Characterization, Expression Profiling, and Biochemical Analyses of the Cinnamoyl-CoA Reductase Gene Family for Lignin Synthesis in Alfalfa Plants

Genome-wide identification and expression pattern analysis of the cinnamoyl-CoA reductase gene family in flax (Linum usitatissimum L.)

BACKGROUND

Cinnamoyl-CoA reductase (CCR) is the first important and committed enzyme in the monolignol synthesis branch of the lignin biosynthesis (LB) pathway, catalyzing the conversion of cinnamoyl-CoAs to cinnamaldehydes and is crucial for the growth of Linum usitatissimum (flax), an important fiber crop. However, little information is available about CCR in flax (Linum usitatissimum L.).

RESULTS

In this study, we conducted a genome-wide analysis of the CCR gene family and identified a total of 22 CCR genes. The 22 CCR genes were distributed across 9 chromosomes, designated LuCCR1-LuCCR22. Multiple sequence alignment and conserved motif analyses revealed that LuCCR7/13/15/20 harbor completely conserved NADP-specific, NAD(P)-binding, and CCR signature motifs. Furthermore, each of these LuCCRs is encoded by 5 exons separated by 4 introns, a characteristic feature of functional CCRs. Phylogenetic analysis grouped LuCCRs into two clades, with LuCCR7/13/15/20 clustering with functional CCRs involved in LB in dicotyledonous plants. RNA-seq analysis indicated that LuCCR13/20 genes are highly expressed throughout all flax developmental stages, particularly in lignified tissues such as roots and stems, with increased expression during stem maturation. These findings suggest that LuCCR13/20 play crucial roles in the biosynthesis process of flax lignin. Additionally, LuCCR2/5/10/18 were upregulated under various types of abiotic stress, highlighting their potential roles in flax defense-related processes.

CONCLUSIONS

This study systematically analyzes the CCR gene family (CCRGF) of flax (Linum usitatissimum L.) at the genomic level for the first time, so as to select the whole members of the CCRGF of flax and to ascertain their potential roles in lignin synthesis. Therefore, in future work, we can target genetic modification of LuCCR13/20 to optimize the content of flax lignin. As such, this research establishes a theoretical foundation for studying LuCCR gene functions and offers a new perspective for cultivating low-lignin flax varieties.

Systematic characterization of cinnamyl alcohol dehydrogenase members revealed classification and function divergence in Haplomitrium mnioides

Cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) is considered to be a key enzyme in lignin biosynthesis, which can catalyze cinnamyl aldehyde to produce cinnamyl alcohol. In this study, three putative CADs were characterized from the liverwort Haplomitrium mnioides. The sequence alignment and phylogenetic analysis revealed that HmCADs belonged to a multigene family, with three HmCADs belonging to class II, class III, and class IV, respectively. In vitro enzymatic studies demonstrated that HmCAD2 exhibited high affinity and catalytic activity towards five cinnamyl aldehydes, followed by HmCAD3 with poor catalytic activity, and HmCAD1 catalyzed only the reaction of p-coumaryl aldehyde and coniferyl aldehyde with extremely low catalytic capacity. Protein-substrate binding simulations were performed to investigate the differences in catalytic activity exhibited when proteins catalyzed different substrates. Furthermore, distinct expression patterns of three HmCADs were identified in different plant tissues. Subcellular localization tests confirmed that HmCAD1/2/3 was located in the cytoplasm. The simulated responses of HmCADs to different stresses showed that HmCAD1 played a positive role in coping with each stress, while HmCAD2/3 was weak. These findings demonstrate the diversity of CADs in liverwort, highlight the divergent role of HmCAD1/2/3 in substrate catalysis, and also suggest their possible involvement in stress response, thereby providing new insights into CAD evolution while emphasizing their potential distinctive and collaborative contributions to the normal growth of primitive liverworts.

Metabolite differences and molecular mechanism between dehiscent and indehiscent capsule of mature sesame

The loss of sesame capsule seed prior to harvest poses a significant economical challenge in mechanized production. The metabolites involved in capsule closure are still unclear. Using comparative metabolome and transcriptome analysis, this work investigated the molecular regulation and enrichment pathways in two sesame types of indehiscent capsule WanZhi28 (ND) and dehiscent capsule WanZhi2 (WZ2). The findings demonstrated that genes and metabolites were significantly enriched in lignin synthesis-related pathways. Furthermore, data suggests that lipid and sugar metabolism may have an impact on capsule closure. Apart from its function in cell signaling, the latter may contribute to the glycosylation of lignin monomers, while the former may provide ATP for cellular microtubule movement. This work concurrently focused on a large number of differentially expressed transcription factors linked to the sesame capsule's anti-cleft mechanism, providing new evidence for the discovery and use of functional markers and genes for capsule dehiscence. The identification of key pathways and regulatory mechanisms offers valuable information for developing strategies to mitigate seed loss during harvest, ultimately contributing to more efficient and profitable sesame production.

Bacillus australimaris protect Gloriosa superba L. against Alternaria alternata infestation

Gloriosa superba L., a medicinally important plant, is often affected by leaf blight disease caused by Alternaria alternata, which compromises its productivity. This study explores the protective effects of Bacillus australimaris endophyte (NBRI GS34), demonstrating that its inoculation not only inhibits the disease but also promotes plant growth and increases the concentrations of bioactive metabolites. Co-culturing NBRI GS34 with A. alternata significantly boosts protease (30-50%) and chitinase (6-28%) activities, evidencing a synergistic interaction. Scanning electron microscopy and GC-MS analysis confirm NBRI GS34's antagonistic action and reveal antifungal compounds like undecanoic acid and benzene carboxylic acid in treatments. Greenhouse experiments show a 78% reduction in disease incidence with NBRI GS34 treatment, enhancing vegetative growth and upregulating defense-related genes. Additionally, HPLC analysis reveals increased gloriosine and colchicine concentrations by 52% and 33%, respectively. These findings suggest NBRI GS34 could serve as a sustainable fungicide alternative, enhancing the production of medically valuable compounds and highlighting its potential pharmaceutical applications.

Modifying lignin: A promising strategy for plant disease control

Lignin is a complex polymer found in the cell walls of plants, providing structural support and protection against pathogens. By modifying lignin composition and structure, scientists aim to optimize plant defense responses and increase resistance to pathogens. This can be achieved through various genetic engineering techniques which involve manipulating the genes responsible for lignin synthesis. By either up regulating or down regulating specific genes, researchers can alter the lignin content, composition, or distribution in plant tissues. Reducing lignin content in specific tissues like leaves can improve the effectiveness of defense mechanisms by allowing for better penetration of antimicrobial compounds. Overall, Lignin modification through techniques has shown promising results in enhancing various plants resistance against pathogens. Furthermore, lignin modification can have additional benefits beyond pathogen resistance. It can improve biomass processing for biofuel production by reducing lignin recalcitrance, making the extraction of sugars from cellulose more efficient. The complexity of lignin biosynthesis and its interactions with other plant components make it a challenging target for modification. Additionally, the potential environmental impact and regulatory considerations associated with genetically modified organisms (GMOs) require careful evaluation. Ongoing research aims to further optimize this approach and develop sustainable solutions for crop protection.

Response characterization and target site mechanism study in glyphosate-resistant populations of Lolium multiflorum L. from Brazil

Italian ryegrass (Lolium multiflorum L.) is an invasive species widely spread in croplands worldwide. The intensive use of glyphosate has resulted in the selection of resistance to this herbicide in Italian ryegrass. This work characterized the response to glyphosate of Italian ryegrass populations from the South and Southwest regions of Paraná, Brazil. A total of 44 Italian ryegrass populations were collected in farming areas, and were classified for glyphosate resistance with 75% of populations resistant to gloyphosate. Of these, 3 resistant (VT05AR, MR20AR and RN01AR) and three susceptible (VT07AS, MR05AS and RN01AS) of these populations were selected to determine the resistance level and the involvement of the target site mechanisms for glyphosate resistance. Susceptible populations GR50 ranged from 165.66 to 218.17 g.e.a. ha-1 and resistant populations from 569.37 to 925.94, providing RI ranging from 2.88 and 4.70. No mutation in EPSPS was observed in the populations, however, in two (MR20AR and RN02AR) of the three resistant populations, an increase in the number of copies of the EPSPs gene (11 to 57×) was detected. The number of copies showed a positive correlation with the gene expression (R2 = 0.86) and with the GR50 of the populations (R2 = 0.81). The increase in EPSPS gene copies contributes to glyphosate resistance in Italian ryegrass populations from Brazil.

Gibberellic acid sensitive dwarf encodes an ARPC2 subunit that mediates gibberellic acid biosynthesis, effects to grain yield in rice

The plant hormone gibberellic acid (GA) is important for plant growth and productivity. Actin-related proteins (ARPs) also play central roles in plant growth, including cell elongation and development. However, the relationships between ARPs and GA signaling and biosynthesis are not fully understood. Here, we isolated OsGASD, encoding an ARP subunit from rice (Oryza sativa), using the Ac/Ds knockout system. The osgasd knockout (Ko) mutation reduced GA3 content in shoots as well as plant growth and height. However, GA application restored the plant height of the osgasd Ko mutant to a height similar to that of the wild type (WT). Rice plants overexpressing OsGASD (Ox) showed increased plant height and grain yield compared to the WT. Transcriptome analysis of flag leaves of OsGASD Ox and osgasd Ko plants revealed that OsGASD regulates cell development and the expression of elongation-related genes. These observations suggest that OsGASD is involved in maintaining GA homeostasis to regulate plant development, thereby affecting rice growth and productivity.