Background/Objectives: Chitinases, enzymes belonging to the glycoside hydrolase family, play a crucial role in plant growth and stress response by hydrolyzing chitin, a natural polymer found in fungal cell walls. This study aimed to identify and analyze the maize chitinase gene family, assessing their response to various biotic and abiotic stresses to understand their potential role in plant defense mechanisms and stress tolerance. Methods: We employed bioinformatics tools to identify 43 chitinase genes in the maize B73_V5 genome. These genes were characterized for their chromosomal positions, gene and protein structures, phylogenetic relationships, functional enrichment, and collinearity. Based on previous RNA-seq data, the analysis assessed the expression patterns of these genes at different developmental stages and under multiple stress conditions. Results: The identified chitinase genes were unevenly distributed across maize chromosomes with a history of tandem duplications contributing to their divergence. The ZmChi protein family was predominantly hydrophilic and localized mainly in chloroplasts. Expression analysis revealed that certain chitinase genes were highly expressed at specific developmental stages and in response to various stresses, with ZmChi31 showing significant responsiveness to 11 different abiotic and biotic stresses. Conclusions: This study provides new insights into the role of chitinase genes in maize stress response, establishing a theoretical framework for exploring the molecular basis of maize stress tolerance. The identification of stress-responsive chitinase genes, particularly ZmChi31, offers potential candidates for further study in enhancing maize resistance to environmental challenges.

Laccase (LAC) is a diverse group of genes found throughout the plant genome essential for plant growth and the response to stress by converting monolignin into intricate lignin formations. However, a comprehensive investigation of maize laccase has not yet been documented. A bioinformatics approach was utilized in this research to conduct a thorough examination of maize (Zea mays L.), resulting in the identification and categorization of 22 laccase genes (ZmLAC) into six subfamilies. The gene structure and motifs of each subgroup were largely consistent. The distribution of the 22 LAC genes was uneven among the maize chromosomes, with the exception of chromosome 9. The differentiation of the genes was based on fragment replication, and the differentiation time was about 33.37 million years ago. ZmLAC proteins are primarily acidic proteins. There are 18 cis-acting elements in the promoter sequences of the maize LAC gene family associated with growth and development, stress, hormones, light response, and stress response. The analysis of tissue-specific expression revealed a high expression of the maize LAC gene family prior to the V9 stage, with minimal expression at post-V9. Upon reviewing the RNA-seq information from the publicly available transcriptome, it was discovered that ZmLAC5, ZmLAC10, and ZmLAC17 exhibited significant expression levels when exposed to various biotic and abiotic stress factors, suggesting their crucial involvement in stress responses and potential value for further research. This study offers an understanding of the functions of the LAC genes in maize’s response to biotic and abiotic stress, along with a theoretical basis for comprehending the molecular processes at play.

Appropriate reference genes must be selected for accurate qRT-PCR data to conduct a thorough gene expression analysis in the sorghum aphid (Melanaphis sacchari, Hemiptera, Aphididae). This approach will establish a foundation for gene expression analysis and determines the efficacy of RNA interference in the sorghum aphid. Nine potential reference genes, including Actin, 18S, GAPDH, RPL7, EF-1α, EF-1β, 28S, HSP70, and TATA, were assessed under various experimental conditions to gauge their suitability based on qRT-PCR Ct values. The stability of these candidate reference genes in diverse experimental setups was analyzed employing several techniques, including the ΔCt comparative method, geNorm, Normfinder, BestKeeper, and RefFinder. The findings revealed that the quantity of ideal reference genes ascertained by the geNorm method for diverse experimental conditions remained consistent. For the developmental stages of the sorghum aphid, RPL7 and 18S proved to be the most dependable reference genes, whereas GAPDH and EF-1β were recommended as the most stable reference genes for different tissues. In experiments involving wing dimorphism, EF-1α and GAPDH were identified as the optimal reference gene pair. Under varying temperatures, EF-1α and EF-1β were found to be the most dependable gene pair. For studies focusing on insecticide susceptibility, 18S and TATA emerged as the most stable candidate reference genes. Across all experimental conditions, EF-1α and EF-1β was the optimal combination of reference genes in the sorghum aphid. This research has pinpointed stable reference genes that can be utilized across various treatments, thereby enhancing gene expression studies and functional genomics research on the sorghum aphid.

Introduction: Phenylalanine ammonia-lyase (PAL), as the rate-limiting enzyme in plant phenylpropanoid metabolism, catalyzes the conversion of L-phenylalanine to trans-cinnamic acid and plays a pivotal role in plant-insect resistance mechanisms.Methods: Utilizing a maize pangenome constructed from 26 high-quality genomes, we systematically identified the ZmPAL gene family members. Evolutionary pressure and structural variation (SV) analyses were conducted, alongside reanalysis of publicly available RNA-seq datasets under lepidopteran stress conditions. Temporal expression patterns were further validated via qRT-PCR.Results: This investigation identified 29 ZmPAL genes, comprising 7 core, 2 near-core, 12 dispensable, and 8 private genes, revealing substantial limitations of single-reference genome-based studies. Evolutionary analysis indicated positive selection of ZmPAL8 in specific germplasms, while SV-affected ZmPAL5 exhibited significantly divergent expression patterns. Conserved expression profiles were observed among ZmPAL members under diverse lepidopteran stresses. Temporal-specific regulation was established: ZmPAL7, ZmPAL10, and ZmPAL23 dominated early defense responses, whereas ZmPAL10 and ZmPAL23 maintained predominance during mid-late phases.Discussion: This pangenome-based study provides novel insights into PAL-mediated phytoprotective mechanisms against lepidopteran pests and establishes a theoretical framework for understanding maize's molecular adaptation to biotic stressors.

Callose is widely present in higher plants and plays a significant role in plant growth, development, and response to various stresses. Although numerous studies have highlighted the importance of the callose synthase (CalS) genes, their role in the resistance of sorghum (Sorghum bicolor) to aphids (Melanaphis sacchari) remains limitedly understood. This study identified 11 sorghum callose synthase genes (SbCalS), unevenly distributed across four chromosomes of sorghum. All SbCalS proteins contain glucan synthase and Fks1 domains, with segmental duplication playing a major role in gene diversification. Cis-element prediction revealed the presence of numerous stress-responsive elements, indicating that this gene family is primarily involved in stress resistance. Using published RNA-seq data, we discovered the differential expression of the SbCalS5 gene between resistant and susceptible sorghum varieties. Real-time quantitative PCR (qPCR) analysis confirmed the relative expression levels of all SbCalS members under aphid stress. To further verify the role of callose in sorghum, we measured the callose content in both resistant and susceptible sorghum varieties. The results indicated that callose plays a critical role in aphid resistance in sorghum, particularly the SbCalS5 gene. This study provides a reference for further investigation into the role of callose synthase genes in sorghum aphid resistance.

Juvenile hormone binding proteins (JHBPs) are carrier proteins that bind to juvenile hormone (JH) to form a complex, which then transports the JH to target organs to regulate insect growth and development. Through bioinformatics analysis, 76 genes encoding JHBP in S. frugiperda were identified from whole genome data (SfJHBP1-SfJHBP76). These genes are unevenly distributed across 8 chromosomes, with gene differentiation primarily driven by tandem duplication. Most SfJHBP proteins are acidic, and their secondary structures are mainly composed of α-helices and random coils. Gene structure and conserved motif analyses reveal significant variations in the number of coding sequences (CDS) and a high diversity in amino acid sequences. Phylogenetic analysis classified the genes into four subfamilies, with a notable presence of directly homologous genes between S. frugiperda and S. litura, suggesting a close relationship between the two species. RNA-seq data from public databases and qPCR of selected SfJHBP genes show that SfJHBP20, SfJHBP50, and SfJHBP69 are highly expressed at most developmental stages, while SfJHBP8 and SfJHBP14 exhibit specific expression during the pupal stage and in the midgut. These findings provide a theoretical basis for future studies on the biological functions of this gene family.