Yuhong Rong

Plant basic helix-loop-helix (bHLH) transcription factors constitute one of the largest and most functionally diverse transcription factor families in plants. Through a conserved bHLH domain, they bind E-box cis-elements or dimerize with partner proteins, coupling developmental and metabolic programs to environmental cues. However, a systematic synthesis of their multilayered stress responses remains lacking. Here, we review the structural features, genome-wide distribution, and evolutionary diversification of plant bHLH transcription factors, with emphasis on their regulatory functions under low-temperature, drought, salinity, and iron-deficiency conditions. We further integrate their roles in abscisic acid, jasmonic acid, and light signaling, as well as in anthocyanin and terpenoid biosynthesis, biotic stress, and immune responses. We also discuss emerging evidence linking bHLH factors to reproductive development, particularly anther and pollen formation under heat stress. Mechanistically, we summarize the multilayered regulatory network from four perspectives: transcriptional cascades, post-translational modifications, cooperative regulation by multiple transcription factors, and growth-defense trade-offs. Finally, we highlight current gaps, including limited functional validation in non-model/specialty economic crop species, underexplored combined-stress mechanisms, and lagging breeding translation, and propose future research directions. This review provides an integrated framework for plant stress biology and outlines evidence-based perspectives for future stress-tolerant crop improvement.

Rainfall erosion significantly affects nutrient transport in plantation forests, but the internal nutrient-driven mechanism remains unclear. In this study, three types of plantation forests in the Xishuangbanna were selected to examine soil nutrient contents in erosion and deposition zones, nutrient concentration in runoff, and nutrient contents in litter, while the relationship among them was analyzed using the RDA method, aiming at exploring the internal driving mechanism of nutrient transport following erosion caused by the rainy season. The results show that, after the rainy season, the nutrient contents in the soil of all three forest types decreased in the erosion zone, with the most severe changes at the bottom of the slope. Furthermore, the C contents in litter from the three forest types decreased by 8.9% to 14.8% and the K contents decreased by 30.9% to 44.5%, while the N contents increased by 3.7% to 14.8% and the P contents increased in RF and TF but decreased in AF. Based on the RDA, the presence of 81.1% of nutrients in the runoff can be explained by changes in nutrient concentrations in the erosion zone and the nutrient content in the deposition zone. Among these, the contribution rates of D.P, D.K, and DOC were 76.9%, 17.1%, and 6%, respectively, which shows that runoff is the main factor influencing the changes in and deposition of soil nutrients on the slope. The results also attribute 47.57% of nutrients in the runoff to nutrient changes in the litter. This indicates that runoff is not the primary factor influencing nutrient changes in litter; the remaining explained variance may be related to factors such as litter quality, soil animals, microbial activity, and temperature.

Introduction: Gretchen Hagen 3 ( GH3 ) genes play important roles in auxin homeostasis, plant development, and stress responses. However, their characterization and evolutionary history in early-diverging angiosperms remain poorly understood. Methods: Here, we performed a genome-wide identification and comparative evolutionary analysis of the GH3 gene family in the early-diverging flowering plant Nymphaea colorata . Phylogenetic classification, conserved motif and gene structure analyses, promoter cis-element prediction, regulatory network inference, expression profiling, and duplication/selection analyses across 22 plant species were conducted. Results: A total of 27 GH3 genes were identified in N. colorata and classified into three conserved groups, with 23 NcGH3 genes assigned to Group 2. Promoter analysis revealed abundant hormone-related and light-responsive cis-elements in NcGH3 promoters, and regulatory network prediction suggested that Dof transcription factors may act as candidate regulators of NcGH3 genes. Expression analysis showed that most NcGH3 genes were preferentially expressed in floral organs, including petals, sepals, stamens, juvenile flowers, and carpels. Comparative analysis across 22 plant species indicated that Group 1 represents the most ancestral GH3 lineage, whereas Groups 2 and 3 emerged later during plant evolution. Group-specific expansion was observed in several species and was mainly associated with whole-genome/segmental duplication and tandem duplication events. Conclusion: These findings provide a comprehensive overview of the GH3 gene family in N. colorata and offer new insights into the evolutionary diversification and subgroup-specific expansion of GH3 genes in plants.