Forest trees have several pivotal roles, such as maintaining ecology, climate regulation, providing raw materials for the construction of buildings, greening roads, and being an energy source (Trumbore et al., 2015). Among these forest trees, poplar (Populus spp.) (known as ‘the people’s tree’) is one of the most widespread trees in the world (Xi et al., 2021; Yevtushenko and Misra, 2019). The poplars are essential for maintaining the world’s ecological balance and socio-economic wellbeing (Häggman et al., 2013). The first use of the poplar cultivar started in 1700–1720 when Populus nigra ‘Italica’ (P. nigra, Lombardy nigra) was used in Italy, Europe and North America. There was a rapidly increased demand for poplar plants after World War II when Europe was devastated by the lack of readily available wood for construction and fuel. Consequently, the domestication and cultivation of the genus poplar started in Europe by introducing eastern cottonwood (Populous deltoides) and followed by hybrids black poplar (P. nigra) (a hybrid of P. ×canadensis) for fulfilling the increased demands for woods (Stanton et al., 2009).

Poplar trees (family Salicaceae) are tall, deciduous, dioecious, paleopolyploids, or ancient polyploids, naturally diverse, fast-growing and widely distributed globally (Lubrano, 1992), especially in temperate, sub-temperate and sub-tropical regions of Northern hemisphere and in tropical Africa also (Tuskan et al., 2006; Guleria et al., 2022). These poplars, except aspens and Asian mountain balsam poplars, grow widely in several regions like hot-arid and desert-like regions of central Asia and Africa, alpine forests in Europe and North America, as well as riparian zones like river banks and flood plains (Guleria et al., 2022). Poplars are the dominant species in these habitats for tolerating and sustaining in the complete flood. China, Turkey, France, India and the Po River plain of Italy are the largest poplar farming areas for worldwide wood supply, whereas Italy, Spain, France and Hungary provide a landscape of 0.5 out of 0.61 million hectares for poplar farming only. Poplars shape global forests and woodlands in their natural habitats. Besides being domesticated as an agroforestry tree, they provide timber, fuel wood, plywood, industrial roundwood, sports materials, pallets, paper pulp for the paper industry and fodder (Kollert et al., 2014). In addition, Populus species are cultivated as energy crops/biofuel (ethanol) in Europe (England and Italy) for carbon sequestration and sustainable bioenergy production in USA because of its high biomass production in a relatively short time (Dou et al., 2017). They are also used in the phytoremediation of toxins, e.g., heavy metals (Cd, Pb, As, and Hg) from contaminated soils, indicating ozone pollution as a bio-indicator, rehabilitation of fragile ecosystems and restoration of forest landscapes (Alahabadi et al., 2017).

Poplar (Genus: Populus) comprises 32–40 species based on taxonomic and morphological traits (Cronk, 2005; Douglas, 2017). There is a record of a total 582 Populus species, with more than 100 species names recognized worldwide. The higher number of species is due to the presence of naturally occurring hybrids (The Plant List, 2013). According to Eckenwalder (1996), the genus Populus is classified into six groups including the cottonwoods (Aigeiros), aspens (Populus), balsam poplars (Tacamahaca), large-leaf or swamp poplars (Leucoides) and (Abaso) and Afro-Asian poplars (Turanga), and but the Flora of China recognized 71 species from five sections (except Abaso) (Park et al., 2004; Table 1). Species boundaries among poplars are sometimes variable as intrasectional and intersectional hybridization occurs among them. However, this has not been supported by molecular evidence. Hence relationships between these sections are reported to be controversial (Wang et al., 2014; Liu et al., 2017; Zhang et al., 2018). During 1950s, poplar was introduced in India from the United States of America. Since then, P. deltioides, have been cultivated in India and cover an area of 270,000 ha in India, according to the report of the Indian Council of Forestry Research and Education (ICFRE, 2016; Eqbal and Ansari, 2024). Several researches have proved that the genus populus is a rich source of active metabolites, like phenolic compounds, terpenoids, and flavonoids in different parts like stems, buds, leaves and bark (Guleria et al., 2022). These poplar trees have been used to cure various ailments and have several pharmacological properties such as antioxidants, antimicrobials, anticancer, and anti-inflammatory (Guleria et al., 2022).

Poplar was the first woody perennial tree used as a model/experimental tree species among forest trees worldwide for understanding several aspects such as taxonomy, genetics, evolution and the genomics of wood formation for decades because of their small genome size, clonal propagation, fast growth, easy transformation, and long-life cycle (Taylor, 2002). In addition, poplar genome has been completely sequenced after Arabidopsis and rice. Moreover, it is the most advanced genomics resource of any forest tree, having reference genomes for several tree species. The black cottonwood (P. trichocarpa) was the first forest tree whose genome was sequenced entirely, and currently, there are massive genomic resources available for other poplar species. Interestingly, P. tomentosa and P. euphratica genomes have been extensively studied, while others have been ignored. All Populus species contain 19 haploid genomes (Shi et al., 2024). However, massive rearrangement and diploidization of the whole genome of poplar have been reported. The arabidopsis-poplar genome comparative model approach has been used efficiently in many cases (Rottmann et al., 2000; Jansson and Douglas, 2007). The genus Populus is an excellent model for studying the molecular genetic mechanisms involved in pathogen defense responses in several forest trees. The availability of Populus genome sequences enhances the efficiency of the substantial molecular tool kit that already exists for Populus species, including expressed sequence tags (ESTs) collection and microarrays for transcriptome. In addition, these tools can be applied with valuable pedigrees and genetic maps developed for Populus breeding for decades (Sterky et al., 1998; Frewen et al., 2000; Hertzberg et al., 2001; Cervera et al., 2001; Bhalerao, 2003; Andersson Gunnerås et al., 2006). Such pedigrees have been proven useful and efficient in revealing Populus loci responsible for conferring resistance to fungal pathogens attacks (Goué-Mourier et al., 1996). Poplar cultivation is severely affected by several ranges of pest insects and pathogens such as fungi, bacteria, and viruses, resulting in reduced growth and quantity and quality of wood. These biotic stresses comprise the complex interactions between hosts, pests, pathogens, and environmental factors, negatively affecting the poplar population (Seserman, 2018). The efficiency of traditional methods for protecting poplar farming from attack of pests and pathogens is hindered by factors like climatic instability, global warming, flood, drought, high temperatures and humidity. Consequently, new biotechnological approaches like genetic transformation and genome editing are required to overcome these limitations of traditional breeding. These tools are utilized to increase the quality and yield of wood and improve pest and pathogen resistance in forest trees, including poplar (Li P. et al., 2024; Li Y. et al., 2024; Li Z. et al., 2024). This paper primarily summarized the details of pest and pathogen attacks that cause diseases in poplar trees. We also examined the mechanism of infection, transmission route, the role of lignin in protecting poplar against pests and pathogens and the mode of control of diseases in poplar. Here, we also emphasized conventional breeding and its limitation for poplar plantations on a large scale. The application of different tools of genetic transformation and genome editing for developing transgenic poplar resistant to pests and pathogens was discussed in detail. Finally, we summarize the regeneration of transgenic poplar trees that have been modified by incorporating defense genes, such as those conferring pest and pathogen resistance.

Poplars are frequently impacted by infestations of insect pests such as mites, aphids, and caterpillars, as well as bacterial, viral, and fungal infections. These pests and pathogens target all parts of the tree, damaging buds and leaves, inducing gall formation, sucking sap, altering bark structure, and boring into shoots and roots, which facilitates the transmission of plant diseases. Over time, these attacks can lead to complete defoliation, reduced tree growth, and even tree death. As a result, affected poplars become unsuitable for various uses, including furniture production, biofuel generation, and veneering (Charles et al., 2018).

The vast diversity of insect pests and pathogens poses significant challenges to forest trees, severely impacting their health and productivity. These threats are particularly serious for poplar plantations worldwide. Climate change also plays a crucial role in altering the occurrence and spread of native and invasive insect outbreaks. Insects typically target susceptible trees for feeding or establishing habitats, further exacerbating the problem. These insects attack and affect all tree parts like shoot, xylem, phloem leaves, flowers, barks, and roots (Balla et al., 2021). In addition, most insects are generally introduced into a non-native area other than their native range and spread rapidly across the country. Imported alive plants and wood materials can act as carriers for introducing many pests (Dara et al., 2019). Fungi, the most common disease agent of poplar trees, have several invasion mechanisms and an array of virulent factors. In root rot disease, rhizomorphs (clusters of intertwining fungal hyphae) and secondary metabolites play a crucial role in infection. The rhizomorphs aggregate around the tree roots, feeding on the host tissues, and can persist in the dead tissues of infected plants for extended periods. This disease is marked by root decay, premature defoliation, wilting, and the production of dwarf fruits and leaves (Balla et al., 2021). Warmer winters, due to climate change, have increased the frequency of sporulation and the rate of fungal infections. Notably, poplar’s defense mechanisms vary depending on the type of fungus involved. Rust diseases caused by the Melampsora spp. are the most common diseases in forest trees, such as poplar. Cankers are mainly caused by attacks of fungal pathogens which affect tree branches, shoots, and twigs. It has been noticed that canker-related diseases occur because of functional failure of the cambium and phloem, carbon starvation, and hydraulic failure. For instance, the fungus inoculations Botryosphaeria disease in poplar (P. alba var. pyramidalis = Populus bolleana) arrested the regeneration of callus and phloem and decreased the rate of photosynthesis and transpiration, as well as arrested the opening of the stomatal aperture and disrupted electron transport (Xing et al., 2022). Bacteria affect plants by forming colonies on their surface or within their tissues. Unlike fungi, they cannot penetrate host cells directly. Instead, they typically enter through natural openings like stomata or through wounded areas. Once inside, these bacteria secrete extracellular enzymes that break down host cells, allowing them to colonize plant tissues. Additionally, they produce polysaccharides that clog the plant’s vascular system, reducing water transport through the xylem. Beetles and leafhoppers can also act as vectors, carrying pathogens and transmitting diseases to plants. Bacterial infections often manifest through symptoms such as spots, cankers, burns, tissue rot, and hormonal imbalances, which can lead to excessive root branching and leaf epinasty (Chatterjee et al., 2008). Certain bacteria, like Agrobacterium tumefaciens and Agrobacterium rhizogenes, inject their plasmids into plant host cells through wounded areas, integrating them into the host genome. This results in tumor gall diseases and the production of hairy roots, respectively (Sharan et al., 2019). Viral pathogens are widespread in plant ecosystems, serving two roles: as agents of plant diseases and as natural enemies of pests and tree pathogens, offering indirect protection to trees. Viral infections often cause significant tissue damage and can lead to symptoms like yellowing, chlorotic lesions, necrotic spots, and ring spots on plant parts. Some stable viruses, such as tobacco mosaic virus, do not require vectors to spread, while other viruses rely on vectors, such as aphids, mites, leafhoppers, fungi, beetles and nematodes, soil, water, other plants and debris for transmission (Balla et al., 2021). Smith and Campbell (2004) reported that the poplar mosaic virus (PopMV) infection and spread depend on the poplar genotypes.

Insects are typically controlled by the release of toxic phytochemicals from plants, which either inhibit pest growth or kill the insects (Fernandez-Conradi et al., 2021). To defend against pathogen attacks, poplars utilize two types of defense mechanisms: induced and constitutive defenses. Induced defenses are activated in response to external stimuli and involve complex processes, while constitutive defenses, the first line of defense, involve non-host resistance through physical barriers and the accumulation of phytochemicals in the plant (Alkan and Fortes, 2015; Zeng et al., 2023). Induced resistance can be further classified into locally induced resistance and systemic induced resistance (SIR). SIR provides broad-spectrum, long-lasting protection against secondary infections. The exogenous application of signal molecules that trigger these defenses can enhance plant immunity and help manage pest populations (Balla et al., 2021). Some observations demonstrate that signal molecules such as salicylic acid (SA) and methyl jasmonate (MeJA) are involved in local and systemic defense responses. Recent research proved that both SA and MeJA pathways are induced in leaves of poplar upon infection with the fungus M. larici-populina proving that both hormone pathways are essential for defense response (Ullah et al., 2019; Chen et al., 2021). Upon fungus attack, the poplar trees activates constitutive defenses involving several processes such as recognition of the fungus by receptor proteins and resistance (R) proteins (PR) resulting into pattern-triggered immunity (PTI) (receptors of plant membranes recognize molecular patterns (PAMPs) of pathogens) and effector-triggered immunity (ETI) (intracellular receptors, (a nucleotide-binding leucine-rich repeat (NLR) class recognize effectors released by pests and pathogens) as well as noncoding RNA (ncRNA)-mediated defense (non-coding RNA having more than 200 nucleotides in length with having role in plant growth and development, and stress responses), initiation of hormone signaling network pathways (mitogen-activated protein kinase (MAPK) cascades and calcium-dependent protein kinase (CDPK) involved in plant growth and development and stress response), activation of defense-related genes and transcription factors (TFs) involved in controlling gene expression by binding DNA elements at 5′ non-coding regions (promoters) of desired genes and modulating transcription rate) and accumulation of phytoconstituents (De Kesel et al., 2021; Zeng et al., 2023). In addition, the pathogen-associated protein 1 (PR1) gets activated as a plant response to abiotic and biotic stresses. Total 17 PtPR1 genes were found in Populus trichocarpa (Wang P. et al., 2023; Wang S. et al., 2023). A total of 1888 lncRNAs and 52,810 mRNAs were recognized in poplar coma (Song et al., 2024). The 30 CDPK genes and 20 closely related kinase genes were identified in Populous spp. (Zuo et al., 2013), The 11 MAPKKs (PtMKKs) and 21 MAPKs (PtMPKs) were identified in the Populus trichocarpa (Hamel, 2006). A total of 104 WRKYs (TFs) have been identified in poplar (He et al., 2012). Recently, the integrated transcriptomic and transgenic analyses were applied to understand mechanisms of poplar resistance against Alternaria alternata attack (Wang W. et al., 2022; Wang Y. et al., 2022).

The most effective method for preventing leaf diseases caused by pests, fungi, bacteria, and viruses is selecting and planting pathogen-resistant poplar clones. Another approach involves using fungicides, such as copper- and carbamide-based treatments, to prevent infections. Fungal diseases can also be managed by maintaining proper spacing between poplars, reducing weed competition, and optimizing plant density, as high relative humidity contributes to disease development. Infected leaves, roots, stems, and branches should be pruned, particularly during the dormant season, to minimize pest and pathogen attacks. Additionally, poplars should be planted in appropriate soil conditions within nurseries to promote healthy growth. Additionally, the soil from infected areas must not be used and moved with equipment (Kebert et al., 2022). Proteomic and genomic technologies offer valuable tools for precisely identifying and characterizing bacterial infections by analyzing their genetic and protein markers (Zubair et al., 2022). Recent studies have shown that lactic acid bacteria (LAB) can effectively combat plant pathogens due to their high biosecurity and ability to promote plant growth (Jaffar et al., 2023). Quorum sensing (QS) molecules, such as 3-OH PAME, regulate the virulence genes in bacteria and fungi, making the identification and development of QS-quenching genes and enzymes promising for disease control (Wang P. et al., 2023; Wang S. et al., 2023). Additionally, eucalyptus oil, known for its antibacterial properties and ability to stimulate plant defense mechanisms, has been shown to reduce plant diseases and could be used to protect poplar in the future (Montesinos et al., 2023). A few genes have been reported whose expression can impart disease resistance in poplar trees. For example, the overexpression of PdbLOX2 was able to induce the resistance in P. davidiana × P. bollena against A. alternata attack, while silencing this gene increased the susceptibility of the poplar tree to A. alternata infection (Huang et al., 2022). Furthermore, the study reported that PtoMYB142 can regulate transcription of wax biosynthesis genes [fatty acid hydroxylase (CER4) and 3-ketoacyl CoA synthase (KCS6)] mediating adaption of poplars against drought conditions were highly expressed upon infection with fungal pathogens (Song et al., 2022). In addition, lignin has a vital role in protecting poplar from pest and pathogen attacks. It is a primary three-dimensional phenolic biopolymer of the secondary cell wall in vascular plants (Ma et al., 2024). It imparts strength and imperviousness to cell walls, mediating long-distance water transport in vascular tissues. In addition, it acts as a barrier to the spread of invading pathogens as it is non-degradable to pathogens, thereby preventing their penetration into the plant cell wall and the supply of water and nutrients from plant cells to pathogens. It is noticed that the gene expression of lignin increased with higher lignin content upon pathogen infection. The genes (phenylalanine ammonia lyase (PAL), HCT4-Coumarate: coenzyme A ligase (4CL), cinnamate 4-hydroxylase (C4H), cinnamoyl-CoA reductase (CCR), cinnamyl alcohol dehydrogenase (CAD) and hydroxycinnamoyl transferase) are involved in lignin biosynthesis and highly expressed during fungal infection leading to increase in lignin content (Lee et al., 2019; Zeng et al., 2023; Ma et al., 2024; Riseh et al., 2024). Hence, regulating the lignin biosynthesis pathway may be critical for improving poplar resistance against pathogen attacks (Polle et al., 2013). It is reported that the higher expression of Pto4CL1 of P. tomentosa increased the lignin content from 33.11 to 46.65%, leading to the decreased formation of cellulose, hemicellulose, and pectin (Hu et al., 2019). RNAi technology was used to down-regulate the expression of 4CL gene to modify lignin biosynthesis in P. tremula (Kovalitskaya et al., 2016). A significant 30% reduction in lignin content has been observed in poplars due to the downregulation of cinnamate 4-hydroxylase (C4H) genes (Bjurhager et al., 2010). Similarly, the downregulation of CAD genes in Populus tremula × Populus alba led to reduced lignin levels (Özparpucu et al., 2017). Dirigent (DIR) proteins have also been identified as crucial players in lignin biosynthesis. Li et al. (2022) reported that the overexpression of PtDIR11 in poplars enhanced lignin biosynthesis, thereby increasing the trees’ resistance to Septotis populiperda. Hence, gene editing can be utilized to regulate the expression of these genes to enhance lignin biosynthesis, which confers pest and pathogen resistance in poplar trees.

The recent global temperature, drought, humidity and climate instability render poplar plants vulnerable to pests and pathogens, severely affecting wood quality and quantity (Gullino et al., 2022). Plants have physical and physiological barriers against microbial pathogens, preventing their access to plants (Kumudini et al., 2018). Plants produce antimicrobial peptides and other molecules that cause detoxification and the inhibition of virulence factors (Silva et al., 2016). Moreover, plants also apply RNA interference (RNAi), which detects invading viruses and cleaves the RNAs of viruses (Bocos-Asenjo et al., 2022). However, these pathogens have evolved to cope with the defense systems of their plant cells by secreting cell-wall degrading enzymes, which gain access for molecules into plant cytoplasm, inhibiting host defenses and promoting susceptibility of plants toward pathogens (Kaur et al., 2022). Some viral pathogens are also reported to attack and silence the host RNAi system, promoting viral pathogenicity (Leonetti et al., 2021). The increased demand for wood and its sustainability requires approaches to improve efficient production even under environmental constraints and minimize the threats due to pests affecting wood properties for industrial purposes (Polle et al., 2013). However, controlling pests and pathogens with chemicals is increasingly considered unsafe due to their high toxicity, environmental accumulation, and harmful impacts on beneficial insects, non-target organisms, and humans (Ahmad et al., 2024). The commonly adopted traditional methods for the protection of plants from attack of poplar pests and pathogens are the use of resistant clones that have good adaptability to different soil (salinity, calcium level and pH), drought and climatic conditions coupled with the adoption of proper cultivation practices (i.e., fertilization, low plant density and irrigation) (Biselli et al., 2022). Enormous progress has been made in enhancing traits such as plant growth rate, pest and pathogen resistance, and environmental adaptations in poplar plantations by applying conventional breeding practices (Ye et al., 2011). However, these traditional methods are time-consuming because of their long-life span, costly land demand, and high labor costs. In addition, because of the heterozygosity of most Populus genotypes and inbreeding depression, it is difficult to estimate the genetic control of particular traits (Ye et al., 2011). Genetic engineering and molecular breeding methods for developing transgenic poplar plants can address the limitations of traditional breeding, such as the challenges of distant hybridisation, the complexity of cultivation, and issues with interspecific hybridisation (Begna, 2021).

These tools have enormous potential to improve two or more traits simultaneously by introducing desired exogenous genes of donor plant or non-plant origin into a particular plant genome, enabling the improvement of poplar against pests and pathogens, herbicide resistance, abiotic stress, wood properties, flowering regulation and phytoremediation (Thomas, 2022).

Genetic transformation has been widely employed in research on various forest trees. This process involves introducing exogenous genes into tree cells, thereby altering their genetic traits (Li et al., 2023). Poplar trees were among the first forest trees used successfully for genetic engineering for gene research (Ye et al., 2011). For more than 20 years, several progress has been made in Populus transformation. The most widely used transgenic tools involve vector-mediated transformation, such as Agrobacterium tumefaciens-mediated and A. rhizogenes mediated and non-vector mediated transformation (Gene gun-mediated, pollen tube pathway, and protoplast transformation methods). The Genome editing method is an advanced approach for adding, deleting, or modifying genes within the specific genome (Li et al., 2023). Mobile genome editing techniques, such as clustered regularly interspaced short palindromic repeats (CRISPR)-associated (CRISPR-Cas) systems, RNA interference (RNAi), and nanoparticle-meditated gene transformation have been recently applied to improve poplar tree (Yin et al., 2021; Figure 1). Among these methods, Agrobacterium-mediated and gene gun-mediated transformations are the most widely used techniques for forest trees (Lv et al., 2020).

An efficient regeneration system is crucial for successful genetic transformation, as it enables the development of transgenic plants from a single cell carrying the desired genes. However, genetic transformation and regeneration remain significant challenges in many forest trees, including poplar. Various plant regeneration methods have been developed for poplars (Thakur et al., 2005; Li et al., 2017), which can be employed to produce transgenic trees with resistance to pests and diseases. In recent decades, significant research efforts have focused on creating transgenic poplars with enhanced resistance to abiotic stress and improved wood quantity and quality. There have been a few reports on regenerating transgenic poplar trees with biotic stress resistance. The established suspension cultures of P. alba x P. grandidentata cv. ‘Crandon’ were transformed with vectors A. tumefaciens carrying the maize Ac transposable element and an insect toxin gene isolated from Bacillus thuringiensis (Bt). These transgenic plants were regenerated by subculturing the transformed callus on the medium, supplemented with a growth regulator Thidiazuron (TDZ) of 0.11–27.0 μM (Howe et al., 1994). A. tumefaciens mediated genetic transformation and regeneration of hybrid poplar (P. alba x P. grandidentata) and transgenic quaking aspen from cuttings from young leaves were also readily achieved (Tsai et al., 1994). A. tumefaciens-mediated transformation of leaf explants of P. nigra L. was done with a Kunitz trypsin proteinase inhibitor (KTi3) gene for pest resistance, and regeneration of this transgenic leaf explants was successfully achieved (Confalonieri et al., 1998). The stems and petioles of transformed hybrid aspen (Populus tremula × P. alba) clones containing PtdPPO1 genes (conferring pest and pathogens resistant in plants) of in vitro plantlets were used for regeneration (Wang and Constabel, 2004). Further research is needed to establish a protocol for regenerating transgenic poplars with enhanced resistance to pests and pathogens from modified cells.

Poplars play a crucial role in supporting global ecological and socioeconomic wellbeing. The growing demand for poplar products has driven genetic engineering efforts to enhance various traits, particularly pest and disease resistance, as these trees are highly susceptible to numerous pests, fungi, and viruses. Considering the long growth cycle with low transformation tendency in forest trees, including poplar trees, it is necessary to establish a stable and efficient transformation system. Adopting pest and disease-resistant transgenic poplar plants to minimize yield loss and pesticide consumption has been successful. Many researchers have employed genetic transformation methods, including Agrobacterium tumefaciens, protoplast, gene gun, RNA interference, and miRNA-mediated transformations, to improve poplar resistance to pests and pathogens. These techniques, along with genome editing to introduce pest resistance genes and modulate lignin biosynthesis, offer promising avenues for developing transgenic poplar trees capable of withstanding pest and disease attacks, thus improving their survival rates. However, no research has been conducted on the pollen tube method, A. rhizogenes mediated and nanoparticle-mediated transformation to enhance pest/pathogen or virus resistance in Populus species. Further efforts are required to establish transgenic poplars with single/multiple genes for increasing biotic stress tolerance limits (pest/pathogens infestations) using nanoparticles, A. rhizogenes, and the pollen tube method. It will be optimal if the methods developed in poplar can be used in other forest trees to make them resistant to biotic and abiotic stresses. The use of omics technologies (i.e., genomics, transcriptomics, and proteomics), along with high-throughput screening and selection methods, accelerates the identification of successful transgenic poplar lines. Integrating big data, machine learning, and artificial intelligence (AI) into poplar breeding programs (i.e., data-driven breeding) can enhance the accuracy of predicting genetic alteration outcomes (Farooq et al., 2024), enabling more targeted and efficient transgenic strategies for trees. A key factor for success is the competence to regenerate transgenic plants from modified cells. Addressing the genotype dependency in poplar transformation is crucial for expanding the applicability of transgenic approaches. Developing “transgene-free” or non-GMO techniques, such as transient CRISPR expression, could alleviate regulatory and public concerns, facilitating the adoption of genetically improved poplar.