Search

Phytohormone levels are regulated through specialized enzymes, participating not only in their biosynthesis but also in post-signaling processes for signal inactivation and cue depletion. Arabidopsis thaliana (At) carboxylesterase 15 (CXE15) and carboxylesterase 20 (CXE20) have been shown to deplete strigolactones (SLs) that coordinate various growth and developmental processes and function as signaling molecules in the rhizosphere. Here, we elucidate the X-ray crystal structures of AtCXE15 (both apo and SL intermediate bound) and AtCXE20, revealing insights into the mechanisms of SL binding and catabolism. The N-terminal regions of CXE15 and CXE20 exhibit distinct secondary structures, with CXE15 characterized by an alpha helix and CXE20 by an alpha/beta fold. These structural differences play pivotal roles in regulating variable SL hydrolysis rates. Our findings, both in vitro and in planta, indicate that a transition of the N-terminal helix domain of CXE15 between open and closed forms facilitates robust SL hydrolysis. The results not only illuminate the distinctive process of phytohormone breakdown but also uncover a molecular architecture and mode of plasticity within a specific class of carboxylesterases.

The use of natural plant growth regulators (PGRs) as ecofriendly agrochemicals is gaining much attention, but the fate of these compounds once they enter the soil environment is poorly understood. In this work, we compared the plant growth inhibitory activity of the phytohormone S-abscisic acid (S-ABA) in the presence of three soils with that observed in soilless (Petri dish) conditions and related the differences in activity to the sorption and dissipation processes of the phytohormone in the soils. In Petri dishes, S-ABA inhibited the germination of Eruca sativa, Allium porrum, Lactuca sativa, and Hordeum vulgare with mean inhibitory concentration values (IC50) in the range of 0.5–8.2 mg/L. Eruca sativa was selected for subsequent studies based on its high sensitivity to S-ABA (IC50 = 0.5 mg/L). The inhibition of germination of E. sativa by S-ABA was fully reversible at a low phytohormone concentration (5 mg/L) and partially reversible at a higher phytohormone concentration (60 mg/L). S-ABA also inhibited the growth of pre-germinated seedlings of E. sativa, albeit at higher concentrations than those at which it inhibited germination. The three soils used in the study weakened the inhibitory activity of S-ABA by soil factors in the range of 0.008–0.380. As S-ABA displayed low or even negative sorption in the soils tested, the decrease in the activity of S-ABA was attributed to its biodegradation in the soils, rather than to a decrease in its bioavailability due to sorption. Despite the reduction in the activity of S-ABA observed in the presence of the soils, the phytohormone still expressed its activity at quite low soil concentrations (0.3–20 mg/kg), showing higher activity in soils where the compound degraded more slowly. [ABSTRACT FROM AUTHOR]

In the context of anthropogenic evolution, various sectors have been exploited to satisfy human needs and demands, often pushing them to the brink of deterioration and destruction. One such sector is agrochemicals, which have been increasingly employed to achieve higher yields and bridge the gap between food supply and demand. However, extensive and prolonged use of chemical fertilizers most often degrades soil structure over time, resulting in reduced yields and consequently further exacerbating the disparity between supply and demand. To address these challenges and ensure sustainable agricultural production, utilization of microorganisms offers promising solutions. Hence, microorganisms, particularly effective microorganisms (EMs) and plant growth-promoting microbes (PGPMs), are pivotal in agricultural biomes. They enhance crop yields through active contribution to crucial biological processes like nitrogen fixation and phytohormone synthesis, making vital nutrients soluble and acting as natural enemies against pests and pathogens. Microbes directly enhance soil vigor and stimulate plant growth via the exudation of bioactive compounds. The utilization of EMs and PGPMs reduces the need for chemical inputs, leading to lower costs and reduced environmental pollutants. Furthermore, beneficial soil microflora produces growth-related metabolites and phytohormones that augment plant growth and support stress resilience. Microbes also help plants tolerate various abiotic stresses, including metal stress, salt stress, and drought stress, through various mechanisms. Understanding the interactions and activities of microorganisms provides valuable insights into their potential use to manage stress in plants. Thus, by leveraging the full potential of microorganisms, we can develop healthier agroecosystems that contribute sustainably to meet the growing global food demands. [ABSTRACT FROM AUTHOR]

Plants are an important source for the discovery of novel natural growth regulators. We used activity screening to demonstrate that treatment of Nipponbare seeds with 25 μg/mL isopimaric acid significantly increased the resulting shoot length, root length, and shoot weight of rice seedlings by 11.37 ± 5.05%, 12.96 ± 7.63%, and 27.98 ± 10.88% and that it has a higher activity than Gibberellin A3 (GA3) at the same concentration. A total of 213 inbred lines of different rice lineages were screened, and we found that isopimaric acid had different growth promotional activities on rice seedlings of different varieties. After induction with 25 μg/mL isopimaric acid, 15.02% of the rice varieties tested showed increased growth, while 15.96% of the varieties showed decreased growth; the growth of the remaining 69.02% did not show any significant change from the control. In the rice varieties showing an increase in growth, the shoot length and shoot weight significantly increased, accounting for 21.88% and 31.25%. The root length and weight significantly increased, accounting for 6.25% and 3.13%. Using genome-wide association studies (GWASs), linkage disequilibrium block, and gene haplotype significance analysis, we identified single nucleotide polymorphism (SNP) signals that were significantly associated with the length and weight of shoots on chromosomes 2 and 8, respectively. After that, we obtained 17 candidate genes related to the length of shoots and 4 candidate genes related to the weight of shoots. Finally, from the gene annotation data and gene tissue-specific expression; two genes related to this isopimaric acid regulation phenotype were identified as OsASC1 (LOC_Os02g37080) on chromosome 2 and OsBUD13 (LOC_Os08g08080) on chromosome 8. Subcellular localization analysis indicated that OsASC1 was expressed in the plasma membrane and the nuclear membrane, while OsBUD13 was expressed in the nucleus. Further RT-qPCR analysis showed that the relative expression levels of the resistance gene OsASC1 and the antibody protein gene OsBUD13 decreased significantly following treatment with 25 μg/mL isopimaric acid. These results suggest that isopimaric acid may inhibit defense pathways in order to promote the growth of rice seedlings. [ABSTRACT FROM AUTHOR]

Cymbidium faberi, a member of the Cymbidium genus known for its fragrant blooms and graceful foliage, has recently become endangered in the wild due to reproductive challenges. This study aimed to establish systematically a tissue culture system for Cymbidium faberi Rolfe (wild species) by evaluating the effects of various plant growth regulators its propagation stages, including rhizome proliferation, differentiation, shoot strengthening, and rooting. The results showed that 0.5 mg⋅L-1 thidiazuron significantly promoted rhizome proliferation, achieving a proliferation coefficient of 6.08 after 60 days of culture. For adventitious bud induction, 1.92 mg⋅L-1 brassinolide was most effective, inducing 6.43 buds per rhizome with an average bud height of 5.25 mm after 90 days of culture. The optimal strategy for shoot growth was using 3.0 mg⋅L-1 1-naphthaleneacetic acid, resulting in an average shoot height of 6.47 cm after 60 days. The highest rooting rate of 87.5% was achieved with 0.5 mg⋅L-1 zeatin, producing an average of 3.5 roots per shoot with an average root length of 3.06 cm. This study successfully developed a propagation system for C. faberi and highlighted the significant role of BL in promoting rhizome differentiation. In conclusion, this study provides a robust propagation method to support the conservation and industrial development of C. faberi. [ABSTRACT FROM AUTHOR]

• Potato, being an important food crop, persuades the researchers owing to its edible nutrition-rich tubers. • This short-review critically analyses how physical and chemical factors influence in vitro regeneration of potato. • Features main obstacles and possible solutions to warrant high-frequency regeneration of propagules. • Identifies research gaps that need to be addressed to ensure an enhanced micropropagation system. Potato (Solanum tuberosum L.) is one of the most important food crops widely cultivated worldwide due to its edible and nutrition-rich tubers. It is a temperate crop; however, currently, it is grown in a wide range of areas with distinctive climatic conditions. Traditionally, potato is propagated by whole or cut tubers and true potato seeds. Owing to the low rate of multiplication and high cost of cultivation to produce virus-free planting material during traditional propagation, the in vitro technique becomes an alternative approach to conventional propagation. Over the past ten years, significant advancements have been made in the optimization of protocols for several varieties/cultivars of potato via a direct regeneration-mediated approach. The present short-review illustrates the analysis of an array of significant published findings on various physical and chemical variables that are responsible for fruitful in vitro direct regeneration and microtuberization of potato. Furthermore, this short-review describes a number of undiscovered areas, research gaps, and major problems that might be accounted for advancing noteworthy ingenious approaches associated with potato biotechnology in the near future. The current short-review further addresses salient recommendations and conclusions (based on achievements during the last ten-year period), paving the way for potato researchers to work on several unexplored areas in the coming years. [ABSTRACT FROM AUTHOR]

• Paphiopedilum spp. is known as lady slipper orchid. • Embryogenesis in Paphiopedilum spp. can be induced with plant growth regulator. • Development of somatic embryos in Paphiopedilum spp. is the same as zygotic embryos. • The homologous embryo gene RKD4 is present and functional in Paphiopedilum spp. Paphiopedilum spp. is one of the terrestrial orchids that is interesting as an ornamental plant. This orchid flower has a distinctive characteristic, namely its labellum resembles a sac, so it is sought after by ornamental flower collectors because of its uniqueness. This orchid is included in the Appendix I group according to CITES, namely a critical species that is threatened with extinction, so it needs to be conserved both in situ and ex situ. Ex situ conservation can be done by propagating orchids using in vitro culture techniques. The objective of this research is to carry out mass propagation of 3 species of Paphiopedilum spp orchids: P. supardii, P. primulinum, P. glaucophyllum through somatic embryogenesis and to characterize the existence of embryo gene RKD4 homolog in Paphiopedilum orchids. The method is to culture the nodes slices in dark conditions for 2 weeks, and then changed to photoperiod mode 16:8 hours (dark:light) on ½ MS media plus a combination of 2,4-D or NAA with TDZ. The somatic embryo were analyzed anatomically. This method is an improvement over previously reported methods for Paphiopedilum spp. due to its efficiency and reproducibility for conservation. We concluded that ½ MS media with a combination of NAA or 2,4D with TDZ were able to induce somatic embryogenesis. The result show that 3 mg L−1 NAA was the best PGRs for PLBs induction in P. supardii (50 %), 1 mg L−1 2,4-D + 0.5 mg L−1 TDZ was the best PGRs for callus embryogenic induction in P. primulinum (20 %), and 1 mg L−1 NAA was the best PGRs for PLBs induction in P. glaucophyllum (33 %). [ABSTRACT FROM AUTHOR]

Bamboo cultivation, particularly Moso bamboo (Phyllostachys edulis), holds significant economic importance in various regions worldwide. Bamboo shoot degradation (BSD) severely affects productivity and economic viability. However, despite its agricultural consequences, the molecular mechanisms underlying BSD remain unclear. Consequently, we explored the dynamic changes of BSD through anatomy, physiology and the transcriptome. Our findings reveal ruptured protoxylem cells, reduced cell wall thickness and the accumulation of sucrose and reactive oxygen species (ROS) during BSD. Transcriptomic analysis underscored the importance of genes related to plant hormone signal transduction, sugar metabolism and ROS homoeostasis in this process. Furthermore, BSD appears to be driven by the coexpression regulatory network of senescence‐associated gene transcription factors (SAG‐TFs), specifically PeSAG39, PeWRKY22 and PeWRKY75, primarily located in the protoxylem of vascular bundles. Yeast one‐hybrid and dual‐luciferase assays demonstrated that PeWRKY22 and PeWRKY75 activate PeSAG39 expression by binding to its promoter. This study advanced our understanding of the molecular regulatory mechanisms governing BSD, offering a valuable reference for enhancing Moso bamboo forest productivity. Summary statement: The bamboo shoot degradation occurs first in the protoxylem and impacts phytohormone signalling, starch and sucrose metabolism, as well as reactive oxygen species homoeostasis. PeWRKY22 and PeWRKY75 activate PeSAG39 by binding to its promoters. [ABSTRACT FROM AUTHOR]

Preharvest fruit drop is one of the main challenges in apple production as it can lead to extensive crop losses in commercially important cultivars including 'Honeycrisp'. Plant growth regulators, such as aminoethoxyvinylglicine (AVG) and 1-methylcyclopropene (1-MCP), which hinder ethylene biosynthesis and perception, respectively, can control preharvest fruit drop, but an assessment of their effects in 'Honeycrisp' fruit grown under US mid-Atlantic conditions is lacking. In this study, we evaluated the effects of AVG (130 mg a.i. L−1) and 1-MCP (150 mg a.i. L−1) on preharvest fruit drop, ethylene production, fruit physicochemical parameters, skin color, and transcript accumulation of ethylene and anthocyanin-related genes in 'Honeycrisp' apples throughout on-the-tree ripening. We showed that both AVG and 1-MCP significantly minimized preharvest fruit drop with respect to the control fruit. Additionally, AVG was the most effective in decreasing ethylene production, downregulating ethylene biosynthesis and perception-related gene expression, and delaying fruit maturity. Nevertheless, AVG negatively impacted apple red skin color and exhibited the lowest expression of anthocyanin-biosynthesis-related genes, only allowing apples to reach the minimum required 50% blush at the last ripening stage. Conversely, 1-MCP-treated fruit displayed an intermediate behavior between AVG-treated and control fruit, decreasing ethylene production rates and the associated gene expression as well as delaying fruit maturity when compared to the control fruit. Remarkably, 1-MCP treatment did not sacrifice red skin color development or anthocyanin-biosynthesis-related gene expression, thus exhibiting > 50% blush one week earlier than AVG. [ABSTRACT FROM AUTHOR]

Plant growth regulators (PGRs) are well known for their ability to improve plants' tolerance to heavy metals. However, in these treatments, the contribution of native rhizobacteria on heightened tolerance to heavy metals is usually not considered, and thus PGR ability is overestimated. In this study, using duckweed Spirodela polyrhiza as indicating plant and according to the responses of it grown under nonsterile and sterile conditions, native rhizobacteria were able to cooperate with PGRs and thereby improved duckweed's tolerance to Cd stress. All the randomly selected bacterial isolates and salicylic acid exerted synergistic effects that improved Cd tolerance, suggesting that active rhizobacteria are not necessarily plant growth-promoting rhizobacteria (PGPRs). Comparative physiological and transcriptomic analyses showed that the cooperation between the native bacterium Pseudomonas and salicylic acid can greatly reduce Cd accumulation and decrease oxidative stress, thus lowering the requirement of antioxidant defense in duckweed; moreover, the synthesis of flavonoids that facilitates reactive oxygen species scavenging in duckweed was significantly induced. This study recommends that the contribution of native rhizobacteria on improved plant tolerance to heavy metals should be considered when applying PGRs. [ABSTRACT FROM AUTHOR]

In Bangladesh, okra is an important popular summer vegetable. However, traditional farming practices often lead to suboptimal yields. Thus, the study was designed to determine the ideal GA3 and NAA doses for accelerating okra growth, yield, and quality characteristics. A three-replication, randomized complete block design was adopted. Foliar sprays with three concentrations of GA3 (0 ppm, 150 ppm, and 250 ppm) and NAA (0 ppm, 150 ppm, and 250 ppm) were applied in 2022 and 2023. In comparison to the control, the combined application of GA3 @ 150 ppm and NAA @ 150 ppm improved plant height, leaf number, leaf area, branch number, internode length, bud number, pod number, pod length, pod diameter, and 1000 seed weight average over the two years. Furthermore, GA3 @ 150 ppm with NAA 150 ppm increased yield by 35.08% and 27.01% in 2022 and 2023 respectively, above the control. Combining NAA @ 150 ppm with GA3 resulted in higher levels of vitamin C, TSS, magnesium, and zinc by 19.31%, 81.2%, 22.73% and 21.43% in 2022 and 22.83%, 50.57%, 18.07%, 33.33% in 2023 respectively, compared to the control. In contrast, GA3 and NAA decreased potassium and calcium in both year when compared to the control. Overall, the results of this experiment indicated that using GA3 @ 150 ppm with NAA @ 150 ppm could enhance okra growth, yield, and quality. These findings provide insightful information for improving okra cultivation techniques and improving Bangladesh's productivity in agriculture and food security. [ABSTRACT FROM AUTHOR]

Sesame (Sesamum indicum L.) is an important oilseed crop with significant economic importance in many developing countries. This study rigorously investigated the impact of various applications and doses of two specific plant growth regulators, paclobutrazol (PAC) and mepiquat chloride (MC), on the development, yield components, oil content, and fatty acid composition of sesame plants across two consecutive growing seasons. The research revealed that while paclobutrazol application increased the plant height it also resulted in a slight decrease in oil content. The paclobutrazol treatment resulted in the highest seed yield (21.3 g/plant), which was significantly different from both the MC (13.1 g/plant) and PAC + MC (14.6 g/plant) treatments. In contrast, the mepiquat chloride treatment resulted in the lowest oil content. The combined application of both regulators showed intermediate effects. In addition, variations in fatty acid content were observed between applications and doses, with significant differences in saturated and unsaturated fatty acid levels. The findings provide valuable insights into the potential benefits and implications of using growth regulators in sesame cultivation, especially in the context of mechanized harvesting and oil quality optimization. [ABSTRACT FROM AUTHOR]

Coconut palm is of great economic importance and contributes to income generation, employment, nutrition and food security in the commercial sector. Malaysia, which is among the top 10 coconut-producing countries in the world, plays a notable role, while Indonesia is the largest producer. The Matag coconut, a hybrid of the Malayan Yellow Dwarf and Tagnanan Tall varieties, is characterised by its excellent nut quality and higher yield of 25,000 to 30,000 nuts per hectare annually. Despite its fame, the Matag coconut has faced problems, particularly disease susceptibility, which has been accelerated by globalisation and has led to the extinction of many crops. Somatic embryogenesis, an in vitro breeding technique, is a promising avenue for coconut regeneration and micropropagation. However, the genotype dependence and high heterozygosity of coconut lead to variability among the progeny, which limits the effectiveness of this method. The conventional use of fluorescent lamps for in vitro propagation, which are customised to the needs of the plants, has disadvantages such as the generation of unnecessary wavelengths and high energy consumption. The integration of the thin cell layer (TCL) method into tissue culture, particularly via the organogenesis route, is proving to be a transformative technique for coconut propagation. This review highlights the potential enhancement of this novel approach through the use of red and blue light-emitting diodes (LEDs). The use of these LEDs aims to optimise the propagation and acclimatisation of the ‘Matag’ coconut and offers a viable solution for both research and commercial applications. [ABSTRACT FROM AUTHOR]

Compost residue enriches soil health with the potential to enhance plant metabolism and hormonal balance, but has not yet been studied. A study was performed to determine how prevailing compost residue induces tomato (Solanum lycopersicum 'Scotia') plant morpho-physiology, phytohormones, and secondary metabolites. Plants were grown in soils with a previous history of annual (AN) and biennial (BI) compost amendments. The controls were soil without compost (C) amendment and municipal solid waste compost (MSWC) alone. The MSWC- and AN-plants had similar and significantly (p < 0.05) highest growth and photosynthetic activities compared to the BI- or C-plants. Total phenolics and lipid peroxidase activity were significantly (p < 0.001) high in BI-plants, while hydrogen peroxide and antioxidant capacity were significantly (p < 0.001) high in AN-plants. MSWC-plants recorded the highest cis-abscisic acid, followed by AN-, and then BI- and C-plants. Cis-zeatin, trans-zeatin, and isopentenyladenine ribosides were detected in the MSWC- and AN-plants but not in the BI- or C-plants. Furthermore, gibberellins GA53, GA19, and GA8 were high in the MSWC-plants, but only GA8 was detected in the AN plants and none in the others. Besides, MSWC plants exhibited the highest content of 1-aminocyclopropane-1-carboxylic acid. Conjugated salicylic acid was highest in the BI-plants, while jasmonic acid-isoleucine was highest in MSWC-plants and C plants. In conclusion, prevailing compost chemical residues upregulate plant growth, phytohormones, and metabolic compounds that can potentially increase plant growth and abiotic stress defense. Future work should investigate the flow of these compounds in plants under abiotic stress. [ABSTRACT FROM AUTHOR]

Secondary growth in garlic depreciates its visual aspect and thereby renders the crop unviable for trade. Therefore, farmers commonly reduce fertilization and impose drought and oxidative stress caused by high-dose pesticides to reduce secondary growth in garlic plants. However, these procedures can be considered adverse, unhealthy, and environmentally inappropriate. To remedy this scenario, we investigated whether spraying growth inhibitors would prevent secondary growth in garlic plants. First, we evaluated the effects of abscisic acid, trinexapac-ethyl, chlormequat chloride, and paclobutrazol treatments on garlic plants grown in polyethylene tanks (250 m3). We then analyzed the effects of deficit irrigation combined with the application of trinexapac-ethyl (sprayed two or three times) and the application of trinexapac-ethyl, chlormequat chloride, or paclobutrazol alone (each sprayed two or three times) on garlic plants grown in the field, comparing them with the effects of deficit irrigation (control treatment) alone. The in-field experiment was replicated with the following treatments: control (deficit irrigation) and trinexapac-ethyl (sprayed two or three times) treatments. We analyzed the physiological, biometric, and production parameters affecting secondary growth in garlic plants. We observed that trinexapac-ethyl could efficiently regulate secondary growth without causing physiological disturbances in garlic plants. Our results provide valuable information that will contribute to the development of a sustainable technique to replace the current practices used by farmers to prevent secondary growth in garlic plants.

Drought is a major abiotic stress affecting plant growth and productivity worldwide. Henna (Lawsonia inermis L.) is an economically important plant species that is widely cultivated due to its natural dye properties and medicinal uses, and it is highly susceptible to drought stress, which limits its growth and development. This study was conducted with the aim of investigating the effect of foliar spraying of sodium nitroprusside (SNP) on the yield of henna ecotypes (Lawsonia inermis L.) under drought stress conditions in Shahdad-Iran. The experiment was conducted in the form of a split factorial design based on randomized complete block design (RCBD) in three replications. Three ecotypes of henna (Rudbar-e-Jonub, Shahdad, and Bam) were used as plant material. The findings showed that with the onset of drought, photosynthetic pigments, growth indices, net photosynthesis, and yield of dry matter of henna plant leaves decrease. However, when SNP spray treatment was applied, it significantly improved things like leaf area index, crop growth rate, net photosynthesis and leaf dry matter yield, especially when drought levels were at 25 and 50%. The natural water content of Shahdad genotype in henna plants showed the highest percentage increase in these measurements compared with other henna plant species. It can be concluded that SNP spray can increase the yield of henna plant under drought stress conditions.

Abstract In Bangladesh, okra is an important popular summer vegetable. However, traditional farming practices often lead to suboptimal yields. Thus, the study was designed to determine the ideal GA3 and NAA doses for accelerating okra growth, yield, and quality characteristics. A three-replication, randomized complete block design was adopted. Foliar sprays with three concentrations of GA3 (0 ppm, 150 ppm, and 250 ppm) and NAA (0 ppm, 150 ppm, and 250 ppm) were applied in 2022 and 2023. In comparison to the control, the combined application of GA3 @ 150 ppm and NAA @ 150 ppm improved plant height, leaf number, leaf area, branch number, internode length, bud number, pod number, pod length, pod diameter, and 1000 seed weight average over the two years. Furthermore, GA3 @ 150 ppm with NAA 150 ppm increased yield by 35.08% and 27.01% in 2022 and 2023 respectively, above the control. Combining NAA @ 150 ppm with GA3 resulted in higher levels of vitamin C, TSS, magnesium, and zinc by 19.31%, 81.2%, 22.73% and 21.43% in 2022 and 22.83%, 50.57%, 18.07%, 33.33% in 2023 respectively, compared to the control. In contrast, GA3 and NAA decreased potassium and calcium in both year when compared to the control. Overall, the results of this experiment indicated that using GA3 @ 150 ppm with NAA @ 150 ppm could enhance okra growth, yield, and quality. These findings provide insightful information for improving okra cultivation techniques and improving Bangladesh’s productivity in agriculture and food security.

This study was conducted to establish an efficient in vitro regeneration technique for the induction of somatic embryo and plantlet regeneration under NaCl-salt stress conditions in black rice (Oryza sativa. L., cv Co57), a traditional Indian cereal food. Embryogenic calli were obtained from mature caryopsis culture on Murashige and Skoog (1962) medium fortified with 2,4-dichlorophenoxyacetic acid (2.0mg/L) either alone or in combination with various concentrations of NaCl (10mM, 25mM, 50mM, and 100mM) in order to induce the salt tolerant somatic embryo differentiation. Furthermore, embryogenic calli were found to show shoot regeneration on MS-medium fortified with 2.0mg/L of 6-benzylaminopurine (BAP) in combination with 0.5mg/L of α-naphthaleneacetic acid (NAA) and in presence of NaCl (10mM, 25mM, 50mM, and 100mM). Significantly, the high concentration (150mM) of NaCl was proved to be lethal for both somatic embryogenesis as well as plantlets regeneration. Moreover, the low frequency (40.3%) of somatic embryogenesis and minimum number of salt tolerant somatic embryos per callus (3.2±0.1) was recorded with the caryopsis explants that were treated with the high concentration (100mM) of NaCl-salt added embryo induction medium. Significantly, low frequency of salt-tolerant plantlets regeneration (25%) and minimum number of plantlets per embryogenic callus (1.5±0.1) was recorded in the embryogenic callus that was treated with 100mM of NaCl in regeneration medium containing BAP (2.0mg/L) in combination with NAA (0.5mg/L). Further, salinity tolerant plantlets were transferred to soil and gradually acclimatized under growth chamber conditions. This study thus offers a suitable technique for production of salt tolerant black rice, an alternative approach for the traditional Indian black rice crop improvements.

Climate change has exacerbated the effects of abiotic stresses on plant growth and productivity. Drought is one of the most important abiotic stress factors that interfere with plant growth and development. Plant selection and breeding as well as genetic engineering methods used to improve crop drought tolerance are expensive and time consuming. Plants use a myriad of adaptative mechanisms to cope with the adverse effects of drought stress including the association with beneficial microorganisms such as plant growth promoting rhizobacteria (PGPR). Inoculation of plant roots with different PGPR species has been shown to promote drought tolerance through a variety of interconnected physiological, biochemical, molecular, nutritional, metabolic, and cellular processes, which include enhanced plant growth, root elongation, phytohormone production or inhibition, and production of volatile organic compounds. Therefore, plant colonization by PGPR is an eco-friendly agricultural method to improve plant growth and productivity. Notably, the processes regulated and enhanced by PGPR can promote plant growth as well as enhance drought tolerance. This review addresses the current knowledge on how drought stress affects plant growth and development and describes how PGPR can trigger plant drought stress responses at the physiological, morphological, and molecular levels.

Over recent years, our understanding of the tricarboxylic acid cycle (TCAC) in living organisms has expanded beyond its canonical role in cellular energy production. In plants, TCAC metabolites and related enzymes have important roles in physiology, including vacuolar function, chelation of metals and nutrients, photorespiration, and redox regulation. Research in other organisms, including animals, has demonstrated unexpected functions of the TCAC metabolites in a number of biological processes, including signaling, epigenetic regulation, and cell differentiation. Here, we review the recent progress in discovery of non-canonical roles of the TCAC. We then discuss research on these metabolites in the context of plant development, with a focus on research related to tissue-specific functions of the TCAC. Additionally, we review research describing connections between TCAC metabolites and phytohormone signaling pathways. Overall, we discuss the opportunities and challenges in discovering new functions of TCAC metabolites in plants.

The vascular cambium is the main secondary meristem in plants that produces secondary phloem (outside) and xylem (inside) on opposing sides of the cambium. The phytohormone ethylene has been implicated in vascular cambium activity, but the regulatory network underlying ethylene-mediated cambial activity remains to be elucidated. Here, we found that PETAL MOVEMENT-RELATED PROTEIN1 (RhPMP1), an ethylene-inducible HOMEODOMAIN-LEUCINE ZIPPER I transcription factor in woody plant rose (Rosa hybrida), regulates local auxin biosynthesis and auxin transport to maintain cambial activity. Knockdown of RhPMP1 resulted in smaller midveins and reduced auxin content, while RhPMP1 overexpression resulted in larger midveins and increased auxin levels compared with the wild-type plants. Furthermore, we revealed that Indole-3-pyruvate monooxygenase YUCCA 10 (RhYUC10) and Auxin transporter-like protein 2 (RhAUX2), encoding an auxin biosynthetic enzyme and an auxin influx carrier, respectively, are direct downstream targets of RhPMP1. In summary, our results suggest that ethylene promotes an auxin maximum in the cambium adjacent to the xylem to maintain cambial activity.

Medicinal plants have been used historically for various treatments and in human nutrition. Due to their natural occurrence and biodegradability, medicinal plants can be an eco-friendly alternative to toxic chemicals such as pesticides, fungicides, and herbicides. An in vitro experiment was conducted to test the impact of six medicinal plant extracts on tomato growth and callus induction. Two concentrations of each extract (50 and 100 mg L-1) were added to the Murashige and Skoog (MS) medium culture. Results showed that Juniperus sabina extract (50 mg L-1) accelerated tomato seed germination by 100% in vitro, compared to the control group in MS basal medium. Callus growth index (CGI) and callus weight (CW) increased by 50% and by more than 200% when using Taraxacum officinale (100 mg L-1) and Conocarpus erectus (50 mg L-1) extracts, respectively. Biochemical analysis revealed that the extracts were rich in phenolic compounds (348 mg g-1 of total phenol), flavonoids (162 mg g-1), antioxidants (61%), and auxin. A rise in antioxidant activity, plant growth regulators (PGR), and plant defense elicitation probably contributed to these outcomes. Plant extracts also affected the biochemical content of calluses, except for their total phenol. We recommend using these plant extracts to increase growth, accelerate seed germination, and promote callus induction. Optimizing concentrations and combinations of medicinal plant extracts require further research to maximize their benefits to different plant species and their growth-related values. [ABSTRACT FROM AUTHOR]

Abstract Plant growth regulators (PGRs) are involved in multiple aspects of plant life, including plant growth, development, and response to environmental stimuli. They are also vital for the formation of secondary metabolites in various plants. Salvia miltiorrhiza is a famous herbal medicine and has been used commonly for > 2000 years in China, as well as widely used in many other countries. S. miltiorrhiza is extensively used to treat cardiovascular and cerebrovascular diseases in clinical practices and has specific merit against various diseases. Owing to its outstanding medicinal and commercial potential, S. miltiorrhiza has been extensively investigated as an ideal model system for medicinal plant biology. Tanshinones and phenolic acids are primary pharmacological constituents of S. miltiorrhiza. As the growing market for S. miltiorrhiza, the enhancement of its bioactive compounds has become a research hotspot. S. miltiorrhiza exhibits a significant response to various PGRs in the production of phenolic acids and tanshinones. Here, we briefly review the biosynthesis and signal transduction of PGRs in plants. The effects and mechanisms of PGRs on bioactive compound production in S. miltiorrhiza are systematically summarized and future research is discussed. This article provides a scientific basis for further research, cultivation, and metabolic engineering in S. miltiorrhiza.

Plant growth regulators (PGRs) are chemical substances that imitate the functions of phytohormones to enhance the crop yield and the harvest process. Phenylurea-derived plant growth regulators are known for their excellent efficacy in promoting fruit growth, particularly in kiwifruit, grapes, and melons. Phenylurea derivatives represent one class of the highly efficient and versatile PGRs. Specifically, forchlorfenuron (CPPU, N-(2-chloro-4-pyridinyl)-N′-phenylurea) exhibits similar growth-regulating efficacy to cytokinins and has a significant impact on the plant growth and the crop yield. As a result, there is growing interest in exploring the incorporation of various phenylurea moieties into agrochemicals to enhance their regulatory properties on crops. This review aims to provide a comprehensive overview on representative synthetic approaches for phenylurea derived PGRs. Additionally, we provide our perspective on the future development in this active research field.

Abstract Background The process of optimizing in vitro shoot proliferation is a complicated task, as it is influenced by interactions of many factors as well as genotype. This study investigated the role of various concentrations of plant growth regulators (zeatin and gibberellic acid) in the successful in vitro shoot proliferation of three Punica granatum cultivars (‘Faroogh’, ‘Atabaki’ and ‘Shirineshahvar’). Also, the utility of five Machine Learning (ML) algorithms—Support Vector Regression (SVR), Random Forest (RF), Extreme Gradient Boosting (XGB), Ensemble Stacking Regression (ESR) and Elastic Net Multivariate Linear Regression (ENMLR)—as modeling tools were evaluated on in vitro multiplication of pomegranate. A new automatic hyperparameter optimization method named Adaptive Tree Pazen Estimator (ATPE) was developed to tune the hyperparameters. The performance of the models was evaluated and compared using statistical indicators (MAE, RMSE, RRMSE, MAPE, R and R2), while a specific Global Performance Indicator (GPI) was introduced to rank the models based on a single parameter. Moreover, Non‑dominated Sorting Genetic Algorithm‑II (NSGA‑II) was employed to optimize the selected prediction model. Results The results demonstrated that the ESR algorithm exhibited higher predictive accuracy in comparison to other ML algorithms. The ESR model was subsequently introduced for optimization by NSGA‑II. ESR-NSGA‑II revealed that the highest proliferation rate (3.47, 3.84, and 3.22), shoot length (2.74, 3.32, and 1.86 cm), leave number (18.18, 19.76, and 18.77), and explant survival (84.21%, 85.49%, and 56.39%) could be achieved with a medium containing 0.750, 0.654, and 0.705 mg/L zeatin, and 0.50, 0.329, and 0.347 mg/L gibberellic acid in the ‘Atabaki’, ‘Faroogh’, and ‘Shirineshahvar’ cultivars, respectively. Conclusions This study demonstrates that the 'Shirineshahvar' cultivar exhibited lower shoot proliferation success compared to the other cultivars. The results indicated the good performance of ESR-NSGA-II in modeling and optimizing in vitro propagation. ESR-NSGA-II can be applied as an up-to-date and reliable computational tool for future studies in plant in vitro culture.

Plant growth regulators (PGRs) are involved in multiple aspects of plant life, including plant growth, development, and response to environmental stimuli. They are also vital for the formation of secondary metabolites in various plants. Salvia miltiorrhiza is a famous herbal medicine and has been used commonly for > 2000 years in China, as well as widely used in many other countries. S. miltiorrhiza is extensively used to treat cardiovascular and cerebrovascular diseases in clinical practices and has specific merit against various diseases. Owing to its outstanding medicinal and commercial potential, S. miltiorrhiza has been extensively investigated as an ideal model system for medicinal plant biology. Tanshinones and phenolic acids are primary pharmacological constituents of S. miltiorrhiza. As the growing market for S. miltiorrhiza, the enhancement of its bioactive compounds has become a research hotspot. S. miltiorrhiza exhibits a significant response to various PGRs in the production of phenolic acids and tanshinones. Here, we briefly review the biosynthesis and signal transduction of PGRs in plants. The effects and mechanisms of PGRs on bioactive compound production in S. miltiorrhiza are systematically summarized and future research is discussed. This article provides a scientific basis for further research, cultivation, and metabolic engineering in S. miltiorrhiza. [ABSTRACT FROM AUTHOR]

Bitter pit is a disorder affecting the appearance of apples. Susceptibility is genetically controlled by both the cultivar and rootstock, with both environmental and horticultural factors affecting its severity and proportional incidence. Symptoms appear more frequently at the calyx end of the fruit and consist of circular necrotic spots, which take on a "corky" appearance visible through the peel. Bitter pit may develop before harvest, or after harvest, reducing the proportions of marketable fruit. In this review, current knowledge of the factors associated with the occurrence of bitter pit in apples is summarized and discussed along with their interactions with Ca uptake and distribution to fruit. This disorder has been previously linked with localized Ca deficiencies in fruit during its development. However, these relationships are not always clear. Even with over a century of research, the precise mechanisms involved in its development are still not fully understood. Additional factors also contribute to bitter pit development, like imbalances of mineral nutrients, low concentration of auxins, high concentration of gibberellins, changes in xylem functionality, or physiological responses to abiotic stress. Bitter pit remains a complex disorder with multiple factors contributing to its development including changes at whole plant and cellular scales. Apple growers must carefully navigate these complex interactions between genetics, environment, and management decisions to minimize bitter pit in susceptible cultivars. Accordingly, management of plant nutrition, fruit crop load, and tree vigor still stands as the most important contribution to reducing bitter pit development. Even so, there will be situations where the occurrence of bitter pit will be inevitable due to cultivar and/or abiotic stress conditions. [ABSTRACT FROM AUTHOR]

This study aimed to develop a suitable micropropagation protocol for black mulberry (Morus nigra L.), which cannot be easily clonally propagated like the other mulberry species. Clonal propagation of this species is gaining importance due to its health benefits and utilization in pharmacology. The effects of the culture media and cytokinin concentrations on the micropropagation of black mulberry were investigated. Single-axillary bud explants grown on Murashige and Skoog medium, Driver and Kuniyuki walnut medium, and Nas and Read medium (NRM) containing 0.25 mg L-1 of benzyladenine (BA) plus 0.01 mg L-1 of indole-3-butyric acid (IBA) were compared to cultures grown on NRM with thidiazuron (TDZ), meta-Topolin (mT), or BA at concentrations of 1.25, 2.5, 5.0, or 7.5 mg L-1 plus 0.01 mg L-1 of IBA. The culture medium had a significant effect on the shoot length, which was greater on the NRM (3.3 shoots per explant) compared to the other media. Shoot multiplication was similar on all of the tested media. TDZ negatively affected shoot formation and triggered rosette shoots and/or large callus formation. BA and mT promoted both shoot proliferation and elongation. Around 84% of the micro shoots rooted and the rooted shoots were successfully acclimatized to ex vitro conditions. [ABSTRACT FROM AUTHOR]

Bell pepper (Capsicum annuum L.), along with potato and tomato, is one of the three most cultivated vegetables in the world. Bell pepper is worldwide accepted due to its characteristics of color, smell, flavor, and texture. Bell pepper is also considered a nutritious food due to its vitamin and antioxidant contents. In Mexico, bell pepper production has a high value because it is grown for the international markets, particularly the United States of America. Nevertheless, the abscission of flowers and fruits is a factor that limits the yield, hinders the planning of activities, and causes a variation in the prices of peppers. Due to the importance of this process, in this work we did a bibliometric analysis and literature review of scientific advances for the understanding of the abscission process in plants, and in particular for the bell pepper. Finally, we introduce new perspectives that would help direct future research about organ abscission in plants. Likewise, the lack of research that would further clarify abscission process in the bell pepper plant is discussed. [ABSTRACT FROM AUTHOR]

Cryopreservation is a promising method for the long-term preservation of plant germplasm, especially for vegetatively propagated species like freesias. In this study, we investigate streamlining the cryopreservation process for 'Sunny Gold' Freesia, starting from effective in vitro initiation and proliferation using various plant growth regulator combinations. We also assess the impact of subculture on regrowth rates after cryopreservation. The shoot tips were successfully initiated in vitro after sterilization. The shoots were multiplied an average of three times in media containing N6-benzyladenine and kinetin. The regrowth rates of non-cryopreserved shoot tips excised from different subculture cycles did not differ significantly, with rates of 44% observed for plants from more than five subcultures and 47% for those from three subcultures. However, only the shoot tips excised from cultures subjected to three subculture cycles were able to recover after cryopreservation, with a regrowth rate of 31%. Our findings lay the groundwork for the development of an efficient cryopreservation protocol for freesias in the future. [ABSTRACT FROM AUTHOR]

Pesticides play a crucial role in agricultural production by preventing diseases and pests and ensuring food yield. However, the irrational use of pesticides can lead to numerous issues that compromise crop quality and counteract the original intentions of their application. Therefore, it is necessary to identify more effective methods to counteract pesticide stress. Here we review the impacts of herbicides, insecticides, and fungicides on plants and the measures taken to reduce pesticide residues on plants. We have found that despite the substantial differences in the mechanisms of action of the aforementioned three types of pesticides, the adverse effects they inflict on plants are similar, and at certain dosages, they can severely constrain plant growth and disrupt physiological functions. Also, most current research on using exogenous growth regulators to alleviate pesticide stress still focuses on photosynthesis, the antioxidant system, three-stage detoxification, and secondary metabolites, neglecting the search for genes that respond to pesticide stress. We believe that by combining biological protection with post-harvest treatment techniques and exploring potential genes that are responsive to pesticide stress, a better strategy for dealing with pesticide stress can be found, thereby promoting sustainable agricultural development. [ABSTRACT FROM AUTHOR]

Studies on the wheat response under late sowing (LS) and salinity stress (SS) are available, however, in rice-wheat and cotton-wheat cropping systems, wheat planting is often delayed resulting in co-occurrence of LS and SS in salt affected soils. This two-year field study was conducted to evaluate the influence of foliar application of plant growth regulators (PGRs) [thiourea (TU), salicylic acid (SA) and hydrogen peroxide (H2O2); water and no application were taken as control] on the productivity, grain quality and economic returns of timely-sown (TS) and LS wheat under normal (NC) and natural saline conditions (SS; EC 11.27 dS m− 1). Delay in sowing and planting in naturally saline soils caused a significant decrease in plant growth, grain yield, grain quality and net economic returns during both years of study. Late planting and SS caused a significant reduction in grain yield reduction by 40.58% and 34.72% (LS) and 40.66% and 42.89% (SS) compared with respective controls during 2021 and 2022, respectively. However, the influence of co-occurrence of LS and SS was more devastating than the individual stress causing 62.17% and 60.18% reduction in grain yield than the respective control during 2021 and 2022, respectively. However, the application of all PGRs improved the grain yield, grain quality and economic turnover under SS and LS stress. The order of improvement in grain yield by the application of PGRs treatments was TU > SA > H2O2. In conclusion, the application of different plant growth regulators improved economic returns, grain yield and quality attributes of late-sown wheat under saline conditions. In this regard, TU application was the most effective. [ABSTRACT FROM AUTHOR]

The convenient method for the synthesis of α‐([sydnon‐ and sydnone imin]‐4‐yl‐thio)acetylferrocenes was elaborated. A growth‐regulating activity of these ferrocene derivatives as well as their antidote activity against Metsulfuron‐Methyl (Zinger WP) herbicide was investigated in vegetation experiments on corn seedlings. The high dose‐dependent growth regulating activity of a number of the ferrocenes bearing a mesoionic heterocyclic substituent (sydnone or sydnone imine) was discovered. [ABSTRACT FROM AUTHOR]

This study aims to establish an efficient protocol for protoplast isolation, cell division, and callus induction in two carnation cultivars, Chabaud and Giant Chabaud, by examining the influence of different types of plant tissue, enzyme concentrations, incubation times, cotyledon ages, and medium compositions. Our results indicate that protoplast yield varies significantly between different plant tissues, with true leaves offering the highest yield and viability, especially under a 0.1% driselase concentration and a 6-h incubation time. We observed that increasing the driselase concentration to 1.0% significantly reduced protoplast yields in all tissues tested. In addition, the age of the cotyledons notably affected protoplast yield, with younger cotyledons providing higher yields. The Murashige and Skoog medium supplemented with 1 mg/L zeatin and 1 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) proved to be the most effective for promoting cell division and colony formation from protoplasts derived from cotyledons and true leaves. The study also found that plant growth regulators (PGRs) significantly influence callus proliferation, with differences observed between protoplast sources. [ABSTRACT FROM AUTHOR]

The foliar application of nutrients and plant growth regulators (PGRs) at critical crop growth periods can improve the yield of field crops. Hence, the present study was conducted to quantify the effects of the combined application of nutrients and PGRs (crop-specific formulation) on maize, blackgram, greengram, groundnut, cotton, sugarcane, and coconut yield. In all the crops except coconut, the treatments included (i) a foliar spray of crop-specific nutrients and PGR combinations and (ii) an unsprayed control. In coconut, the treatments included (i) the root feeding of coconut-specific nutrients and PGR combinations and (ii) an untreated control. Crop-specific nutrient and PGR formulations were sprayed, namely, Tamil Nadu Agricultural University (TNAU) maize maxim 1.5% at the tassel initiation and grain-filling stages of maize, TNAU pulse wonder 1.0% at the peak flowering stage of green gram and black gram, TNAU groundnut-rich 1.0% at the flowering and pod-filling stages of groundnut, TNAU cotton plus 1.25% at the flowering and boll development stages of cotton, and TNAU sugarcane booster 0.5% at 45 days after planting (DAP), 0.75% at 60 DAP, and 1.0% at 75 DAP of sugarcane. The results showed that the foliar application of TNAU maize maxim, TNAU pulse wonder, TNAU groundnut-rich, TNAU cotton plus and TNAU sugarcane booster and the root feeding of TNAU coconut tonic increased the yield of maize, pulses, groundnut, cotton, sugarcane, and coconut, resulting in higher economic returns. [ABSTRACT FROM AUTHOR]

Nymphoides coronata is an endangered aquatic plant species with significant medicinal and ecological importance. To preserve N. coronata from going extinct, we need to provide seedlings and efficient multiplication techniques so that it can be extensively studied. This study aimed to identify the most suitable sterilization treatment, growth medium, and substrate for the cultivation and propagation of N. coronata. Ethanol sterilization, fungicide treatment, and sterile water washing were the most important sterilization steps. A combination of 6-benzylaminopurine (6-BA) and indoleacetic acid (IAA) was the most suitable medium for bud induction and shoot proliferation. The use of α-naphthaleneacetic acid (NAA) increased the rooting rate and rooting time compared to indole-3-butyric acid (IBA). Increasing the concentration of NAA from 0.5 to 1.0 mg/L increased the rooting rate from 78 to 100% and reduced the rooting time from 7 to 5 days. The survival rate of N. coronata seedlings was 100% in a mixture of red soil and sand (1:1, w/w). As a result, the procedure mentioned above could potentially be used to safely propagate this rare species on a large scale. These findings provide valuable insights into the optimal conditions for the successful cultivation and propagation of N. coronata, which can contribute to the conservation and sustainable use of this important rare plant species. [ABSTRACT FROM AUTHOR]

In developing countries like India, rapid urbanisation was under way and the diet habits of the people have been changing day to day. Under this transformation, a section of the population is focused on nutritional security where vegetables play a major role in daily diet. Among different vegetables coloured bell pepper which is commonly known as capsicum, has importance due to its nutritional quality and market demand. The quality and productivity of coloured capsicum can be improved by choosing the best performing hybrids and exogenous application of plant growth regulators. Considering the above, the present study was conducted from November to April of 2020-21 and 2021-22 at the Protected Cultivation Unit of Centurion University of Technology and Management, Paralakhemundi, Odisha under controlled environment conditions. The experiment was laid out in factorial randomized block design consisting of two hybrids, namely, Orobelle (yellow colored) and Bomby (red colored); and eight treatments of growth regulators which were GA3 @ 25 ppm, GA3 @ 50 ppm, GA3 @ 75 ppm, GA3 @ 100 ppm, NAA @ 20 ppm, NAA @ 40 ppm, NAA @ 60 ppm and NAA @ 80 ppm. A total of 16 treatment combinations were worked out in the experiment which were replicated thrice. The results of the experiment revealed that there was no significant variation among the hybrids cultivated with respect to yield attributes, yield, quality parameters and growth attributes excluding plant height and number of leaves per plant at 60 DAS and 90 DAS. However, there was a significant impact of plant growth regulators on growth attributes, yield attributes, yield and quality parameters. The application of NAA @ 80 ppm resulted in early flowering (43.8 days after planting). Moreover, the maximum number of flowers per plant (32.5 flowers/plant), flower to fruit ratio (52.9), fruits per plant (19.5) and weight of the fruit (133.6 g) recorded in GA3 @ 100 ppm application. There was a significant interaction effect among treatment combinations in fruit yield where the highest value was recorded in Bomby hybrid with GA3 @ 100 PPM application. From the study it may be concluded that cultivation of both the hybrids can be considered as per the fruit colour and market demand along with the application of GA3 @ 100 ppm under controlled environment conditions. [ABSTRACT FROM AUTHOR]

The study focuses on Muehlenbeckia platyclada, a pharmaceutically valuable plant from the Polygonaceae family, which is scarce in India and primarily found in the southern region. Due to its pharmacological significance and limited availability, the study aims to establish a quick and reliable micropropagation protocol for its propagation and conservation by using nodal explants and also confirms the genetic identity of regenerants by using SCoT, ISSR markers for the first time. To establish the micropropagation in M. platyclada, different concentrations (0.50–4.00 mg/L) and types of PGRs like BAP, Kin, IAA, IBA, and NAA were supplemented in Murashige and Skoog (MS) media. The best shoot induction response (100%) with 6.74 ± 0.14 mean number of shoots were observed on BAP 1.50 mg/L alone. The highest mean number of multiple shoots, i.e. 16.72 ± 0.14 with 10.51 ± 0.2 cm of mean shoot length were obtained on 1.00 mg/L of BAP and 0.50 mg/L of IAA. The regenerants rooted in vitro on IBA 2.00 mg/L augmented in MS ½ strength media, which resulted in an average of 5.87 ± 0.06 mean number of roots per explant. Crucially, the regenerated plantlets showed no genetic changes when evaluated by using SCoT and ISSR markers. The biotechnological methods used in this study were able to create a micropropagation system that allows M. platyclada plants to reproduce in a way that is genetically stable. [ABSTRACT FROM AUTHOR]

Background: The process of optimizing in vitro shoot proliferation is a complicated task, as it is influenced by interactions of many factors as well as genotype. This study investigated the role of various concentrations of plant growth regulators (zeatin and gibberellic acid) in the successful in vitro shoot proliferation of three Punica granatum cultivars ('Faroogh', 'Atabaki' and 'Shirineshahvar'). Also, the utility of five Machine Learning (ML) algorithms—Support Vector Regression (SVR), Random Forest (RF), Extreme Gradient Boosting (XGB), Ensemble Stacking Regression (ESR) and Elastic Net Multivariate Linear Regression (ENMLR)—as modeling tools were evaluated on in vitro multiplication of pomegranate. A new automatic hyperparameter optimization method named Adaptive Tree Pazen Estimator (ATPE) was developed to tune the hyperparameters. The performance of the models was evaluated and compared using statistical indicators (MAE, RMSE, RRMSE, MAPE, R and R2), while a specific Global Performance Indicator (GPI) was introduced to rank the models based on a single parameter. Moreover, Non‑dominated Sorting Genetic Algorithm‑II (NSGA‑II) was employed to optimize the selected prediction model. Results: The results demonstrated that the ESR algorithm exhibited higher predictive accuracy in comparison to other ML algorithms. The ESR model was subsequently introduced for optimization by NSGA‑II. ESR-NSGA‑II revealed that the highest proliferation rate (3.47, 3.84, and 3.22), shoot length (2.74, 3.32, and 1.86 cm), leave number (18.18, 19.76, and 18.77), and explant survival (84.21%, 85.49%, and 56.39%) could be achieved with a medium containing 0.750, 0.654, and 0.705 mg/L zeatin, and 0.50, 0.329, and 0.347 mg/L gibberellic acid in the 'Atabaki', 'Faroogh', and 'Shirineshahvar' cultivars, respectively. Conclusions: This study demonstrates that the 'Shirineshahvar' cultivar exhibited lower shoot proliferation success compared to the other cultivars. The results indicated the good performance of ESR-NSGA-II in modeling and optimizing in vitro propagation. ESR-NSGA-II can be applied as an up-to-date and reliable computational tool for future studies in plant in vitro culture. [ABSTRACT FROM AUTHOR]

The damask rose (Rosa damascena Mill.) is an ornamental–medicinal plant from the Rosaceae family, and its aromatic compounds and essential oils are applied globally in the food, cosmetic, and pharmaceutical industries. Due to its economic value, this research aimed to establish a protocol for an efficient, rapid, and cost-effective method for in vitro shoot multiplication and rooting of the R. damascena 'Kashan' and 'Hervy Azerbaijan' genotypes. Nodal segments (as primary explants) were cultured on the Murashige and Skoog (MS) medium with combinations of various plant growth regulators (PGRs) such as gibberellic acid (GA3), 6-benzylaminopurine (BAP), and indole-3-butyric acid (IBA), as well as a PGR-like substance, phloroglucinol (PG), vitamins such as ascorbic acid (AA), and activated carbon in the form of active charcoal (AC). For the establishment stage, 0.1 mg·L−1 PG, 0.2 mg·L−1 GA3, and 1 mg·L−1 BAP were added to the media. Secondary explants (nodal segments containing axillary buds produced from primary explants) were obtained after 30 days of in vitro culture and transferred to the proliferation media supplemented with different concentrations of BAP (0, 0.5, 1, 1.5, 2, and 2.5 mg·L−1) and GA3 (0, 0.1, 0.2, 0.4, 0.8, and 1 mg·L−1) together with 0.1 mg·L−1 PG and 20 mg·L−1 of AA. The rooting media were augmented with different concentrations of BAP and GA3 with 0.1 mg·L−1 of IBA, PG and 20 mg·L−1 of AA and AC. The results showed that the highest regeneration coefficient (4.29 and 4.28) and the largest number of leaves (23.33–24.33) were obtained in the explants grown on the medium supplemented with 2 mg·L−1 BAP and 0.4 mg·L−1 GA3 for the 'Kashan' and 'Hervy Azerbaijan' genotypes, respectively. Likewise, this PGR combination provided the shortest time until bud break (approximately 6.5 days) and root emergence (approximately 10 days) in both genotypes. The highest number of shoots (4.78 per explant) and roots (3.96) was achieved in this medium in the 'Kashan' rose. Stem and root lengths, as well as stem and root fresh and dry weights, were also analyzed. In most measured traits, the lowest values were found in the PGRs-free control medium. Rooted plantlets were transferred to pots filled with perlite and peat moss in a 2:1 proportion and were acclimatized to ambient greenhouse conditions with a mean 90.12% survival rate. This research contributes significantly to our understanding of Damask rose propagation and has practical implications for the cosmetic and ornamental plant industries. By offering insights into the manipulation of regeneration processes, our study opens up new possibilities for the effective production of high-quality plant material. [ABSTRACT FROM AUTHOR]

This study was aimed to establish an efficient micropropagation protocol for three popular kenaf (Hibiscus cannabinus L.) cultivars (V36, HF992 and KB6) using different types of plant growth regulators (PGR’s) on Murashige and Skoog medium (MS). The shoot tip, cotyledon and hypocotyl isolated from 2 weeks old seedlings were used as explants. MS medium fortified with different types and concentrations of cytokinins and auxin were evaluated for establishment callus formation, shoot multiplication and rooting. Among different PGR’s used, 5.0 mg/l 2iP + 0.1 mg/l NAA was the best concentration for direct shoot regeneration from cotyledon with shooting percentage of 55% in HF992 cultivar. In multiple shoot induction experiment, 1.0 mg/l TDZ + 0.1 mg/l NAA mg/l concentration has induced the highest (10.4) shoots/explant. Moreover, indirect shoot regeneration was established from callus which was induced from cotyledon, maximum callus induction percentage (88.75%) was recorded on 0.5 mg/l TDZ and 1.0 mg/l NAA in V36 variety. While, for shoot elongation and rooting, MS media half strength supplemented with 1.0 mg/l kinetin + 1.0 mg/l IBA was found to be an optimum concentration. [ABSTRACT FROM AUTHOR]

Punica granatum belongs to the Lythraceae family is one of the most important subtropical fruits native to Iran. Although the production of fruit has increased recently, there is still a gap between demand and supply. Improper handling, transportation, packaging and storage, mechanical damage, and susceptibility to chilling injury and its related physiological disorders during long-term storage are the most important causes of pomegranate postharvest losses. Fruit quality is lost with visible symptoms such as weight loss, shriveling, husk scald, fungal rot, aril color degradation, and off-flavor during long-term storage. Preserving the quality is the most important goal of the postharvest physiology industry. To minimize both qualitative and quantitative postharvest losses, it is crucial to apply appropriate knowledge and technologies during both the harvest and postharvest stages of pomegranate production. This helps to maintain the quality and shelf life of the fruit. This paper reviewed recent studies that used simple, eco-friendly, synthetic and organic plant growth regulator treatments in underdeveloped and developing countries, including proper packaging according to consumer demand and safe preservatives application, which significantly reduces postharvest losses and improves overall quality of pomegranate fruit and arils. [ABSTRACT FROM AUTHOR]

Artemisia alba Turra is an essential oil bearing plant, with Euro-Mediterranean and Southeastern European distribution. One of the distinctive characteristics of its essential oil is the variability of its terpenoid profile due to environmental, genetic and other factors. In the present work, tissue culture experiment has provided a model system of in vitro morphogenesis alteration. Auxin and cytokinin treatments were applied alone or in different combinations, leading to the development of directly rooting and root suppressed in vitro plantlets. Direct in vitro rooting was definitely related to obtaining biomass richest in flavonoid compounds (irrespectively of the PGR combination leading to obtaining this morphotype). The directly rooting morphotype was also distinguished by the highest flavones/flavonoles ratio as compared with the in situ and the rest of the in vitro samples. Underground parts of in vitro samples were shown to be significantly richer in caffeoylquinic acids as compared with aerial parts. An elevation of DCQA/CQA ratios in PGR treated plants as compared with the non-treated control could be estimated as an indication of stimulation of the esterification process with the purpose of coping with the stress of the impairment of the physiological state of normal shoot-to-root tissue formation. It was shown that in vitro morphogenesis moderation could be applied as a simple and reproducible protocol to alter polyphenolics production in tissue cultures of this plant species.Key message: in vitro culture system of Artemisia alba Turra allowed for its morphogenesis modification. Changes in root system development and callusogenesis were related to targeted alterations of flavones/flavonols ratios and esterification degree of caffeoylquinic acids. [ABSTRACT FROM AUTHOR]

The phytohormone auxin triggers root growth inhibition within seconds via a non-transcriptional pathway. Among members of the TIR1/AFB auxin receptor family, AFB1 has a primary role in this rapid response. However, the unique features that confer this specific function have not been identified. Here we show that the N-terminal region of AFB1, including the F-box domain and residues that contribute to auxin binding, is essential and sufficient for its specific role in the rapid response. Substitution of the N-terminal region of AFB1 with that of TIR1 disrupts its distinct cytoplasm-enriched localization and activity in rapid root growth inhibition by auxin. Importantly, the N-terminal region of AFB1 is indispensable for auxin-triggered calcium influx, which is a prerequisite for rapid root growth inhibition. Furthermore, AFB1 negatively regulates lateral root formation and transcription of auxin-induced genes, suggesting that it plays an inhibitory role in canonical auxin signaling. These results suggest that AFB1 may buffer the transcriptional auxin response, whereas it regulates rapid changes in cell growth that contribute to root gravitropism.