Ming Wu

Leaf angle serves as a crucial determinant of rice plant architecture. The erect leaf phenotype is widely regarded as ideal for achieving high yields. We observed that OsCSN8 overexpression induced leaf erectness at the heading stage, indicating that OsCSN8 regulated leaf angle. This study focused on OsCSN8, a core subunit of COP9 signalosome (CSN), analyzing leaf angle phenotypes in OsCSN8 mutants under varied phytohormone treatments. Integrating Western blot, Bimolecular Fluorescence Complementation, and Yeast Two-Hybrid data elucidated the molecular mechanism: OsCSN8 modulates the second complete leaf angle by interacting with OsBZR1, a central brassinosteroid (BR) signaling transcription factor. Furthermore, at the heading stage, OsCSN8 affected the leaf angle of rice flag leaf by regulating the thickness of adaxial parenchyma and the number of cell layers. These findings reveal the functional role of OsCSN8 in the regulation of rice leaf angle and offer valuable genetic resources for breeding programs focused on agronomic trait improvement.

CSN2, a highly conserved subunit of the COP9 signalosome (CSN), serves as the primary binding site for Cullin in the CSN complex. This interaction, dependent on lysine residues, positions CSN2 as a key player in approximately 20% of CRL-mediated ubiquitination reactions, a critical regulatory pathway for growth, development, and cellular processes in eukaryotes. While the role of CSN2 in human cells has been partially characterized, its function in rice (OsCSN2) remains poorly understood. Building on our previous findings regarding OsCSN2 function under natural light, this study investigates its regulatory mechanisms in rice seedlings under red and far-red light conditions. We demonstrate that under natural light, OsCSN2 mainly affects rice GA homeostasis by regulating the expression of SLR1 and influences rice photomorphogenesis by regulating the expression of the COP1-HY5 complex, thereby controlling rice growth through two pathways. Unlike under natural light, under red light, OsCSN2 promotes the expression of OsGID1, enhances the interaction between OsGID1 and OsSLR1, and promotes GA accumulation and OsPIL14 expression, leading to rice stem growth and inhibition of coleoptile elongation. Under far-red light, OsCSN2 mainly promotes the expression of OsCOP1, increasing the formation of the COP1-HY5 complex, which inhibits photomorphogenesis and coleoptile elongation. Lysine site mutations in OsCSN2 affect the interaction between the OsCSN complex and CRLs, regulating CRL-mediated ubiquitination reactions, promoting the ubiquitin-mediated degradation of OsSLR1 and OsCOP1, and thus promoting rice growth. These findings not only elucidate the functional roles of OsCSN2 in rice growth regulation but also provide valuable genetic resources for breeding rice varieties with enhanced agronomic traits.

Blue light is a significant environmental cue influencing plant photomorphogenesis and regulating plant growth and development. The COP9 signaling complex (CSN), a multi-subunit protein complex, plays a pivotal role in regulating photomorphogenesis, with CSN2 being identified as a key subunit essential for the assembly and function of the CSN. This study investigated the role of OsCSN2 in rice under blue-light conditions. Utilizing OsCSN2 knockout (KO) mutant plants and transgenic overexpression (OE) lines for wild-type (WT) and mutated versions of OsCSN2, we observed significant suppression of the overall seedling phenotype under blue light, indicating that OsCSN2 acts as a negative regulator of blue light-mediated morphogenesis. Further analysis revealed that exogenous application of gibberellin (GA₃) and the GA synthesis inhibitor paclobutrazol (PAC) modulated seedling elongation in response to blue light, particularly affecting plant height, coleoptile, and first incomplete leaf length without altering root growth. This suggests that OsCSN2 mediates the inhibitory effects of blue light on aboveground development through the gibberellin signaling pathway. On day 9, the analyses of endogenous GA₃ levels combined with Western blotting (WB) and quantitative real-time PCR (qRT-PCR) revealed that OsCSN2 senses blue light signals through cryptochrome 2 (CRY2), influences the expression of COP1 and BBX14, and highlights its role in the photoreceptive signaling pathway. This regulation ultimately influences the degradation of SLR1 within the GA signaling pathway, affecting rice seedling growth and development. Our findings also highlight the differential roles of OsCSN1 and OsCSN2 within the CSN in modulating rice seedling photomorphogenesis, thereby providing new insights into the intricate regulatory mechanisms governing plant responses to blue light.

The key flavonoid biosynthesis-related genes and their molecular features in rice have not been comprehensively and systematically characterized. In this study, we investigated the glumes of OsCSN1 mutants and OsCSN2 mutants and found the changes in the total flavonoid contents of the OsCSN2 mutants to be more pronounced than those of the OsCSN1 mutants and the changes in the anthocyanin contents of the OsCSN1 mutants to be more pronounced than those of the OsCSN2 mutants. In addition, key genes related to flavonoid synthesis, OsCHI, showed a more pronounced up-regulation trend, and the OsDFR gene, which encodes a precursor enzyme for anthocyanin synthesis, showed a clear down-regulation trend. And yeast two-hybrid experiments showed that OsCSN1 and OsCSN2 had the ability to interact with OsCUL4. In summary, OsCSN1 and OsCSN2 may regulate the metabolism of flavonoids in rice through CUL4-based E3 ligase, and the two subunits play different roles, laying a foundation for the study of the mechanism of flavonoid metabolism in monocotyledonous plants.

The COP9 signalosome (CSN) is a highly conserved multi-subunit protein complex, with CSN1 being its largest and most conserved subunit. The N-terminal function of CSN1 plays a pivotal and intricate role in plant photomorphogenesis and seedling development. Moreover, CSN is essential for far-red light-mediated photomorphogenesis in seedlings, but the function of OsCSN1 in seedling growth and development under far-red light conditions has not been determined. This study investigates the function of OsCSN1 under far-red light through phenotypic analysis of wild type and OsCSN1 mutant seedlings. Additionally, the effect of the N-terminal region of OsCSN1 on rice seedling growth and development was examined. The addition of exogenous hormone gibberellin (GA3) and gibberellin synthesis inhibitor paclobutrazol (PAC) resulted in notable changes in phenotypes and the expression of key proteins, including CUL4 and SLR1. The findings indicate that OsCSN1 functions as a positive regulator of plant height under far-red light and inhibits root elongation. Under far-red light, OsCSN1 integrates into the COP9 complex and regulates the nuclear localization of COP1. Through its interaction with CUL4 in the CULLIN-RING family, OsCSN1 facilitates the ubiquitin-mediated degradation of SLR1, thereby influencing the growth of rice seedlings. The regulatory function of OsCSN1 in seedling growth and development under far-red light predominantly relies on the 32 amino acids of its N-terminal region. The results of this study can provide new ideas for rice breeding and genetic improvement. Based on the study of key regulatory factors such as OsCSN1, new varieties that can make better use of far-red light signals can be cultivated to enhance crop adaptability and productivity.

The SMALL ACIDIC PROTEIN (SMAP) gene is evolutionarily indispensable for organisms. There are two copies of the SMAP gene in the Arabidopsis thaliana genome, namely, SMAP1 and SMAP2. The function of SMAP2 is similar to that of SMAP1, and both can mediate 2,4-D responses in the root of Arabidopsis. This study cloned the AtSMAP2 genetic promoter sequence. Two promoter fragments of different lengths were designed according to the distribution of their cis-acting elements, and the corresponding β- glucuronidase (GUS) expression vector was constructed. The expression activity of promoters of two lengths, 1993 bp and 997 bp, was studied by the genetic transformation in Arabidopsis. The prediction results of cis-acting elements in the promoter show that there are many hormone response elements in 997 bp, such as three abscisic acid response elements ABRE, gibberellin response elements P-box and GARE-motif and auxin response element AuxRR-core. Through GUS histochemical staining and qRT‒PCR analysis, it was found that the higher promoter activity of P_AtSMAP2-997, compared to P_AtSMAP2-1993, drove the expression of GUS genes at higher levels in Arabidopsis, especially in the root system. The results provide an important basis for subsequent studies on the regulation of AtSMAP2 gene expression and biological functions.

The COP9 signalosome (CSN) is a conserved protein complex, with CSN1 being one of the largest and most important subunits in the COP9 complex. To investigate the N-terminus function of OsCSN1, we edited the N-terminus of OsCSN1 and found that the mutant of OsCSN1 with 102 amino acids missing at the N-terminus showed insensitivity to red light in terms of the embryonic sheath, stem elongation, and main-root elongation. Moreover, the mutant was able to produce, develop, and bear fruit normally. The research results indicate that OsCSN1 is a negative regulator of stem elongation in rice seedlings regulated by red light. Under red-light treatment, OsCSN1 assembles into CSN, which degrades SLR1 through de NEDDylation, affecting PIL11 activity and ultimately inhibiting stem elongation. OsCSN1 also plays an important regulatory role in the inhibition of rice embryonic sheath elongation under red light. By regulating the degradation of SLR1 and PIL14 through the ubiquitin/26S protease pathway, the elongation of the embryonic sheath is ultimately inhibited. OsCSN1 forms a COP9 complex and is modified with RUB/NEDD8 of the E3 ligase of CUL1 to promote the degradation of SLR1 and PIL14, ultimately affecting the elongation of the embryonic sheath. The regulatory domain is located at the N-terminus of CSN1.

The COP9 signalosome (CSN) is a conserved protein complex found in higher eukaryotes, consisting of eight subunits, and it plays a crucial role in regulating various processes of plant growth and development. Among these subunits, CSN2 is one of the most conserved components within the COP9 signalosome complex. Despite its prior identification in other species, its specific function in Oryza sativa L. (Rice) has remained poorly understood. In this study, we investigated the role of CSN2 in rice using gene editing CRISPR/Cas9 technology and overexpression techniques. We created two types of mutants: the oscsn2 mutant and the OsCSN2-OE mutant, both in the background of rice, and also generated point mutants of OsCSN2 (OsCSN2K64E, OsCSN2K67E, OsCSN2K71E and OsCSN2K104E) to further explore the regulatory function of OsCSN2. Phenotypic observation and gene expression analysis were conducted on plants from the generated mutants, tracking their growth from the seedling to the heading stages. The results showed that the loss and modification of OsCSN2 had limited effects on plant growth and development during the early stages of both the wild-type and mutant plants. However, as the plants grew to 60 days, significant differences emerged. The OsCSN2 point mutants exhibited increased tillering compared to the OsCSN2-OE mutant plants, which were already at the tillering stage. On the other hand, the OsCSN2 point mutant had already progressed to the heading and flowering stages, with the shorter plants. These results, along with functional predictions of the OsCSN2 protein, indicated that changes in the 64th, 67th, 71st, and 104th amino acids of OsCSN2 affected its ubiquitination site, influencing the ubiquitination function of CSN and consequently impacting the degradation of the DELLA protein SLR1. Taken together, it can be speculated that OsCSN2 plays a key role in GA and BR pathways by influencing the functional regulation of the transcription factor SLR1 in CSN, thereby affecting the growth and development of rice and the number of tillers.

2,4,6-Trinitrotoluene (TNT) is an aromatic pollutant that is difficult to be degraded in the natural environment. The screening of efficient degrading bacteria for bioremediation of TNT has received much attention from scholars. In this paper, transcriptome analysis of the efficient degrading bacterium Buttiauxella sp. S19-1 revealed that the monooxygenase gene (BuMO) was significantly up-regulated during TNT degradation. S-ΔMO (absence of BuMO gene in S19-1 mutant) degraded TNT 1.66-fold less efficiently than strain S19-1 (from 71.2% to 42.9%), and E-MO mutant (Escherichia coli BuMO-expressing strain) increased the efficiency of TNT degradation 1.33-fold (from 52.1% to 69.5%) for 9 h at 180 rpm at 27 °C in LB medium with 1.4 µg·mL⁻¹ TNT. We predicted the structure of BuMO and purified recombinant BuMO (rBuMO). Its specific activity was 1.81 µmol·min⁻¹·mg⁻¹ protein at pH 7.5 and 35 °C. The results of gas chromatography mass spectrometry (GC–MS) analysis indicated that 4-amino-2,6-dinitrotoluene (ADNT) is a metabolite of TNT biodegradation. We speculate that MO is involved in catalysis in the bacterial degradation pathway of TNT in TNT-polluted environment.

The extensive usage of metal oxide nanoparticles has aided in the spread and accumulation of these nanoparticles in the environment, potentially endangering both human health and the agroecological system. This research describes in detail the hazardous and advantageous impacts of common metal oxide nanomaterials, such as iron oxide, copper oxide, and zinc oxide, on the life cycle of rice. In-depth analyses are conducted on the transport patterns of nanoparticles in rice, the plant’s reaction to stress, the reduction of heavy metal stress, and the improvement of rice quality by metal oxide nanoparticles, all of which are of significant interest in this subject. It is emphasized that from the perspective of advancing the field of nanoagriculture, the next stage of research should focus more on the molecular mechanisms of the effects of metal oxide nanoparticles on rice and the effects of combined use with other biological media. The limitations of the lack of existing studies on the effects of metal oxide nanomaterials on the entire life cycle of rice have been clearly pointed out.