Xiaoyi Zhang

Cadmium (Cd) is a highly toxic non-essential heavy metal that severely impairs plant growth, compromises crop yield and quality, and threatens food safety and human health. Jasmonic acid (JA) and salicylic acid (SA) are well-characterized endogenous phytohormones that serve as central regulators in modulating plant adaptive responses to Cd stress. This review comprehensively synthesizes current knowledge on the involvement of JA and SA in regulating Cd accumulation and tolerance in plants, including their Cd-induced biosynthetic dynamics and signaling transduction pathways, as well as their functions in restricting Cd uptake and translocation, modulating chelation and sequestration, reinforcing antioxidant defense systems and protecting photosynthetic apparatus. Moreover, we analyze the antagonistic and synergistic crosstalk between JA and SA, and discuss how this interplay shapes Cd resilience in plants. Finally, the application potential of JA and SA in developing Cd-safe crops and phytoremediation in Cd-contaminated farmland is explored. This review provides a systematic analysis of the regulatory roles of JA and SA in plant responses to Cd stress, along with an in-depth discussion of their crosstalk. These insights contribute to the rational development of hormone-based breeding strategies for Cd-safe crops and the optimization of agronomic management practices.

SWEET (Sugars Will Eventually be Exported Transporter) proteins constitute a conserved family of sugar transporters that play pivotal roles in carbohydrate allocation and stress responses. In this study, we systematically identified 14 SWEET homologs in the genome of sacred lotus (Nelumbo nucifera) and validated their transport activity for both hexoses and sucrose. Subsequent analysis revealed that stress-responsive elements are the most enriched promoter sequences of NnSWEET genes. Quantitative expression profiling of the members found that NnSWEET4a was strongly upregulated under salt stress. NnSWEET4a was localized at the plasma membrane; its expression conferred salt sensitivity in both yeast and Arabidopsis thaliana. Transgenic Arabidopsis lines overexpressing NnSWEET4a exhibited substantial downregulation of the SOS3–SOS2–SOS1 signaling module and concomitant alterations in cellular sugar homeostasis. Further analysis revealed that exogenous sugar application aggravated salt sensitivity and SOS pathway inhibition in NnSWEET4a transgenic plants, and NnSWEET15-overexpressing Arabidopsis recapitulated identical phenotypic and molecular responses, including salt sensitivity and repression of SOS genes. These findings indicate that NnSWEET4a impairs salt tolerance through disruption of sugar homeostasis. The results establish a mechanistic framework for future investigations into SWEET-dependent regulation of sugar homeostasis and salt stress adaptation.