Tree Genetics and Molecular Breeding 2024, Vol.14, No.3, 144-154 http://genbreedpublisher.com/index.php/tgmb 150 shown to enhance both biomass production and salt tolerance through mechanisms such as ion homeostasis and reactive oxygen species (ROS) scavenging, making it another valuable target for genetic improvement (Gao et al., 2022). The NAC13 gene also plays a crucial role in salt stress response, with overexpression leading to enhanced salt tolerance in transgenic poplar (Zhang et al., 2019a). These genetic insights can be leveraged to develop new poplar varieties that are better suited to saline environments, thereby expanding the range of habitats where poplar can be cultivated. 7.2 Impact of improved salt tolerance on poplar's ecological and economic value Enhancing the salt tolerance of poplar species has significant ecological and economic implications. Ecologically, salt-tolerant poplars can be planted in saline soils, which are often unsuitable for other crops, thereby contributing to land reclamation and ecosystem restoration efforts. For example, the overexpression of the AhDREB transcription factor in Populus tomentosa has been shown to confer salt tolerance without growth reduction, making it a promising candidate for such applications (Guo et al., 2019). Economically, salt-tolerant poplars can improve biomass production in saline environments, as demonstrated by the PtGSTF1 gene, which enhances both growth and salt tolerance (Gao et al., 2022). This dual benefit can lead to increased wood and biomass yields, providing a sustainable source of raw materials for various industries, including bioenergy, paper, and timber. 7.3 Strategies for the conservation of salt-tolerant poplar genotypes Conserving salt-tolerant poplar genotypes is essential for maintaining genetic diversity and ensuring the long-term success of breeding programs. One strategy involves the establishment of germplasm banks that store seeds or tissue samples of salt-tolerant varieties, such as those identified through transcriptome and genome-wide association studies (Sun et al., 2018; Ge et al., 2022). Additionally, in situ conservation efforts, such as planting salt-tolerant poplars in their natural habitats, can help preserve these valuable genotypes. The use of molecular markers to identify and select for salt tolerance traits, as demonstrated in studies on cotton and rice, can also be applied to poplar breeding programs to ensure the propagation of salt-tolerant genotypes (Sun et al., 2018; Geng et al., 2023). By combining these strategies, we can safeguard the genetic resources necessary for future breeding efforts and the continued adaptation of poplar species to changing environmental conditions. 8 Integrating Genomic Insights into Forestry Practices 8.1 Practical applications of genomic research in forestry Genomic research has significantly advanced our understanding of the genetic basis of traits such as salt tolerance in poplars, which are crucial for forestry practices. For instance, the downregulation of the PagSAP1 gene in hybrid poplar (Populus alba × P. glandulosa) has been shown to enhance salt tolerance by maintaining cellular ionic homeostasis, making these genetically modified trees more suitable for planting in marginal lands (Yoon et al., 2018). Similarly, the overexpression of the PeERF1 gene in Populus alba × Populus glandulosa has demonstrated improved growth and physiological characteristics under salt stress, highlighting the potential of transcriptome analysis in identifying key regulatory factors for stress resistance (Ge et al., 2022). Additionally, the PtGSTF1 gene fromP. trichocarpa has been found to improve both biomass production and salt tolerance through the regulation of xylem cell proliferation, ion homeostasis, and reactive oxygen species scavenging (Gao et al., 2022). These findings underscore the practical applications of genomic research in developing poplar varieties that can thrive in challenging environmental conditions. 8.2 Role of salt tolerance research in sustainable forest and land management Salt tolerance research plays a pivotal role in sustainable forest and land management by enabling the cultivation of trees in saline soils, which are often unsuitable for traditional forestry. For example, the overexpression of the NAC13 gene in poplar has been shown to significantly enhance salt tolerance, making these transgenic plants more resilient to abiotic stress (Zhang et al., 2019a). The introduction of the NsNHX1 gene from the halophytic shrub Nitraria sibirica into poplar has also resulted in improved salt tolerance and root development, further supporting the use of genetically modified trees in saline environments (Geng et al., 2020). Moreover, the PeWRKY31 gene from Populus × euramericana has been found to enhance both salt and insect resistance in transgenic tobacco, indicating its potential for producing stress-resistant poplars (Yu et al., 2021). These
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