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Efficient adventitious root formation is essential in micropropagation. Auxin prodrugs, inactive precursors that convert into active auxins within the plant, offer potentially improved rooting control and reduced phytotoxicity. This study investigated the efficacy of dichlorprop ester (DCPE), commercialized as Corasil® and Clemensgros® (originally intended to increase grapefruit size), in promoting in vitro root initiation in the model plant Populus × canadensis, compared to its hydrolyzed form DCP and the related compound C77. DCPE displayed a stronger root-inducing effect than DCP, especially at lower concentrations (0.01 and 0.1 µM). Notably, at 1 µM, both DCP and DCPE induced abundant aerial root formation, a phenomenon not previously observed in poplar with traditional auxin treatments. Metabolite analysis revealed distinct patterns. DCPE treatment resulted in rapid hydrolysis to DCP, leading to faster and more systemic distribution of the active auxin throughout the plant, compared to direct DCP application. C77 treatments showed slower uptake and limited translocation combined with slow metabolism to DCP. These results highlight the potential of auxin prodrugs like DCPE as an effective and controllable auxin source for optimizing in vitro rooting protocols in woody plant species. [ABSTRACT FROM AUTHOR]

A stable tetraploid date palm mutant with the potential for increased fruit size was recovered from a sectorial di-tetraploid chimera via the in vitro culture of flower explants. Callus was induced using 2,4-D, followed by shoot regeneration on a medium containing NAA and BAP and rooting with IBA. Regenerated plantlets, confirmed as tetraploid via flow cytometry, were acclimatized and grown for six years. The leaves of tetraploids exhibited significantly wider petiole bases, thicker rachis and spines, broader leaflets, and a more intense green leaf color compared to diploids. However, leaf length, spine count, and overall leaf number were reduced. This is the first report of successful tetraploid recovery from a chimeric date palm, demonstrating the potential of this technique to generate novel germplasm and highlighting the phenotypic differences associated with tetraploidy in this species. [ABSTRACT FROM AUTHOR]

Lavender (Lavandula angustifolia Mill.) is a valuable crop with diverse applications, but its in vitro rooting can be hindered by its sensitivity to natural auxins and it often fails to root due to callus formation. The current study investigates the effects of light spectra emitted by LEDs and the application of trans-cinnamic acid (t-CA) on the morphology, propagation, and rooting of lavender shoots in vitro. Initially, the influence of different concentrations of t-CA (0, 1.25, 2.5, or 5 µM) was evaluated under fluorescent light. The application of 1.25 µM t-CA was found to be the most effective in promoting root development while minimizing callus formation. Subsequently, the impact of different light spectra (fluorescent light and combinations of blue, red, and far-red monochromatic LED light) was explored. The combination of red and far-red (RFR) light significantly accelerated rooting and resulted in the most substantial increase in root number and length. Finally, the combined effects of 1.25 µM t-CA and RFR light were assessed. This combination produced the most favorable overall results, notably, a 4.3-fold increase in lateral root number compared to RFR light alone. These findings underscore the potential of optimizing both t-CA concentration and light spectra to enhance the in vitro propagation of lavender. [ABSTRACT FROM AUTHOR]

Fluorinated cytokinins have emerged as promising alternatives to traditional cytokinins in Phalaenopsis plant tissue culture, offering enhanced stability and bioactivity. However, their metabolic fate and impact on endogenous cytokinin profiles remain largely unexplored. This study builds upon previous research to investigate the comparative metabolism of the traditional cytokinin 6-Benzylaminopurine (BA) with the successful alternatives 6-(3-fluorobenzylamino)purine (FmT) and 6-(3-fluorobenzylamino)purine 9-riboside (FmTR). Additionally, this study examines the impact of another crucial factor, the use of ventilated versus closed containers, on metabolic processes. The results revealed the distinct metabolic profiles associated with each treatment, highlighting the complex interplay between exogenous and endogenous cytokinin levels. This study is the first to investigate the effects of these stable, synthetic, and exogenous cytokinins on the naturally occurring cytokinin levels and their metabolites in micropropagated Phalaenopsis. Additionally, we proposed an alternative inactivation pathway involving the conversion of FmTR and BA to pT and pTR. These findings provide valuable insights into the intricate relationship between cytokinin metabolism and plant growth under in vitro conditions. [ABSTRACT FROM AUTHOR]

Hardy geranium is a popular ornamental plant with a high market demand. As a result, there is a strong need for continuous innovation to improve its ornamental qualities. Interspecific hybridization is a widely used technique for introducing desirable traits and creating new cultivars with added value. To explore the possibilities of creating novelty within the Geranium genus, we conducted 2438 interspecific crosses over three flowering seasons, resulting in the successful harvest of 445 seeds and the final production of 82 seedlings. Using embryo rescue increased the germination rate of a seedling from 0.17% to 1.01%. To validate the paternal genetic contribution in the new seedlings, we used amplified fragment length polymorphism (AFLP) to assess the proportion of uniquely inherited paternal markers in all seedlings. AFLP analysis confirmed that 54 of the 82 seedlings were indeed true hybrids (65.8% hybridization success rate). A morphological evaluation of the flowers and leaves, including flower diameter (mm), style length (mm), number of flowers, flowering period (weeks), and color of both flowers and leaves, provided further confirmation of the F1 hybrid status of the seedlings. The results of our interspecific breeding demonstrated the efficiency of interspecific hybridization in hardy geraniums and its potential to create distinctive and novel cultivars for the ornamental market. [ABSTRACT FROM AUTHOR]

To date, in vitro somatic embryogenesis is the only option for the mass vegetative propagation of cocoa. The somatic embryogenesis of Indonesian cocoa clones SUL1 and SUL2 was investigated, focusing on primary and cyclic secondary embryogenesis. The study showed that staminode explants were more effective than petal explants in generating primary somatic embryos (SEs), especially when cultured in liquid medium containing 2 mg/L 2,4-D and 0.25 mg/L kinetin, with the staminodes of SUL2 producing a significant number of globular SEs. In contrast, SUL1 showed limited SE production. The study also demonstrated that fragmenting cotyledons and hypocotyls of the SEs of SUL2 and culturing them on an induction medium supplemented with 2,4,5-T and proline resulted in a high yield of secondary SEs. This cyclic embryogenesis process, in which the SEs remained attached to the maternal tissue, facilitated continuous SE production and development. The addition of proline was found to improve the quality of SEs, leading to higher production of well-organized, milky SEs with a better-defined meristematic structure. These results suggest a promising protocol to produce SEs from cocoa, with implications for plant transformation and gene editing applications. [ABSTRACT FROM AUTHOR]

Potato propagation through tubers and seed is an inefficient way of propagation thus we propose an alternative method in this study which is in vitro propagation. Plantlets were raised from True Potato Seeds (TPS) in test tubes containing 10 mL of Murashige Skoog (MS) medium. Subculturing was done after every 21 days and after four subsequent subculturing, when there was an adequate quantity of stock material, uninodal cuttings of about 3–4 mm in length were prepared from in vitro proliferated potato plants by excising leaves of 1–2 mm on each side of the node. Prepared uninodal cuttings were cultured on ½ strength MS medium for root primordia development. The selected uninodal cuttings with root primordia were encapsulated with sodium alginate solution (3.5% (w/v), mixed with 1.25% charcoal and different concentration of fungicide (thiophanate methyl, sigma) to enhance the viability percentage of synthetic seed. Furthermore, these encapsulated uninodal cuttings were subjected to different storage intervals to check maximum storage. Results showed that optimum dose for fungicide is 150 mg/L as it resulted in good viability percentage, shoot number, shoot length, rooting percentage, root number, root length and ideal for bead formation with sodium alginate. Similarly, results revealed that encapsulated uninodal cuttings can be stored at a temperature of 4°C up to 45 days with a survival rate of 63.33%. Encapsulated uninodal cutting stored for 60 days showed a poor viability percentage of about 43.03%. It can be concluded that optimum dose of 150 mg/L with storage time of 45 days should be used to get a better outcome for synthetic potato seed production. [ABSTRACT FROM AUTHOR]

Increasing crop productivity is our major challenge if we are to meet global needs for food, fodder and fuel. Controlling the content of the plant hormone cytokinin is a method of improving plant productivity. Cytokinin oxidase/dehydrogenase (CKO/CKX) is a major target in this regard because it degrades cytokinins. Here, we describe the synthesis and biological activities of new CKX inhibitors derived mainly from diphenylurea. They were tested on four CKX isoforms from maize and Arabidopsis, where the best compounds showed IC 50 values in the 10–8 M concentration range. The binding mode of the most efficient inhibitors was characterized from high-resolution crystal complexed structures. Although these compounds do not possess intrinsic cytokinin activity, we have demonstrated their tremendous potential for use in the plant tissue culture industry as well as in agriculture. We have identified a key substance, compound 19, which not only increases stress resistance and seed yield in Arabidopsis, but also improves the yield of wheat, barley and rapeseed grains under field conditions. Our findings reveal that modulation of cytokinin levels via CKX inhibition can positively affect plant growth, development and yield, and prove that CKX inhibitors can be an attractive target in plant biotechnology and agriculture. [ABSTRACT FROM AUTHOR]

The effect of 10 µM meta-topolin (mT) and meta-topolin riboside (mTR) on in vitro proliferation and anomalies of Pistacia vera L. were evaluated and compared to that of 6-benzylaminopurine (BA). The highest proliferation rate (15.6) was recorded in the mT-medium, with a value 6 times higher than in BA-medium. Moreover, the lowest percentage of hyperhydric usable shoots (58,9%) and callus weight (46,9%) were found in mTR-treated shoots. Shoot tip as well as leaf necrosis were not influenced by cytokinin (CK) type. Image analysis was used to evaluate photosynthetic efficiency as well as anthocyanin index. Photosynthesis was more efficient with BA and mTR but the higher anthocyanin accumulation in BA-treated shoots suggests more stress. Endogenous CKs and their metabolites were determined in seedlings and, for the first time, the metabolism of exogenous BA, mT and mTR was studied in pistachio. The stimulating effect on cis-zeatin and its riboside and the appearance of BA and traces of ortho-topolin and para-topolin as natural CKs are discussed. The quantitative and qualitative CK metabolite analyses provides some initial clues as to why topolin would be superior to BA in terms of proliferation rate and avoiding hyperhydricity and allowed a better understanding of the effect of exogenous administration of CK., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Breeding programs in ornamentals can be facilitated by integrating knowledge of phylogenetic relatedness of potential parents along with other genomic information. Using AFLP, genetic distances were determined for 59 Geranium genotypes, comprising 55 commercial cultivars of the three subgenera of a total collection of 61 Geranium genotypes. A subgroup of 45 genotypes, including intragroup and intergroup hybrids, were selected and further characterized for genome sizes and chromosome numbers. The variation in genome size ranged from 1.51 ± 0.01 pg/2C to 12.94 ± 0.07 pg/2C. The chromosome numbers ranged from 26 to 108-110 with some hybrids showing an aberrant number of chromosomes based on their parents' constitution. All chromosome numbers of Geranium are an even number, which presumes that unreduced gametes occur in some cross combinations. Overall, parental difference in genome size and chromosome number were not limiting for cross compatibility. Good crossing compatibility was correlated to a Jaccard similarity coefficient as parameter for parental relatedness of about 0.5. Additionally, parent combinations with high differences in the DNA/chromosome value could not result in a successful cross. We expect that our results will enable breeding programs to overcome crossing barriers and support further breeding initiatives.

Since 2017, a new leaf wilt syndrome was observed in plantations of date palm in Tunisia. Its incidence increases sharply from year to year, especially in 'Deglet Nour' trees, aged between 5 and 15 years. In severe cases, the large number of dried leaves per tree can lead to complete cessation of date production. Symptoms appear on one or more leaves in the center of the crown. Whitening and drying start at the top of the leaflets and proceed to their base, while the midrib remains green. Then the whole leaf dies. Small white-creamy leaflet fragments and roots were collected from five different regions in the Djerid Oases. They were disinfected with diluted bleach (0,8 % NaOCl) and ethanol (80%) (each 2 min), rinsed with sterile distilled water, dried and finally plated in Petri dishes containing Potato Dextrose Agar (PDA) amended with 50mg/l neomycin. After incubation for 7 days at 25ºC±2, emerging fungal colonies were single-spored by serial dilution. They were transferred to PDA, Carnation Leaf Agar (CLA) and Spezieller Nahrstoffarmer Agar (SNA) for morphological identification. Based on the colony color on PDA, conidial morphology and phialide structures on CLA and/or SNA, of the 85 Fusarium isolates, around 90% were identified as F. proliferatum and around 10% as F. brachygibbosum (Leslie and Summerell, 2006). Fusarium proliferatum colonies rapidly developed white aerial mycelium that became purple in old cultures. Microconidia were abundant in the aerial mycelium and formed chains of variable length, on monophialides and polyphialids, a characteristic that distinguishes F. proliferatum from F. verticilloides. Less often, they were observed in false heads. Chlamydospores were absent. On CLA, microconidia were mostly 2 × 15 µm in size, a large number of sickle shaped macroconidia (2 × 25 µm) had one septum, some were larger (2 × 50 µm) with 3 septa and tips at both ends. Molecular identification was carried out based on elongation factor (EF-1α) gene sequencing. The region between the EF1 and EF2 primers (O'Donnell et al., 1998) was amplified and the sequences were compared to Fusarium reference sequences (GenBank). The sequences of the isolates Fus 1953 (539 bp), Fus 1962 (618 bp), and Fus 1965 (605 bp) shared respectively 100%, 99.51% and 99.51% homology with that of F. proliferatum JF740713.1 and were deposited in GenBank with the following accession numbers: MT630418, MT630419, and MT630420, respectively. The sequences of isolates 7F, 28F, Fus 1955 and Fus 1956 shared 100 % homology with that of F. brachygibbosum (GQ505418.1) while those of Fus 1955 and Fus 1956 showed 99.02 and 98.91 % identity, respectively, with F. brachygibbosum JX118981.1. The sequences of 7F (535 bp), 28F (535 bp), Fus 1955 (608 bp), and Fus 1956 (647 bp) were deposited in GenBank with the following accession numbers: MT630409, MT630410, MT630411, and MT630412, respectively. Two ml suspension of 106 conidia / ml of each isolate was sprayed separately or in combinations on in vitro cloned 'Deglet Nour' plants, placed in a greenhouse at 28°±2 °C and 70% R.H.. Isolates of F. proliferatum led to dryness and wilting leaflets after 3 weeks. Fusarium brachygibbosum only induced mild leaf yellowing, while in combination they were more virulent. Fungal isolates of both species were re-isolated and their identity confirmed to be the same of those isolated from leaflets infected in the open field, confirming Koch's postulates. Control plants lacked symptoms. Fusarium proliferatum is known as date palm pathogen in many countries (Saleh et al. 2017), however, to our knowledge, this is the first report of F. proliferatum and also F. brachygibbosum causing Leaf Wilt symptoms on P. dactylifera in Tunisia.

Due to potential health and environmental risks of synthetic pesticides, coupled with their non-selectivity and pest resistance, there has been increasing demand for safer and biodegradable alternatives for insect pest management. Botanical pesticides have emerged as a promising alternative due to their non-persistence, high selectivity, and low mammalian toxicity. Six Meliaceae plant species, Azadirachta indica, Azadirachta excelsa, Azadirachta siamens, Melia azedarach, Melia toosendan , and Melia volkensii, have been subject to botanical pesticide evaluation . This review focuses on Melia volkensii , which has not been intensively studied. M. volkensii, a dryland tree species native to East Africa, has shown activity towards a broad range of insect orders, including dipterans, lepidopterans and coleopterans. Its extracts have been reported to have growth inhibiting and antifeedant properties against Schistocerca gregaria, Trichoplusia ni , Pseudaletia unipuncta , Epilachna varivestis, Nezara viridula , several Spodoptera species and other insect pests. Mortality in mosquitoes has also been reported. Several limonoids with a wide range of biological activities have been isolated from the plant, including volkensin, salannin, toosendanin, trichilin-class limonoids, volkendousin, kulactone among others. This paper presents a concise review of published information on the phytochemical composition and potential of M. volkensii for application in insect pest management., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.