UPLC-MS/MS Profile Combined With RNA-Seq Reveals the Amino Acid Metabolism in Zanthoxylum bungeanum Leaves Under Drought Stress

An Evaluation of the Effects of Pepper (Zanthoxylum bungeanum Maxim.) Leaf Extract on the Physiochemical Properties and Water Distribution of Chinese Cured Meat (Larou) During Storage

In this study, pepper (Zanthoxylum bungeanum Maxim.) leaf (ZL) extract was added to larou to investigate the improvement in the quality of physicochemical properties, texture, water distribution, and microorganism growth during storage for 20 days. Based on the results, the addition of ZL extract significantly retarded the increase in cooking loss, TBARS value, hardness, and microorganism growth. Moreover, the addition of ZL extract decreased the pH value, lightness, and microorganism counts, and increased the moisture content, total soluble protein content, a* value, b* value, and chewiness. The LF-NMR results showed that the addition of ZL extract shortened the T2 relaxation time and boosted the proportion of immobilized water, facilitating the validation of the improvement in water retention of larou during storage. The FT-IR results indicated that the addition of ZL extract influenced the protein secondary structure by inducing the conversion of α-helices to β-sheet structures. Accordingly, ZL extract has the potential to serve as a natural antioxidant, effectively helping to ameliorate the quality properties of cured meat products during storage.

Multi-omics integration analysis reveals the molecular mechanisms of drought adaptation in homologous tetraploid alfalfa(Medicago sativa 'Xinjiang-Daye')

Drought stress is a predominant abiotic factor leading to decreased alfalfa yield. Genomic ploidy differences contribute to varying adaptation mechanisms of different alfalfa cultivars to drought conditions. This study employed a multi-omics approach to characterize the molecular basis of drought tolerance in a tetraploid variant of alfalfa (Medicago sativa, Xinjiang-Daye). Under drought treatment, a total of 4446 genes, 859 proteins, and 524 metabolites showed significant differences in abundance. Integrative analysis of the multi-omics data revealed that regulatory modules involved in flavonoid biosynthesis, plant hormone signalling transduction, linoleic acid metabolism, and amino acid biosynthesis play crucial roles in alfalfa adaptation to drought stress. The severity of drought led to the substantial accumulation of flavonoids, plant hormones, free fatty acids, amino acids, and their derivatives in the leaves. Genes such as PAL, 4CL, CHI, CHS, PP2C, ARF_3, and AHP_4 play pivotal regulatory roles in flavonoid biosynthesis and hormone signalling pathways. Differential expression of the LOX gene emerged as a key factor in the elevated levels of free fatty acids. Upregulation of P5CS_1 and GOT1/2 contributed significantly to the accumulation of Pro and Phe contents. ERF19 emerged as a principal positive regulator governing the synthesis of the aforementioned compounds. Furthermore, observations suggest that Xinjiang-Daye alfalfa may exhibit widespread post-transcriptional regulatory mechanisms in adapting to drought stress. The study findings unveil the critical mechanisms by which Xinjiang-Daye alfalfa adapts to drought stress, offering novel insights for the improvement of alfalfa germplasm resources.

Integrative physiological, metabolomic, and transcriptomic analysis reveals the drought responses of two apple rootstock cultivars

BACKGROUND

Drought is considered the main environmental factor restricting apple production and thus the development of the apple industry. Rootstocks play an important role in enhancing the drought tolerance of apple plants. Studies of the physiology have demonstrated that 'ZC9-3' is a strong drought-resistant rootstock, whereas 'Jizhen-2' is a weak drought-resistant rootstock. However, the metabolites in these two apple rootstock varieties that respond to drought stress have not yet been characterized, and the molecular mechanisms underlying their responses to drought stress remain unclear.

RESULTS

In this study, the physiological and molecular mechanisms underlying differences in the drought resistance of 'Jizhen-2' (drought-sensitive) and 'ZC9-3' (drought-resistant) apple rootstocks were explored. Under drought stress, the relative water content of the leaves was maintained at higher levels in 'ZC9-3' than in 'Jizhen-2', and the photosynthetic, antioxidant, and osmoregulatory capacities of 'ZC9-3' were stronger than those of 'Jizhen-2'. Metabolome analysis revealed a total of 95 and 156 differentially accumulated metabolites in 'Jizhen-2' and 'ZC9-3' under drought stress, respectively. The up-regulated metabolites in the two cultivars were mainly amino acids and derivatives. Transcriptome analysis revealed that there were more differentially expressed genes and transcription factors in 'ZC9-3' than in 'Jizhen-2' throughout the drought treatment. Metabolomic and transcriptomic analysis revealed that amino acid biosynthesis pathways play key roles in mediating drought resistance in apple rootstocks. A total of 13 metabolites, including L-α-aminoadipate, L-homoserine, L-threonine, L-isoleucine, L-valine, L-leucine, (2S)-2-isopropylmalate, anthranilate, L-tryptophan, L-phenylalanine, L-tyrosine, L-glutamate, and L-proline, play an important role in the difference in drought resistance between 'ZC9-3' and 'Jizhen-2'. In addition, 13 genes encoding O-acetylserine-(thiol)-lyase, S-adenosylmethionine synthetase, ketol-acid isomeroreductase, dihydroxyacid dehydratase, isopropylmalate isomerase, branched-chain aminotransferase, pyruvate kinase, 3-dehydroquinate dehydratase/shikimate 5-dehydrogenase, N-acetylglutamate-5-P-reductase, and pyrroline-5-carboxylate synthetase positively regulate the response of 'ZC9-3' to drought stress.

CONCLUSIONS

This study enhances our understanding of the response of apple rootstocks to drought stress at the physiological, metabolic, and transcriptional levels and provides key insights that will aid the cultivation of drought-resistant apple rootstock cultivars. Especially, it identifies key metabolites and genes underlying the drought resistance of apple rootstocks.

Integrated physiological, transcriptomic, and metabolomic analyses of drought stress alleviation in Ehretia macrophylla Wall. seedlings by SiO2 NPs (silica nanoparticles)

With environmental problems such as climate global warming, drought has become one of the major stress factors, because it severely affects the plant growth and development. Silicon dioxide nanoparticles (SiO2 NPs) are crucial for mitigating abiotic stresses suffered by plants in unfavorable environmental conditions and further promoting plant growth, such as drought. This study aimed to investigate the effect of different concentrations of SiO2 NPs on the growth of the Ehretia macrophylla Wall. seedlings under severe drought stress (water content in soil, 30-35%). The treatment was started by starting spraying different concentrations of SiO2 NPs on seedlings of Ehretia macrophyla, which were consistently under normal and severe drought conditions (soil moisture content 30-35%), respectively, at the seedling stage, followed by physiological and biochemical measurements, transcriptomics and metabolomics analyses. SiO2 NPs (100 mg·L-1) treatment reduced malondialdehyde and hydrogen peroxide content and enhanced the activity of antioxidant enzymes under drought stress. Transcriptomic analysis showed that 1451 differentially expressed genes (DEGs) in the leaves of E. macrophylla seedlings were regulated by SiO2 NPs under drought stress, and these genes mainly participate in auxin signal transduction and mitogen-activated protein kinase signaling pathways. This study also found that the metabolism of fatty acids and α-linolenic acids may play a key role in the enhancement of drought tolerance in SiO2 NP-treated E. macrophylla seedlings. Metabolomics studies indicated that the accumulation level of secondary metabolites related to drought tolerance was higher after SiO2 NPs treatment. This study revealed insights into the physiological mechanisms induced by SiO2 NPs for enhancing the drought tolerance of plants.

Integrated Metabolome and Transcriptome Analyses Reveal Amino Acid Biosynthesis Mechanisms during the Physiological Maturity of Grains in Yunnan Hulled Wheat (Triticum aestivum ssp. yunnanense King)

Yunnan hulled wheat (YHW) possesses excellent nutritional characteristics; however, the precise amino acid (AA) composition, contents, and molecular mechanisms underlying AA biosynthesis in YHW grains remain unclear. In this study, we aimed to perform metabolomic and transcriptomic profiling to identify the composition and genetic factors regulating AA biosynthesis during the physiological maturation of grains of two YHW genotypes, Yunmai and Dikemail, with high and low grain protein contents, respectively. A total of 40 and 14 differentially accumulated amino acids (AAs) or AA derivatives were identified between the waxy grain (WG) and mature grain (MG) phenological stages of Yunmai and Dikemail, respectively. The AA composition differed between WG and MG, and the abundance of AAs-especially that of essential AAs-was significantly higher in WG than in MG (only 38.74-58.26% of WG). Transcriptome analysis revealed differential regulation of structural genes associated with the relatively higher accumulation of AAs in WG. Weighted gene co-expression network analysis and correlation analyses of WG and MG indicated differences in the expression of clusters of genes encoding both upstream elements of AA biosynthesis and enzymes that are directly involved in AA synthesis. The expression of these genes directly impacted the synthesis of various AAs. Together, these results contribute to our understanding of the mechanism of AA biosynthesis during the different developmental stages of grains and provide a foundation for further research to improve the nutritional value of wheat products.

Transcriptome and UPLC-MS/MS reveal mechanisms of amino acid biosynthesis in sweet orange 'Newhall' after different rootstocks grafting

Sweet orange 'Newhall' (C. sinensis) is a popular fruit in high demand all over the world. Its peel and pulp are rich in a variety of nutrients and are widely used in catering, medicine, food and other industries. Grafting is commonly practiced in citrus production. Different rootstock types directly affect the fruit quality and nutritional flavor of citrus. However, the studies on citrus metabolites by grafting with different rootstocks are very limited, especially for amino acids (AAs). The preliminary test showed that there were significant differences in total amino acid content of two rootstocks (Poncirus trifoliata (CT) and C. junos Siebold ex Tanaka (CJ)) after grafting, and total amino acid content in the peel was higher than flesh. However, the molecular mechanism affecting amino acid differential accumulation remains unclear. Therefore, this study selected peel as the experimental material to reveal the amino acid components and differential accumulation mechanism of sweet orange 'Newhall' grafted with different rootstocks through combined transcriptome and metabolome analysis. Metabolome analysis identified 110 amino acids (AAs) and their derivatives in sweet orange 'Newhall' peels, with L-valine being the most abundant. L-asparagine was observed to be affected by both developmental periods and rootstock grafting. Weighted gene co-expression network analysis (WGCNA) combined with Redundancy Analysis (RDA) revealed eight hub structural genes and 41 transcription factors (TFs) that significantly influenced amino acid biosynthesis in sweet orange 'Newhall' peels. Our findings further highlight the significance of rootstock selection in enhancing the nutritional value of citrus fruits and might contribute to the development of functional citrus foods and nutritional amino acid supplements.

Transcriptomic and metabolomic analyses provide new insights into the appropriate harvest period in regenerated bulbs of Fritillaria hupehensis

Introduction

The bulb of Fritillaria hupehensis, a traditional cough and expectorant medicine, is usually harvested from June to September according to traditional cultivation experience, without practical scientific guidance. Although steroidal alkaloid metabolites have been identified in F. hupehensis, the dynamic changes in their levels during bulb development and their molecular regulatory mechanisms are poorly understood.

Methods

In this study, integrative analyses of the bulbus phenotype, bioactive chemical investigations, and metabolome and transcriptome profiles were performed to systematically explore the variations in steroidal alkaloid metabolite levels and identify the genes modulating their accumulation and the corresponding regulatory mechanisms.

Results

The results showed that weight, size, and total alkaloid content of the regenerated bulbs reached a maximum at IM03 (post-withering stage, early July), whereas peiminine content reached a maximum at IM02 (withering stage, early June). There were no significant differences between IM02 and IM03, indicating that regenerated bulbs could be harvested appropriately in early June or July. Peiminine, peimine, tortifoline, hupehenine, korseveramine, delafrine, hericenone N-oxide, korseveridine, puqiedinone, pingbeinone, puqienine B, puqienine E, pingbeimine A, jervine, and ussuriedine levels were upregulated in IM02 and IM03, compared with IM01 (vigorous growth stage, early April). The Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the accumulation of steroidal alkaloid metabolites mainly occurred prior to IM02. HMGR1, DXR, CAS1, CYP 90A1, and DET2 may play a positive role in peiminine, peimine, hupehenine, korseveramine, korseveridine, hericenone N-oxide, puqiedinone, delafrine, tortifoline, pingbeinone, puqienine B, puqienine E, pingbeimine A, jervine, and ussuriedine biosynthesis, whereas the downregulation of FPS1, SQE and 17-DHCR may lead to a reduction in peimisine levels. Weighted gene correlation network analysis showed that CYP 74A2-1, CYP 74A2-2, CYP 71A26-1, CYP 71A26-2, and CYP74A were negatively correlated with peiminine and pingbeimine A, whereas CYP R and CYP707A1 were positively correlated. . CYP 74A2-1 and CYP 74A2-2 may play a negative role in peimine and korseveridine biosynthesis, whereas CYP R plays a positive role. In addition, the highly expressed C2H2, HSF, AP2/ERF, HB, GRAS, C3H, NAC, MYB-related transcription factors (TFs), GARP-G2-like TFs, and WRKY may play positive roles in the accumulation of peiminine, peimine, korseveridine, and pingbeimine A.

Discussion

These results provide new insights into scientific harvesting of F. hupehensis.