Like other important cereal crop in modern agricultural production, maize is also threatened by drought. And the drought stress during maize filling stage will directly affect the quality (protein or oil concentration) and also the weight of grain. Therefore, different from previous studies focusing on inbred lines and pot experiment at seedling stage, current study selected filling stage of the adult plant and planting maize in the experimental field. Two hybrids cultivars with different drought tolerant were used for drought and water treatment respectively. We performed transcriptome sequencing analysis of 4 groups, 12 samples, and obtained 651.08 million raw reads. Then the data were further processed by mapping to a reference genome, GO annotation, enrichment analysis and so on. Among them we focus on the different change trends of water treatment and drought treatment, and the different responses of two drought-tolerant cultivars to drought treatment. Through the analysis, several transcripts which encode nitrogen metabolic, protein phosphorylation, MYB,AP2/ERF, HB transcriptional factor, O-glycosyl hydrolases and organic acid metabolic process were implicated with maize drought stress. Our data will offer insights of the identification of genes involved in maize drought stress tolerance, which provides a theoretical basis for maize drought resistance breeding.

Cellulose is the world’s most abundant renewable energy resource, and a variety of cellulose synthase genes are involved in the biosynthesis of cellulose. In the process of cellulose synthesis, all cellulose synthases are interrelated and act synergistically. In this study, we analyzed the contents of cellulose, hemicellulose, and lignin in the different parts and tissues of E. grandis. The results showed that the cellulose content had greater differences among three different heights. On this basis, we carried out the transcriptome-wide profiling of gene expression patterns using RNA sequencing. A total of 2066 differentially expressed genes were identified for three pairwise comparisons between three different heights, most of which were related to the programmed photosynthetic membrane and photosystem. A total of 100 transcripts of CSs (58 CesA and 42 Csl) were obtained from transcriptome libraries. The expression pattern of these genes indicated that different CS genes had a wide range of expression profiles. A phylogenetic analysis of 135 reference CS genes showed that the CSs of E. grandis were clustered into six major groups (CesA1-9, CslA, CslB/H, CslD, CslE, and CslG). Based on the weighted gene co-expression network analysis, a dual-directional regulation mechanism between Csl and CesA proteins in the cellulose biosynthesis was identified. The gene expression profile analysis, using qRT-PCR in different tissues of E. grandis, demonstrated that the CSs were highly expressed in xylem, and CesAs had a higher relative expression than Csls. The analysis of sequence similarity combined with the expression pattern indicated that the CesA1, 3, and 6 transcripts were associated with the biosynthesis of the secondary cell wall, and CesA4, 5, and 7 transcripts were more likely to associate with the biosynthesis of the primary cell wall. Finally, the qRT-PCR analysis confirmed the expression of 11 selected CSs in three different parts of E. grandis.

Acanthus ilicifolius is an important medicinal plant in mangrove forests, which is rich in secondary metabolites with various biological activities. In this study, we used transcriptomic analysis to obtain differentially expressed genes in the flavonoid metabolic pathway and metabolomic methods to detect changes in the types and content in the flavonoid metabolic synthesis pathway. The results showed that DEGs were identified in the mature roots vs. leaves comparison (9001 up-regulated and 8910 down-regulated), mature roots vs. stems comparison (5861 up-regulated and 7374 down-regulated), and mature stems vs. leaves comparison (10,837 up-regulated and 11,903 down-regulated). Furthermore, two AiCHS genes and four AiCHI genes were up-regulated in the mature roots vs. stems of mature A. ilicifolius, and were down-regulated in mature stems vs. leaves, which were highly expressed in the A. ilicifolius stems. A total of 215 differential metabolites were found in the roots vs. leaves of mature A. ilicifolius, 173 differential metabolites in the roots vs. stems, and 228 differential metabolites in the stems vs. leaves. The metabolomic results showed that some flavonoids in A. ilicifolius stems were higher than in the roots. A total of 18 flavonoid differential metabolites were detected in the roots, stems, and leaves of mature A. ilicifolius. In mature leaves, quercetin-3-O-glucoside-7-O-rhamnoside, gossypitrin, isoquercitrin, quercetin 3,7-bis-O-β-D-glucoside, and isorhamnetin 3-O-β-(2″-O-acetyl-β-D-glucuronide) were found in a high content, while in mature roots, di-O-methylquercetin and isorhamnetin were the major compounds. The combined analysis of the metabolome and transcriptome revealed that DEGs and differential metabolites were related to flavonoid biosynthesis. This study provides a theoretical basis for analyzing the molecular mechanism of flavonoid synthesis in A. ilicifolius and provides a reference for further research and exploitation of its medicinal value.

Handroanthus and Tabebuia are known for their ornamental and medicinal value, which are attributed to metabolites. However, the mechanisms underlying the synthesis of these metabolites are poorly understood. In this study, the expression levels of secondary metabolites and the mechanism of flavonoid biosynthesis in the bark and leaves of Handroanthus chrysantha (Jaq.) were examined using transcriptomic and metabolomic techniques. Metabolic analysis identified several differentially accumulated metabolites (DAMs), most of which were flavonoids, isoprenoids, and sterols. Additionally, 30 flavonoids were identified in the bark and leaves of H. chrysantha. Transcriptomic analysis identified 69 genes involved in flavonoid biosynthesis, among which 49 were significantly different between the bark and leaves. qRT-PCR analysis of eight genes involved in flavonoid biosynthesis showed that the expression patterns of the genes were consistent with the transcriptome sequencing data. Integrative transcriptomic and metabolomic analysis showed that 20 differentially expressed genes (DEGs) associated with flavonoid biosynthesis were strongly correlated with seven DAMs, confirming the involvement of the DEGs in flavonoid biosynthesis. These findings considerably contribute to the understanding of the biosynthesis of secondary metabolites in H. chrysantha and serve as a reference for further pharmacological studies.