Journal of Plant Growth Regulation

Varshini, Kumar; Parthasarathi, Theivasigamani

doi: 10.1007/s00344-026-12274-0pmid: N/A

Horticultural crops play a significant role in meeting global food demand and nutritional security. It includes a wide variety of ornamental plants, fruits and vegetables. However, horticultural crops are vulnerable to various abiotic stresses such as drought, salinity, extreme temperatures and heavy metal toxicity. These stresses activate the production of Reactive Oxygen Species (ROS), which interrupt the crop’s physiological functions, development and yield. In the search for environmentally friendly stress management practices, melatonin, a pleiotropic molecule first discovered in animals and later in plants, has received significant attention for its role in stress mitigation. In abiotic stress condition, melatonin regulates ion homeostasis, maintains osmotic balance, stabilizes cellular membranes and improves the photosynthetic system. Moreover, melatonin interacts with various phytohormones, including auxins, abscisic acid (ABA), gibberellins, cytokinins, ethylene, jasmonic acid (JA), and salicylic acid (SA), by modifying plant responses to stress through hormonal crosstalk. Melatonin controls stress-responsive genes and transcription factors by enhancing the plant’s development at the molecular level. This review elaborates on melatonin’s biosynthesis and its roles in mitigating drought, salinity, heat, cold, and heavy metal stress in horticultural crops. It also discusses future research prospects, which include genetic engineering of melatonin biosynthetic genes, nano-formulations for targeted delivery, and multi-omics approaches to resolve regulatory networks. Future research should focus on crop-specific applications, field validation, and biotechnological innovations to study melatonin’s potential in climate-resilient horticulture.

Azimychetabi, Zeynab; Kisiala, Anna B.; Morrison, Erin N.; Farrow, Scott C.; Emery, R. J. Neil

doi: 10.1007/s00344-026-12263-3pmid: N/A

Benzylisoquinoline alkaloids (BIAs) constitute a diverse class of plant secondary metabolites showcasing a range of pharmacological activities. While the biosynthetic pathways of several BIAs have been established, the timing of BIA onset and the mechanisms regulating their biosynthesis remain poorly understood. To address this gap, we conducted a time‑course analysis measuring BIAs and multiple signaling molecules, revealing dynamic changes in key metabolite groups during the early stages of Papaver rhoeas development. The rhoeadine-type BIAs exhibited increased levels during cotyledon emergence, 4 days after imbibition. This coincided with an increase in protopine, a key intermediate in rhoeadine alkaloid production. Concurrent with the initiation of BIA production, there were changes in neurotransmitter profiles and phytohormone classes. Specifically, cytokinins (CKs), trans-zeatin riboside, trans-zeatin riboside O-glucoside, and 2-methylthio-zeatin riboside (2MeSZR) showed a strong positive correlation with the production of BIAs. Exogenous application of 2MeSZR and trans-zeatin altered BIA dynamics, with 2MeSZR causing the most pronounced enhancement of BIA production and a distinct reprogramming of various BIA branch pathways. This study provides the first detailed characterization of the timing, nature, and magnitude of CK-mediated effects on secondary metabolism, offering new insight into the onset and regulation of BIA biosynthesis. Furthermore, the observation that neurotransmitter temporal dynamics mirrored those of BIAs suggests they may play a coordinated role alongside CKs in initiating BIA production or point to a potentially integrated regulatory network in which CKs may influence both BIA biosynthesis and associated neurotransmitter pathways.Graphical Abstract[graphic not available: see fulltext]

Bege, Jonathan; Pang, Wei Quan; Wahyuni, Dwi Kusuma; Sivalingam, Elayabalan; Manickam, Sankar; Mad’ Atari, Mohamad Fadhli ; Subramaniam, Sreeramanan

doi: 10.1007/s00344-026-12287-9pmid: N/A

The red banana (Musa acuminata) is valued for its nutritional, agronomic, food science and technological uses, and therefore continues to be the subject of research aimed at sustainable utilisation. Micropropagation makes an important contribution to its production, as it enables the mass production of healthy plants with the desired characteristics within a few months. Despite extensive use of light-emitting diodes (LEDs) in banana micropropagation, there is limited integrated evidence on how specific LED spectra influence genetic stability in Musa acuminata cv. red banana. Regenerated Musa acuminata cv. red banana plantlets were established using Murashige and Skoog medium supplemented with 2 µM Thidiazuron (TDZ) under six (6) different LED spectra treatments; white (400–700 nm), blue (440 nm), red (660 nm), far-red (720 nm) mint-white (500–599 nm) and blue + red (440 nm + 660 nm). Stomatal research revealed that white LED provided the highest stomatal density, while far-red and mint-white LED provided the lowest. Blue LED increased stomatal width and length, while mint white LED produced the highest length-to-width ratio. Anatomical analysis showed that mint-white and red LEDs affected both the abaxial epidermis and adaxial hypodermis, while white, blue, blue-red, and red LEDs produced well-differentiated palisades and spongy parenchyma. Genetic stability analysis was performed on the in vitro plants of Musa acuminata cv. red banana. Twenty (20) primers of each SCoT, ISSR and DAMD molecular marker were used to assess the genetic stability of the six (6) samples of Musa acuminata cv. red banana. This study revealed that inter simple sequence repeats (ISSR) and directed amplification of minisatellite DNA (DAMD) markers (DNA primers) are sufficient in determining the polymorphism and monomorphism percentage among the samples. SCoT markers showed 92.74% monomorphism, ISSR markers showed 95.57% of monomorphism whereas DAMD markers showed 84.44% monomorphism. Polymorphism of 15.56% was the highest observed under DAMD markers. However, the combine molecular markers showed 91.12% monomorphism and a Polymorphism of 8.88%. This indicates that certain wavelengths of LEDs help to maintain genetic stability and improve morphological characteristics of micropropagated red banana plants, providing an energy-saving and cost-effective method for mass propagation with minimal somaclonal variation.

Kumar, Arun; Yadav, Pradeep Kumar; Singh, Anita

doi: 10.1007/s00344-026-12237-5pmid: N/A

Pesticides are widely used to enhance crop productivity; however, excessive application can lead to residue accumulation in edible plant parts and adversely affect growth and physiology. This study evaluated the protective role of salicylic acid (SA) in radish (Raphanus sativus) exposed to cypermethrin (CYP). The plants were foliarly pretreated with SA (100–800 µM) and subsequently exposed to CYP at recommended (150 ppm) and double (300 ppm) doses. CYP, especially at the higher dose, markedly impaired physiological and biochemical traits. SA pretreatment, particularly at 200 µM, mitigated oxidative stress by reducing H2O2, SOR, and TBARS accumulation while enhancing antioxidant activities. Improvements in chlorophyll content, stomatal traits, and photosynthetic performance were also observed. Moreover, 200 µM SA increased root fresh biomass by 41.1% and 44.4% under recommended and double CYP doses, respectively, and reduced CYP residues in roots by 36–39%, while promoting formation of less toxic metabolites, 3-phenoxybenzoic acid (3-PBA) and 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA). Metabolomic analysis revealed that SA enhanced defense-related compounds, including phenylpropanoids, oxylipins, sphingolipids, and glutathione. Under high stress, SA pretreatment triggered an emergency metabolic response to generate energy and redox power for defense, whereas under lower stress, it promoted a balanced priming state, strengthening signaling and secondary metabolism. These results demonstrate that SA can serve as a phytohormone-based strategy to mitigate pesticide toxicity, improve stress tolerance, and enhance crop quality under intensive cultivation.

Khan, Md. Mustafa; Karim, Md. Abdul; Haque, Md. Moynul; Mia, M A Baset; Barma, Naresh Chandra Deb; Rahman, Md. Mahbubur; Alasmari, Abdulrahman; Gaber, Ahmed; Hossain, Akbar

doi: 10.1007/s00344-026-12279-9pmid: N/A

Salinity severely constrains wheat productivity by disrupting biomass allocation and ionic homeostasis. Although many studies have described individual physiological responses to salinity, fewer have integrated organ-specific ion regulation with whole-plant biomass dynamics to explain why some genotypes tolerate salt better than others do. To address this gap, the present study aimed to identify the physiological mechanisms that underpin salinity tolerance by combining biomass partitioning, organ-resolved ion profiling and multivariate causal modelling. Three wheat genotypes—BAW 1147 (tolerant), BARI Gom 25 (moderately tolerant), and BARI Gom 28 (susceptible)—were evaluated under control, 5 dS m⁻¹ and 10 dS m⁻¹ salinity conditions. The plants were subsequently divided into nine organs to quantify dry weight (DW) and the organ-specific ion status of sodium (Na⁺), potassium (K⁺), calcium (Ca²⁺) and magnesium (Mg²⁺). Salinity reduced the total DW in all the genotypes, but BAW 1147 consistently retained more organ-specific biomass (roots, stems, flag leaf blades) and preserved reproductive allocation. Ion profiles in BAW 1147 revealed increased sequestration of Na⁺ in roots and structural tissues. In contrast, Na⁺ concentrations remained lower in flag leaves and grain. Moreover, K⁺, Ca²⁺ and Mg²⁺ levels were maintained across organs, resulting in superior K⁺:Na⁺ ratios in photosynthetic and reproductive tissues. Correlation analysis indicated stress-dependent strengthening of positive links among biomass traits and beneficial cations, whereas principal component analysis resolved PC₁ as a tolerance axis characterized by increased biomass; higher K⁺, Ca²⁺ and Mg²⁺ concentrations; increased K⁺:Na⁺ ratios; and decreased Na⁺ levels. Structural equation modelling (SEM) revealed K+:Na+ as the strongest positive causal determinant of shoot biomass and total biomass, with Na⁺ exerting negative effects on photosynthetic and yield tissues. Overall, this integrative approach demonstrates that wheat salinity tolerance arises from coordinated biomass buffering and strategic ion partitioning across organs. These findings provide practical physiological indicators, such as high K+:Na+, stable Ca²⁺-Mg²⁺ homeostasis and balanced root investment, that can be used to select and develop salt-resilient wheat genotypes for coastal and irrigated saline environments.

Wu, Zhimeng; Song, Kangkang; Sun, Zhongtai; Chen, Xiuzheng; Ma, Huaying; Feng, Shouqian

doi: 10.1007/s00344-026-12278-wpmid: N/A

High temperature severely inhibits anthocyanin accumulation in apple fruit, leading to poor peel coloration and reduced fruit quality. However, the molecular mechanisms linking heat signaling to anthocyanin biosynthesis remain unclear. In this study, a total of 11 phytochrome-interacting factor (PIF) genes were identified in the apple genome, and their expression patterns under high-temperature conditions were analyzed. Among them, MdPIF4 was strongly induced by heat stress and showed a close association with changes in anthocyanin accumulation. Functional analyses performed in an apple callus system demonstrated that stable overexpression of MdPIF4 significantly reduced anthocyanin content and suppressed the expression of multiple key genes involved in the anthocyanin biosynthetic pathway. Furthermore, yeast one-hybrid, electrophoretic mobility shift, and dual-luciferase reporter assays revealed that MdPIF4 directly binds to the promoter of MdF3’H and represses its transcriptional activity. These results indicate that MdPIF4 functions as a heat-responsive transcriptional repressor of anthocyanin biosynthesis in apple callus by directly targeting a core structural gene. This study provides a molecular basis for understanding temperature-dependent regulation of anthocyanin biosynthesis in apple and offers insights that may be relevant to fruit coloration under high-temperature conditions.

Jadhav, Ishwar Baban; K., Venkat Raman; Paul, Krishnayan; Baaniya, Mahi; Sarkar, Rupam; Das, Suparna; A., Subhash; Sharma, Anjali; Vijayan, Joshitha; G., Rama Prashat; Sreevathsa, Rohini; Pattanayak, Debasis

Wang, Siji ; Xu, Zikai ; Sun, Yan; Zhao, Manli; Fu, Chenxi; Li, Shuping; Cheng, Lingyun

doi: 10.1007/s00344-026-12269-xpmid: N/A

Brown algal fermentation products (BA) are promising biostimulants, but the mechanisms by which they improve phosphorus (P) availability and plant performance in P-deficient soils remain unclear. This study investigated whether BA enhances P use efficiency in maize grown in calcareous soil under contrasting P supply by altering soil P availability and aggregate structure, thereby improving root foraging, photosynthetic performance, and plant P uptake. Maize was grown under low-P (LP) and high-P (HP) conditions with or without BA application, and soil P availability, inorganic phosphate (Pi) fractions, water-stable aggregates, root traits, leaf gas exchange, biomass, and plant P uptake were assessed. BA produced clear positive effects under LP but had limited effects under HP. Under LP, BA increased Olsen-P and shifted Pi from the less labile Ca₈-P fraction toward the more labile Ca₂-P fraction, with little effect on Al-P, Fe-P, or occluded P. BA also moderately restructured water-stable aggregates in maize-planted soil, increasing the proportions of the 0.25–2.00 mm and 0.106–0.25 mm fractions. These soil changes were accompanied by greater root foraging capacity, reflected in higher total root length, specific root length, and fine-root proportion. BA also enhanced leaf gas exchange, particularly photosynthetic rate and stomatal conductance, and ultimately increased biomass and plant P uptake. Overall, BA improved P acquisition under LP through a coordinated soil–root–leaf cascade involving enhanced Pi availability, altered aggregate structure, improved root architecture, and greater photosynthetic performance. These findings provide mechanistic insight into the context-dependent efficacy of algal-derived biostimulants and support their potential to improve P use efficiency in P-limited calcareous soil.

Souguir, Dalila; Zrelli, Sonia; Hachicha, Mohamed

doi: 10.1007/s00344-026-12254-4pmid: N/A

Vicia faba is an important food legume crop that is highly sensitive to salinity, particularly during germination and early growth stages. Seed pretreatment can improve plant tolerance to salt stress, but its impact on genome stability remains unclear. The present study evaluated the effects of Hydrogen peroxide (H2O2, 5 mM), Sodium nitroprusside (SNP, 0.2 mM) and their combination (H2O2+SNP) in Vicia faba roots under moderate salinity (2.5 dS/m) and high salinity (7.5 dS/m). Pretreated seeds showed improved root growth (71–129% increases compared with salt-stressed conditions) and enhanced cell division, with the Mitotic Index (MI) rising from 5.36% in roots exposed to 7.5 dS/m salinity to 8.89–11.09% in pretreated roots. However, pretreatments did not prevent the accumulation of toxic ions (Cl− and Na+), nor did they reduce genotoxic effects, as evidenced by persistent chromosomal and nuclear aberrations and an increase in micronucleus (MCN) size, while frequency remained elevated (9.75–13.16% under pretreatments compared with 12.49% under high salinity). SNP and its combination with H₂O₂ were associated with the largest MCNs, suggesting a possible disruption of chromosome segregation, although this remains hypothetical. Pretreatments appeared to mitigate some physiological effects of salt stress, such as root growth and mitotic activity, but failed to protect genome integrity, highlighting a clear distinction between physiological tolerance and genotoxic protection. Future studies integrating biochemical assays and detailed cytogenetic scoring are needed to elucidate the mechanisms by which H₂O₂ and SNP modulate cellular and genomic responses under salinity stress.

Feng, Xin; Wang, Hailong; Wu, Bei; Jia, Xiaolin; Shen, Fei; Han, Zhenhai; Zhang, Xinzhong

doi: 10.1007/s00344-026-12289-7pmid: N/A

The vegetative phase change (VPC) is a typical epigenetic event in anthophytes. DNA methylation exerts vital functions in the modulation of plant ontogenetic and biological processes. The microRNA miR156 is established as the core regulatory hub of plant VPC and the levels of miR156 are regulated at both transcriptional, post-transcriptional, and epigenetic levels. Nevertheless, whether and how genomic DNA methylation participates in the regulation of miR156 precursor genes during the VPC remain largely ambiguous in perennial woody plants including apple (Malus domestica Borkh.). In this study, whole‑genome bisulfite sequencing and RNA‑seq were used to explore how DNA methylation influences gene expression during apple VPC. Genome‑wide CG, CHG, and CHH methylation levels were stable across developmental stages. Intergenic regions were more highly methylated than gene regions. And in gene regions all three methylation contexts were significantly higher in the adult phase (nodes 61–180 on the trunk of a tree) than in the juvenile phase (nodes 0–60). Genes upregulated in the adult phase, enriched in photosynthesis, carbohydrate/lipid metabolism, and energy pathways, were related to hypomethylation. No differential methylation was detected in miR156 precursors. However, transcription factors co‑expressed with miR156 and MdMIR156a5, including brassinosteroid biosynthesis genes and MdRVE1‑1/MdRVE1‑2 were hypermethylated in adult phase. The 5‑azacytidine treatment reduced methylation of MdRVEs and increased expression of MdMIR156a5 and miR156. Overall, 57.1% of differentially expressed genes showed a negative correlation between DNA methylation and expression. Hypermethylation of MdRVEs in the adult phase was associated with repressed expression of MdMIR156a5 and miR156.