as an initiated explant. Adding BA to the MS medium also showed a significant increase in the size of the shoot system area and the number of roots. as well as the combined Ki + 2,4-D treatment had a significant effect on the callus volume. The callus color ranged from yellowish green to brown, and compact and rooty calli (callus cells differentiated into root hairs) were observed.

CONCLUSIONS

This study investigated the phenotypic features of M. forsskalii (samh), and its micropropagation that had not been previously reported in the literature. Its branching type, phyllotaxis, and inflorescence were described. The flowers are pedicellate, and the pollen grains are single, tricorporate, and oblate. M. forsskalii has taproots, which differs from what was reported for M. cryptanthum (M. forsskalii) in previous studies in that it has fibrous roots. Therefore, the difference in the type of root may be an indication that the variety found in the Al-Jouf area is different than the previous varieties. This study was the first to examine the impact of exogenous PGR on M. forsskalii under tissue culture conditions. Based on the results of this study, the use of 2 mg/ml BA for M. forsskalii micropropagation and the combination of IBA and 2,4-D for callus induction experiments are recommended. Further molecular research on M. forsskalii is also recommended.

Optimization of Selected Minerals and a Cytokinin for In Vitro Propagation of Little-Leaf Mockorange (Philadelphus microphyllus A. Gray) Using Response Surface Methodology (RSM)

Optimizing concentrations of minerals and phytohormones is essential when culturing a new plant species. The objective of this study was to use Response Surface Methodology (RSM) to evaluate combinations of selected minerals (N, Ca, and P) along with zeatin (Zea) to obtain optimum shoot growth of little-leaf mockorange. Forty-six treatment combinations were assigned using Proc Optex in SAS software version 9.4. The concentrations of Zea tested were 0.82, 1.095, or 1.37 µM, and the minerals were 22.5, 30, or 37.5 mM N, 1.13, 1.5, or 1.875 mM Ca, and 0.31, 0.625, or 0.937 mM P. Treatment concentrations were tested for their effects on the number of axillary shoots formed, shoot length, and dry weight. The response surface analyses showed that the optimum concentrations of N, Ca, and P were 34 to 39 mM, 1.5 mM, and 0.625 mM, respectively. Medium supplemented with 1.1 µM Zea affected shoot growth positively. Comparison of mineral concentrations in medium with concentrations in full-strength Murashige and Skoog (MS) medium, suggests ½ MS medium should be appropriate to efficiently multiply little-leaf mockorange shoots efficiently, thus saving the time and money involved in creating a custom medium formulation.

Development and Applications of Somatic Embryogenesis in Grapevine (Vitis spp.)

Somatic embryogenesis (SE) provides alternative methodologies for the propagation of grapevine (Vitis spp.) cultivars, conservation of their germplasm resources, and crop improvement. In this review, the current state of knowledge regarding grapevine SE as applied to these technologies is presented, with a focus on the benefits, challenges, and limitations of this method. The paper provides a comprehensive overview of the different steps involved in the grapevine SE process, including callus induction, maintenance of embryogenic cultures, and the production of plantlets. Additionally, the review explores the development of high-health plant material through SE; the molecular and biochemical mechanisms underlying SE, including the regulation of gene expression, hormone signaling pathways, and metabolic pathways; as well as its use in crop improvement programs. The review concludes by highlighting the future directions for grapevine SE research, including the development of new and improved protocols, the integration of SE with other plant tissue culture techniques, and the application of SE for the production of elite grapevine cultivars, for the conservation of endangered grapevine species as well as for cultivars with unique traits that are valuable for breeding programs.

Optimizing Sugarcane Clonal Propagation In Vitro by Using Calcium Ammonium Nitrate and Ammonium Sulfate

To replace explosive nitrate-based chemicals in MS medium, this study developed a new, safer, and more cost-effective method using fertilizer-grade calcium ammonium nitrate and ammonium sulfate. This approach replaces ammonium nitrate and potassium nitrate, ensuring both safety and cost efficiency for sugarcane propagation. Six local sugarcane varieties-Zhongtang1 (ZT1), Zhongtang3 (ZT3), Zhongtang6 (ZT6), Guitang42 (GT42), Guitang44 (GT44), and Guiliu 07150 (GT07150)-were used. In the control group (Ck), nitrate ions (NO3-) were 39.28 mM, and ammonium ions (NH4+) were 20.49 mM, with a 2:1 ratio. In the treatment groups, the concentrations of nitrate ions (NO3-) and ammonium ions (NH4+) included treatment 1 (19.69 mM NO3- and 10.3 mM NH4+), treatment 2 (29.54 mM and 15.44 mM), treatment 3 (39.38 mM and 20.59 mM), treatment 4 (49.225 mM and 25.74 mM), treatment 5 (59.07 mM and 30.89 mM), and treatment 6 (68.915 mM and 36.03 mM), respectively, all with the same 2:1 ratio. Fifty bottles per treatment, with three replicates, were used for each sugarcane plantlets treatment. After five subcultures, the optimal ratio was determined by assessing morphological and physiological parameters, nitrogen levels, and SOD enzyme activity. The results indicated that treatment 3 (39.38 mM and 20.59 mM) and treatment 4 (49.225 mM and 25.74 mM) had the best morphological and physiological indicators. The optimal doses of calcium ammonium nitrate and ammonium sulfate were found in treatments 3 and 4, as well as in the control, with no significant difference among them. However, treatment 3, due to its lower dose, was more cost effective. To improve cost efficiency in practical production, it is recommended to use the lower concentration ratio of treatment 3 for plant tissue culture plantlets.

Effect of gamma irradiation on proliferation and growth of friable embryogenic callus and in vitro nodal cuttings of ugandan cassava genotypes

Cassava (Manihot esculenta Crantz) production and productivity in Africa is affected by two viral diseases; cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Induced mutagenesis of totipotent/embryogenic tissues or in vitro plant material can lead to the generation of CMD and/or CBSD tolerant mutants. To massively produce non-chimeric plants timely and with less labor, totipotent cells or tissues are a pre-requisite. This study aimed to determine the effect of gamma radiation on the proliferation and growth of friable embryogenic callus (FEC) and in vitro nodal cuttings respectively. To obtain FEC, 2-6 mm sized leaf lobes of nine cassava genotypes were plated on Murashige and Skoog (MS) basal media supplemented with varying levels (37, 50, 70, 100) μM of picloram for production of organized embryogenic structures (OES). The OES of five cassava genotypes (Alado, CV-60444, NASE 3, NASE 13 and TME 204) were crushed and plated in Gresshoff and Doy (GD) basal media in combination with the amino acid tyrosine in varying concentrations for FEC production. FEC from five cassava genotypes and in vitro nodal cuttings of nine genotypes were irradiated using five different gamma doses (0, 5, 10, 15, 20 and 25 Gy) at a dose rate of 81Gy/hr. The lethal dose (LD)50 was determined using the number of roots produced and flow cytometry was done to determine the ploidy status of plants. The highest production of OES was noted in Alado across varying picloram concentrations, while TME 204 obtained the highest amount of FEC. The irradiated FEC gradually died and by 28 days post irradiation, FEC from all five cassava genotypes were lost. Conversely, the irradiated in vitro nodal cuttings survived and some produced roots, while others produced callus. The LD50 based on number of roots varied from genotype to genotype, but plants remained diploid post-irradiation. Accordingly, the effect of gamma irradiation on Ugandan cassava genotypes (UCGs) was genotype-dependent. This information is foundational for the use of in vitro tissues as target material for cassava mutation breeding.

A First Approach for the In Vitro Cultivation, Storage, and DNA Barcoding of the Endangered Endemic Species Euonymus koopmannii

Euonymus koopmannii is a rare and protected species in Kazakhstan, valued for its ecological role in soil stabilization and its ornamental properties. This study presents the first use of micropropagation and phylogenetic analysis for the endemic plant E. koopmannii. Seedlings of E. koopmannii proved to be more effective than internodes as primary explants for plant micropropagation of in vitro culture, with a multiplication coefficient of 28.5 from seedlings and 6.1 from internodes. On MSR I medium supplemented with 0.5 mg/L IBA and 0.05 mg/L IAA, a higher success rate of 67% was achieved for root formation of test tube-grown E. koopmannii plants. Using mannitol as an osmotic agent at a concentration of 8 mg/L prolonged the storage time of E. koopmannii under slow growth conditions when compared to CCC and abscisic acid. Phylogenetic relationships and species identification were analyzed using four DNA-barcoding markers, comparing E. koopmannii with species from NCBI. All candidate barcoding markers showed sufficient levels of interspecific genetic variation among Euonymus species. In addition, ITS region and rbcL gene sequences effectively distinguished E. koopmannii from other species. These results provide fundamental information that will be valuable for future biotechnological and molecular studies.

Genome-Wide Association Analysis Identifies Candidate Loci for Callus Induction in Rice (Oryza sativa L.)

Callus induction (CI) is a critical trait for transforming desirable genes in plants. A genome-wide association study (GWAS) analysis was conducted on the rice germplasms of 110 Indica rice accessions, in which three tissue culture media, B5, MS, and N6, were used for the CI of those rice panels' mature seeds. Seven quantitative trait loci (QTLs) on rice chromosomes 2, 6, 7, and 11 affected the CI percentage in the three media. For the B5 medium, one QTL (qCI-B5-Chr6) was identified on rice chromosome 6; for the MS medium, two QTLs were identified on rice chromosomes 2 and 6 (qCI-MS-Chr2 and qCI-MS-Chr6, respectively); for the N6 medium, four QTLs were identified on rice chromosomes 6, 7, and 11 (qCI-N6-Chr6.1 and qCI-N6-Chr6.2, qCI-N6-Chr7, and qCI-N6-Chr11, respectively). Fifty-five genes were identified within the haplotype blocks corresponding to these QTLs, thirty-one of which showed haplotypes associated with different CI percentages in those media. qCI-B5-Chr6 was located in the same region as qCI-N6-Chr6.2, and the Caleosin-related family protein was also identified in this region. Analysis of the gene-based haplotype revealed the association of this gene with different CI percentages in both B5 and N6 media, suggesting that the gene may play a critical role in the CI mechanism. Moreover, several genes, including those that encode the beta-tubulin protein, zinc finger protein, RNP-1 domain-containing protein, and lysophosphatidic acid acyltransferase, were associated with different CI percentages in the N6 medium. The results of this study provide insights into the potential QTLs and candidate genes for callus induction in rice that contribute to our understanding of the physiological and biochemical processes involved in callus formation, which is an essential tool in the molecular breeding of rice.

Enhancing Micropropagation of Adenophora liliifolia: Insights from PGRs, Natural Extracts, and pH Optimization

The endangered plant species Adenophora liliifolia faces threats to its survival in the wild, necessitating the development of effective micropropagation techniques for potential reintroduction efforts. This study demonstrates that Adenophora liliifolia effectively reproduces on MS synthetic medium with diverse plant growth regulators (PGR) and natural extracts, facilitating swift micropropagation for potential future reintroduction endeavors. It highlights the substantial impact of PGR composition and natural extracts on the growth and development of A. liliifolia. The ideal growth medium for A. liliifolia was determined to be ½ MS with specific treatments. Additionally, incorporating silver nitrate (AgNO3) at 5 mg L-1 into the medium led to enhanced root formation and shoot length, albeit excessive concentrations adversely affected root development. Varying concentrations of NAA significantly affected different plant growth parameters, with the 0.1 mg L-1 treatment yielding comparable plant height to the control. Moreover, 50 mL L-1 of coconut water bolstered root formation, while 200 mL L-1 increased shoot formation during in vitro propagation. However, elevated doses of coconut water (CW) impeded root development but stimulated shoot growth. Experiments measuring chlorophyll a + b and carotenoid content indicated higher concentrations in the control group than differing levels of applied coconut water. Optimizing pH levels from 6.8-7 to 7.8-8.0 notably enhanced plant height and root formation, with significant carotenoid accumulation observed at pH 6.8-7. Soil samples from A. liliifolia's natural habitat exhibited a pH of 6.65. Ultimately, the refined in vitro propagation protocol effectively propagated A. liliifolia, representing a pioneering effort and setting the stage for future restoration initiatives and conservation endeavors.

In Vitro Collection for the Safe Storage of Grapevine Hybrids and Identification of the Presence of Plasmopara viticola Resistance Genes

This paper focuses on the creation of an in vitro collection of grapevine hybrids from the breeding program of the Kazakh Scientific Research Institute of Fruit Growing and Viticulture and investigates the presence of Plasmopara viticola resistance mediated by Rpv3 and Rpv12 loci. We looked at the optimization of in vitro establishment using either shoots taken directly from field-grown plants or from budwood cuttings forced indoors. We further screened for the presence of endophyte contamination in the initiated explants and optimized the multiplication stage. Finally, the presence of the resistance loci against P. viticola was studied. The shoots initiated from the field-sourced explants were the more effective method of providing plant sources for in vitro initiation once all plant accessions met the goal of in vitro establishment. The concentration of phytohormones and the acidity of the culture medium have a great effect on the multiplication rate and the quality of in vitro stock cultures. Out of 17 grapevine accessions, 16 showed the presence of single or combined resistance loci against P. viticola. The grapevine accessions identified as carrying Rpv3 and Rpv12 alleles represent important genetic resources for disease resistance breeding programs. These accessions may further contribute to the creation of new elite cultivars of economic interest.

Genome-Wide Analysis of Aux/IAA Gene Family in Artemisia argyi: Identification, Phylogenetic Analysis, and Determination of Response to Various Phytohormones

Artemisia argyi is a traditional herbal medicine plant, and its folium artemisia argyi is widely in demand due to moxibustion applications globally. The Auxin/indole-3-acetic acid (Aux/IAA, or IAA) gene family has critical roles in the primary auxin-response process, with extensive involvement in plant development and stresses, controlling various essential traits of plants. However, the systematic investigation of the Aux/IAA gene family in A. argyi remains limited. In this study, a total of 61 Aux/IAA genes were comprehensively identified and characterized. Gene structural analysis indicated that 46 Aux/IAA proteins contain the four typical domains, and 15 Aux/IAA proteins belong to non-canonical IAA proteins. Collinear prediction and phylogenetic relationship analyses suggested that Aux/IAA proteins were grouped into 13 distinct categories, and most Aux/IAA genes might experience gene loss during the tandem duplication process. Promoter cis-element investigation indicated that Aux/IAA promoters contain a variety of plant hormone response and stress response cis-elements. Protein interaction prediction analysis demonstrated that AaIAA26/29/7/34 proteins are possibly core members of the Aux/IAA family interaction. Expression analysis in roots and leaves via RNA-seq data indicated that the expression of some AaIAAs exhibited tissue-specific expression patterns, and some AaIAAs were involved in the regulation of salt and saline-alkali stresses. In addition, RT-qPCR results indicated that AaIAA genes have differential responses to auxin, with complex response patterns in response to other hormones, indicating that Aux/IAA may play a role in connecting auxin and other hormone signaling pathways. Overall, these findings shed more light on AaIAA genes and offer critical foundational knowledge toward the elucidation of their function during plant growth, stress response, and hormone networking of Aux/IAA family genes in A. argyi.