Iron is an essential element for most organisms. Both plants and microorganisms have developed different mechanisms for iron uptake, transport and storage. In the symbiosis systems, such as rhizobia–legume symbiosis and arbuscular mycorrhizal (AM) symbiosis, maintaining iron homeostasis to meet the requirements for the interaction between the host plants and the symbiotic microbes is a new challenge. This intriguing topic has drawn the attention of many botanists and microbiologists, and many discoveries have been achieved so far. In this review, we discuss the current progress on iron uptake and transport in the nodules and iron homeostasis in rhizobia–legume symbiosis. The discoveries with regard to iron uptake in AM fungi, iron uptake regulation in AM plants and interactions between iron and other nutrient elements during AM symbiosis are also summarized. At the end of this review, we propose prospects for future studies in this fascinating research area.

Rice ( Oryza sativa L.) is a staple crop. It was originally domesticated in tropical and subtropical regions, sustains nearly half of the global population and contributes approximately 20% of the world’s total dietary energy supply. However, its inherent sensitivity to low-temperature severely threatens yield stability. To meet the growing global food demand, rice cultivation is expanding to low-temperature-prone high-altitude and high-latitude regions. This expansion makes the low-temperature sensitivity problem worse. To cope with cold stress, rice has evolved a sophisticated regulatory network for cold sensing, signal transduction, and response. Recent research progress includes identifying key sensors (COLD1-RGA1, COG1-OsSERL2), characterizing secondary messengers (Ca² ⁺ , 2’,3’-cAMP, ROS) and downstream cascades (CBL-CIPK, CDPK, MAPK), elucidating core transcriptional modules (OsbHLH002/OsICE1-OsDREBs-COR) and auxiliary transcriptional factors (WRKY, MYB, NAC), uncovering critical genes involved in membrane lipid remodeling, and defining the roles of phytohormones (ABA and GA) that fine-tune cold stress responses. This review summarizes current understanding of these molecular mechanisms and highlights future directions for rice cold stress research.

Descurainia sophia L. Webb ex Prantl is used in traditional medicine globally. However, the lack of an efficient and reliable genetic transformation system has seriously limited the investigation of gene function and further utilization of D. sophia. In this study, a highly efficient, time-saving, and cost-effective Agrobacterium tumefaciens-mediated genetic transformation system has been developed in D. sophia. In this method, the transformation was accomplished by simply dipping developing D. sophia inflorescences for 45 s into an Agrobacterium suspension (OD₆₀₀ = 0.6) containing 5% sucrose and 0.03% (v/v) Silwet L-77. Treated plants were allowed to set seeds which were then plated on a selective medium with hygromycin B (HygB) to screen transformants. Additionally, the CRISPR/Cas9 genomic editing system was validated by targeting phytoene desaturase (PDS) gene using this floral dip method, and mutant plants with the expected albino phenotype could be obtained in 2.5 months. This genetic transformation and targeted editing system will be a valuable tool for routine investigation of gene function and further exploitation in D. sophia.

Polysaccharides are the major bioactive components of Polygonatum cyrtonema Hua, and their biosynthesis and accumulation are influenced by many agronomic practices. In this study, we applied integrative metabolome and transcriptome analyses to investigate the accumulation of bioactive components in one-year-old (1Y) and six-year-old (6Y) rhizomes of P. cyrtonema Hua treated with a plucking flower. The compound content analysis suggested that six-year-old treated rhizomes (T6) accumulated the highest polysaccharide content compared to that of one-year-old treated rhizomes (T1), one-year-old untreated rhizomes (C1), and six-year-old untreated rhizomes (C6). Metabolomics analysis showed that 4-O-galactopyranosylxylose, 6-O-α-l-arabinopyranosyl-d-glucopyranose, d-arabinose and d l-xylose significantly accumulated in T6 rhizomes. Carbohydrate metabolic pathways, including “glycolysis/gluconeogenesis”, “pentose and glucoronate interconversions” and “amino sugar and nucleotide sugar metabolism” were highly correlated with polysaccharide biosynthesis and accumulation. The transcriptome data indicated that UPG2, GPI, and GALE were positively upregulated in T6_vs_C6. In parallel, RHM and PEI were down-regulated in T6_vs_C6. Taken together, this study not only indicates that the candidate metabolites/metabolic pathways and genes affected by plucking flowers may influence the accumulation of polysaccharides in the rhizomes but also provides an easy and feasible agronomic practice to facilitate the accumulation of polysaccharides in the rhizomes of P. cyrtonema Hua.

Quercetin glucosides are important phytopharmaceutical metabolites in Descurainia sophia seeds, which are widely used in traditional herbal medicine. However, the key genes involved in quercetin glucoside biosynthesis in D. sophia have not been characterized. Herein, we present the telomere-to-telomere genomes of a tetraploid D. sophia, which accumulates high levels of quercetin glucoside, and a diploid D. sophia, which accumulates only trace amounts. Multiomics analyses and uridine diphosphate glucosyltransferase (UGT) enzyme assays revealed that the gene duplication and functional evolution of Dscd6AG01520, an UGT gene, led to high quercetin-3-O-β-d-glucoside and quercetin-3,7-O-β-d-diglucoside accumulation in tetraploid D. sophia seeds. Further UGT enzyme assays with the point mutations of Dscd6AG01520 showed that S213 was a critical amino acid for the enzymatic activity of Dscd6AG01520. In addition, we found that diploid D. sophia evolved from an ancestral crucifer karyotype through chromosome fusion and rearrangement. Collectively, our findings illuminate the mechanism of high quercetin glucoside accumulation in tetraploid D. sophia, clarify the origin of the diploid D. sophia genome, and provide valuable genomic resources for comparative genomics and research into polyploid evolution.