The cellulose of the plant cell wall indirectly affects the cell shape and straw stiffness of the plant. Here, the novel brittleness mutant brittle stalk-5 (bk-5) of the maize inbred line RP125 was characterized. We found that the mutant displayed brittleness of the stalk and even the whole plant, and that the brittleness phenotype existed during the whole growth period from germination to senescence. The compressive strength was reduced, the cell wall was thinner, and the cellulose content was decreased compared to that of the wild type. Genetic analysis and map-based cloning indicated that bk-5 was controlled by a single recessive nuclear gene and that it was located in a 90.2-Kb region on chromosome 3 that covers three open reading frames (ORFs). Sequence analysis revealed a single non-synonymous missense mutation, T-to-A, in the last exon of Zm00001d043477 (B73: version 4, named BK-5) that caused the 951th amino acid to go from leucine to histidine. BK-5 encodes a cellulose synthase catalytic subunit (CesA), which is involved with cellulose synthesis. We found that BK-5 was constitutively expressed in all tissues of the germinating stage and silking stage, and highly expressed in the leaf, auricula, and root of the silking stage and the 2-cm root and bud of the germinating stage. We found that BK-5 mainly localized to the Golgi apparatus, suggesting that the protein might move to the plasma membrane with the aid of Golgi in maize. According to RNA-seq data, bk-5 had more downregulated genes than upregulated genes, and many of the downregulated genes were enzymes and transcription factors related to cellulose, hemicellulose, and lignin biosynthesis of the secondary cell wall. The other differentially expressed genes were related to metabolic and cellular processes, and were significantly enriched in hormone signal transduction, starch and sucrose metabolism, and the plant–pathogen interaction pathway. Taken together, we propose that the mutation of gene BK-5 causes the brittle stalk phenotype and provides important insights into the regulatory mechanism of cellulose biosynthesis and cell wall development in maize.

In China, soil contamination by heavy metals is a widespread issue, with substantial increases in lead(Pb), cadmium(Cd), copper(Cu), and zinc(Zn) levels observed across various regions. Particularly, the concentrations of Pb and Cd significantly exceed their natural background levels. P-ATPases, a group of proteins, utilize energy from ATP hydrolysis to support the transmembrane movement of metal ions. This group encompasses several Heavy Metal Associated Transporter (HMA) ATPases. Studies on hyperaccumulators have shown the critical role of HMAs in the movement and reduction in Zn and Cd toxicity in plant systems. This research identifies a protein encoded by the SpHMA gene from Sedum plumbizincicola, a species noted for aiding Zn/Cd hyperaccumulators, which enhances tolerance to Cd and Zn. We detail a protein encoded by SpH/A within the HMA family that enhances Cd tolerance. Real-time fluorescence quantification (RT-PCR) indicates that SpHMA3 expression in Arabidopsis thaliana and Zea mays KN5585 correlates with high Cd tolerance, linked to Cd accumulation in Zea mays. In addition, homozygous Arabidopsis thaliana AtHMA3 mutants exhibited increased Cd sensitivity compared to the wild type (WT). Notably, plants of Arabidopsis thaliana and maize overexpressing SpHMA3 showed enhanced Cd stress tolerance compared to WT. Enhanced Cd accumulation in tissues was observed when SpHMA3 was overexpressed, as revealed by subcellular distribution analysis. We propose that SpHMA3 augments maize tolerance to Cd and Zn stresses through enhanced cellular uptake and translocation of Cd ions. This investigation clarifies the gene function of SpHMA3 in Cd and Zn stress response, offering insights for enhancing heavy metal absorption traits in maize varieties and phytoremediation methods for soils contaminated with heavy metals.

Fresh purple corn ( Zea mays L.) is rich in anthocyanins, and enhancing its anthocyanin content is crucial for improving its nutritional profile and commercial appeal. Strontium (Sr), an essential human micronutrient involved in physiological processes such as bone formation, exhibits low dietary bioavailability, making the consumption of Sr-enriched agricultural products a critical route for Sr supplementation. Given the biphasic effect of strontium on plant growth, characterized by low-dose stimulation and high-dose inhibition, elucidating its regulatory mechanism in fresh purple corn anthocyanin biosynthesis and breeding cultivars with dual high strontium and anthocyanin traits represents a biofortification strategy with considerable application potential. In this study, a pot experiment was conducted with fresh purple corn, and the anthocyanin and strontium contents in the kernels were quantified. To characterize the dynamic expression profiles of anthocyanin-related genes and metabolite accumulation under strontium treatment, an integrated transcriptomic and metabolomic approach was employed. Key differentially expressed genes were further validated by qRT-PCR. The results demonstrated that strontium treatment significantly increased the anthocyanin content in purple corn kernels relative to the control. Integrated multi-omics analysis revealed that strontium promotes anthocyanin synthesis by activating genes such as Zm00001d003015 , Zm00001d015513 and Zm00001d016471 , enhances the accumulation of pivotal hub metabolites (such as naringin chalcone, 4-coumaric acid), and optimizes the allocation of glycosylation donors by suppressing competing metabolic pathways such as coumarin biosynthesis. Collectively, this study provides the first systematic elucidation of how strontium, as a novel inducer, promotes anthocyanin synthesis in purple corn through a multi-level, temporally regulated network, providing a theoretical foundation and a practical biofortification strategy for developing Sr-enriched, high-anthocyanin maize.