Speed breeding represents a pivotal technology for enhancing crop breeding efficiency. This study systematically examined the regulation of LED light environments, planting density, and gibberellic acid (GA₃) on rice growth cycle progression in plant factories, establishing an integrated speed breeding protocol. The experimental design comprised three components: (1) coupling seedling age (9–25 days, variety-dependent) with LED environments and planting densities (25–100 plants/tray); (2) combining light intensity gradients (450 and 900 μmol·m⁻²·s⁻¹) with photoperiod control; (3) applying GA₃ gradients (0–120 ppm) to enhance immature seed germination. Results indicated that high planting densities (>50 plants/tray) prolonged the growth cycle and decreased yield, whereas 25 plants/tray optimally balanced growth cycle shortening and yield maximization. Under short-day induction, Nipponbare (Nip) and Wufeng B (WFB) reached heading at 39 and 58 days after sowing (DAS), respectively. Stage-specific light responses were observed: 450 μmol·m⁻²·s⁻¹ during the basic vegetative phase (BVP) promoted morphological development, whereas 900 μmol·m⁻²·s⁻¹ during the photoperiod-sensitive phase (PSP) accelerated tillering and panicle differentiation. GA₃ treatment (60 ppm) enhanced the germination rate of immature seeds by 31%. The optimized lightregimes comprised natural light + 900 μmol·m⁻²·s⁻¹ (NL–900) and 450 μmol·m⁻²·s⁻¹ + 900 μmol·m⁻²·s⁻¹ (450–900), combined with density control (25 plants/tray) and GA₃-mediated immature seed utilization, shortened the generation time to 54 days and 70 days for Nip and WFB, respectively. This integrated protocol establishes an efficient strategy for rice speed breeding in plant factories.

Arylsulfatases exhibit great potential in industry for desulfation applications, but less is known about the metallo-β-lactamase (MBL) fold arylsulfatases. To learn more about them, an MBL fold arylsulfatase from Pseudoalteromonas atlantica T6c (PaAst) was identified and characterized, and its structure was elaborated in this study. PaAst was sequence analyzed, heterologously expressed in E. coli, purified by Ni²⁺-NTA resin affinity chromatography and size-exclusion chromatography, functionally studied by p-nitrophenyl sulfate (pNPS), and crystallized for structure determination. The MBL fold arylsulfatase was identified by sequence analysis and confirmed by enzymatic assay on pNPS with K_m 1.00 mM and V_max 60.80 U/mg at 50 °C and pH 7.5. Furthermore, its crystals were obtained in 0.2 M sodium thiocyamate, 20% PEG3350, and its structure was determined at 2.0 Å that formed a dimer with MBL fold. Our work highlighted the MBL fold arylsulfatases from structural insights and could be the theoretical foundation for investigations into their catalytic mechanism.

Rice is a short-day thermophilic crop that originated from the low latitudes of the tropics and subtropics; it requires high temperatures for growth but is sensitive to low temperatures. Therefore, it is highly important to explore and analyze the molecular mechanism of cold tolerance in rice to expand rice planting areas. Here, we report a phenotypic evaluation based on low-temperature stress in indica rice (R998) and wild rice (GZW) and a comparative transcriptomic study conducted at six time points. After 7 days of low-temperature treatment at 10 °C, R998 exhibited obvious yellowing and greening of the leaves, while GZW exhibited high low-temperature resistance, and the leaves maintained their normal morphology and exhibited no yellowing; GZW has a higher survival rate. Principal component analysis (PCA) and cluster analysis of the RNA-seq data revealed that the difference in low-temperature resistance between the two cultivars was caused mainly by the difference in low-temperature treatment after 6 h. Differential expression analysis revealed 2615 unique differentially expressed genes (DEGs) in the R998 material, 1578 unique DEGs in the GZW material, 1874 unique DEGs between R998 and GZW, and 2699 DEGs that were differentially expressed not only between cultivars but also at different time points in the same material under low-temperature treatment. A total of 15,712 DEGs were detected and were significantly enriched in the phenylalanine metabolism, photosynthesis, plant hormone signal transduction, and starch and sucrose metabolism pathways. These 15,712 DEGs included 1937 genes encoding transcription factors (TFs), of which 10 have been identified with functional validation in previous studies. In addition, a gene regulatory network was constructed via weighted gene correlation network analysis (WGCNA), and 12 key genes related to low-temperature tolerance in rice were identified, including five genes encoding TFs, one of which was identified and verified in previous studies. These results provide a theoretical basis for an in-depth understanding of the molecular mechanism of low-temperature tolerance in rice and provide new genetic resources for the study of low-temperature tolerance in rice.

Salt stress is an injurious concern of global climate change that negatively impacts the growth and yield of rice plants. Identifying salt tolerance genes is essential to understanding the molecular mechanism regulating salt tolerance in rice. In this study, we treated two rice varieties, Xiangxiuzhan (XXZ) and Changxiang (CXG), with 100 mM NaCl to examine the effect on the germination and growth stages. Transcriptome analysis was investigated for changes in gene expression between the two varieties. During the germination stage, the CXG variety had higher germination potential than the XXZ variety, whereas in the growth stage, the XXZ variety showed higher survival efficiency than the CXG variety. Transcriptome analysis showed that the XXZ variety had more DEGs in grains, while CXG displayed greater DEGs in leaves and roots. Gene Ontology (GO) and KEGG pathway showed that beta-alanine metabolism, cutin biosynthesis, and plant hormone signal transduction were over-represented, whereas heatmap analysis showed cellular and environmental signal transduction. This study focuses on the molecular pathways of the salt stress tolerance mechanism of Xiangxiuzhan and Changxiang varieties.