Hye-Yeon Seok ¹ Byeong-ha Lee ^2* Yong-Hwan Moon ^1,3,4*

• ¹ Institute of Systems Biology, Pusan National University, Busan, Republic of Korea
• ² Department of Life Science, Sogang University, Seoul, Republic of Korea
• ³ Department of Integrated Biological Science, Pusan National University, Busan, Republic of Korea
• ⁴ Department of Molecular Biology, Pusan National University, Busan, Republic of Korea

Li et al. (2023) examined the role of the NAC transcription factor MdNAC29 in apples, revealing its negative regulation of drought tolerance. Overexpression of MdNAC29 resulted in increased oxidative damage, reduced chlorophyll content, and downregulation of droughtresponsive genes like MdDREB2A. The interaction between MdNAC29 and F-box protein MdPP2-B10 further highlighted its regulatory role in transcriptional repression under drought conditions. This study underscores the complexity of transcription factor-mediated gene expression and provides a basis for improving drought tolerance through genetic engineering (Li et al., 2023). Xu et al. ( 2023) identified a novel catalase gene, PtCAT2, from Pinellia ternata, which enhances drought tolerance in Arabidopsis thaliana. Overexpression of PtCAT2 increased catalase activity by five-fold, leading to improveed reactive oxygen species (ROS) scavenging and a reduction in oxidative damage. This study highlights the pivotal role of ROS balance in osmotic stress responses and positions PtCAT2 as a candidate for genetic interventions in drought-sensitive crops (Xu et al., 2023). Gao et al. ( 2023) employed proteomic analysis to elucidate the drought stress responses in leaves and roots of foxtail millet (Setaria italica). The study identified significant differences, with leaves primarily altering photosynthesis-related proteins and roots modifying a greater number of proteins involved in metabolites metabolism and stress-defense during both drought and recovery phases. These findings underscore the importance of tissue-specific drought adaptations for the development of drought-stress tolerant crops (Gao et al., 2023). Piríz-Pezzutto et al. ( 2024) developed an innovative in vitro osmotic gradient system to study Arabidopsis root adaptation in natural field conditions, where roots encounter increasing osmotic potential while exploring the soil. This system revealed that roots grown under osmotic gradients sustained higher growth rates and exhibited distinct changes in the expression of certain genes compared to those subjected to uniform osmotic shock. Findings from this study emphasize the importance of mimicking field conditions to uncover mechanisms of adaptive root growth (Piríz-Pezzutto et al., 2024). Guo et al. ( 2024) explored the function of MdKAI2, a receptor for karrikins (KARs), in regulating osmotic stress resistance in apples. The study demonstrated that MdKAI2 positively regulates stress tolerance by enhancing ROS scavenging, promoting flavonoid biosynthesis, and increasing osmoregulatory substances. RNA-sequencing analysis of MdKAI2-overexpressing apple calli revealed that MdKAI2 modulates the expression of various transcription factors and genes involved in the MAPK signaling pathway. These findings open avenues for leveraging KAR-related pathways to improve tree crop resilience (Guo et al., 2024). To investigate the influence of ploidy levels on salt stress tolerance in citrus, Bonnin et al. ( 2024) conducted a comparative transcriptomic analysis of diploid and tetraploid citrus genotypes under salt stress. Tetraploid genotypes exhibited enhanced oxidative stress tolerance and differential expression of genes involved in cell wall remodeling, sugar metabolism, and antioxidant responses. This research highlights the potential of polyploidy in improving abiotic stress resilience in perennial fruit crops (Bonnin et al., 2024). These studies collectively advance our understanding of osmotic stress response mechanisms across diverse plant systems. They highlight the importance of transcription factors, enzymatic regulators, proteomic changes, and genomic adaptations in mitigating osmotic stress. Future research should prioritize integrative multi-omics approaches, field-like experimental designs, and the translation of findings into crop improvement programs (Seok et al., 2023).