Triticeae Genomics and Genetics, 2025, Vol.16, No.4, 175-183 http://cropscipublisher.com/index.php/tgg 180 6.2 TF expression plasticity under abiotic stress The transcription factors in the roots show strong regulatory ability in the face of environmental changes. A transcription factor or a small gene module may play different roles at different times and locations. This "flexibility" allows them to selectively act in specific cells rather than reacting to the entire root. The same type of transcription factor may regulate different downstream genes under different stresses, depending on the type of stress and the type of root cell (Walker et al., 2017; Cai and Qian, 2024). For example, some transcription factors that regulate cytokinins (such as ARR10 and CRF6) and transcription factors related to auxin will quickly start or shut down depending on the amount of nutrients, and the structure of the root will also adjust accordingly (Ramireddy et al., 2014; Roychoudhry and Kepinski, 2021). It is precisely because these genes are expressed very flexibly that the roots can adapt well to various changing environments (Ramireddy et al., 2014). 6.3 Epigenetic and transcriptomic reprogramming in response to environmental cues When the environment deteriorates, not only the expression of transcription factors will change, but the entire root system of the plant will also undergo deeper changes. This change includes reprogramming of overall gene expression and adjustments at the epigenetic level. These changes usually involve the way chromatin is opened, the way histones are modified, and the activity of non-coding RNA. These mechanisms work together to regulate which genes should be turned on and which should be turned off according to environmental signals (Roulé et al., 2021). Through single-cell and spatial transcriptome technologies, scientists have found that these regulations are often concentrated in specific cell types or developmental stages (Walker et al., 2017; Gouran and Brady, 2024). This precise multi-level control allows roots to quickly change their structure as needed in a short period of time to cope with the challenges of the external environment. 7 Concluding Remarks Transcription factors play a key role in regulating root architecture. They receive information from the environment and developmental processes, and then regulate root growth, branching number, and nutrient absorption capacity. Transcription factor families such as ARF, NAC, MYB, and WRKY have been shown to regulate plant responses to drought, salinity, and nutrient deficiency. The gene expression networks they control determine the plasticity of the root system, that is, whether the roots can flexibly adjust to the environment. Because of this, barley and other cereal crops can adapt to various complex environments. In wheat, researchers have also discovered interactions between transcription factors and chromatin remodeling factors. This relationship makes it clearer that root development and absorption functions are actually completed by a whole set of complex regulatory mechanisms. Although research has made a lot of progress, there is still a lot of room for further efforts. We need to use gene editing tools (such as CRISPR) or overexpression systems to verify whether the candidate transcription factors in barley have any effect. At the same time, higher-resolution technologies are also needed, such as transcriptome and epigenetic analysis of different cell types, so that we can know more clearly when and where these factors work. In the future, deep learning can be used for root phenotyping, combined with multi-omics data, so that gene regulation can be linked to the actual structure of the root. It is also possible to compare different cereal plants to find out which regulatory methods are universal and which are unique to barley. Single-cell transcriptomics technology and more advanced genetic manipulation methods will speed up our search and verification of key transcription factors. Understanding the regulatory network of these transcription factors will help us transform plant roots. By precisely regulating these factors and their interacting partners, crop root structure can be optimized, making plants more resistant to water and fertilizer, and more resistant to drought, salt and disease. This is an important step for breeding. Especially in the context of increasingly obvious climate change, these advances are very important for achieving sustainable agriculture and food security with high yields, water and fertilizer savings. The discovery and study of these transcription factors in barley roots also provides new methods and directions for future breeding and agricultural improvement.
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