Plant Physiology and Biochemistry最新文献

Transfer RNA-derived fragments (tRFs) are noncoding small RNAs derived from transfer RNAs (tRNAs) in microorganisms, animals and plants. In plants, tRFs are known to respond to environmental stimuli, including heat, oxidative stress and UV radiation; however, their specific functions in horticultural plants, such as grapevine, remain poorly understood. In this study, we used RNA-seq to identify differentially expressed genes (DEGs) in grape leaves exposed to UV-C radiation. A total of 1329 and 8055 of genes were differentially expression after 1 and 6 h of UV-C treatment, respectively. We identified a large number of secondary metabolism-related genes in the DEGs, including genes involved in stilbene and flavonoid biosynthesis. Noticeably, the stilbene biosynthesis-related gene was induced earlier than the other genes in the phenylalanine metabolic pathway. We also conducted small RNA-seq and identified differentially expressed (DE) miRNAs and their targets. To explore whether the tRFs involved in UV-C response, further analysis of the small RNA-seq data revealed 23 down-regulated and 41 up-regulated DE tRFs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) showed that the target genes of these tRFs are involved in multiple biological processing, including hormone signal transduction and metabolite synthesis. To validate the function of tRFs, tRF39 and tRF45 were selected and overexpressed in tobacco leaves, and the expression levels of their target genes were inhibited. Our study suggests that the tRFs may regulate multiple biological processes in response to UV-C exposure in grapevine. Our findings provide a foundation for further elucidating the regulatory mechanisms of tRFs in horticultural crops.

Photosynthesis drives crop growth and production, and strongly affects grain yields; therefore, it is an ideal trait for wheat drought resistance breeding. However, studies of the negative effects of drought stress on wheat photosynthesis rates have lacked accurate evaluation methods, as well as high-throughput techniques. We investigated photosynthetic capacity under drought stress in wheat varieties with varying degrees of drought stress resistance using hyperspectral and chlorophyll fluorescence (ChlF) imaging data. We analyzed various morpho-physiological traits involved in wheat drought tolerance, including tiller number, leaf relative water content, and malondialdehyde content, to determine the relationships between drought resistance and hyperspectral and ChlF data. The results showed that the spectral first derivative ratio (FDR) between drought stress and control conditions in the 680-760 nm region was closely related to photosynthetic capacity and drought tolerance and that hyperspectral imaging can be used to monitor ChlF parameters, with bands sensitive to ChlF identified in two spectral regions (539-764 nm and 832-989 nm). The spectral first derivative at 989 nm had the strongest linear relationship with the minimal fluorescence (R² = 0.49). An uninformative variable elimination algorithm indicated that FDRs in the green (504-609 nm), red (724-751 nm), and near-infrared (944-946 nm) light regions had great potential as indices of drought resistance. A support vector machine model based on the FDRs of these characteristic bands identified wheat drought resistance with 97.33% accuracy. These findings provide insight into the application of high-throughput technologies in studying drought resistance and photosynthesis in wheat.

Desiccation is a common stress for organisms living in desert soil. Chroococcidiopsis sp. is the dominant species in the soil microbial community of desert regions. Some species of Chroococcidiopsis sp. are highly tolerant to desiccation, making them a good biological system for soil restoration in desert regions, but their adaptation mechanisms to desiccation are not well understood. In this study, different desiccation levels of desert regions were simulated in terms of relative humidity to investigate the adaptation of desert cyanobacterium Chroococcidiopsis sp. ASB-02 to desiccation. Chroococcidiopsis sp. ASB-02 exhibited the ability to rapidly restore PSII activity under desiccation-rehydration conditions. Desiccation-induced oxidative stress is a common feature and the Chroococcidiopsis sp. ASB-02 activated diverse antioxidant genes to eliminate oxidative products. When exposed to desiccation-induced water stress, Chroococcidiopsis sp. ASB-02 can slow water loss and regulate osmotic pressure by enhancing the synthesis of exopolysaccharides and intracellular sucrose. However, under extreme desiccation stress, trehalose is crucial in regulating the osmotic potential of Chroococcidiopsis sp. ASB-02. When the relative humidity is ≤ 56%, with the continuous loss of cellular water, Chroococcidiopsis sp. ASB-02 responds to reduced metabolic activity in the cell by initiating energy-saving pathways and enhancing transcription mechanisms. This study provides a theoretical basis for understanding the adaptation mechanisms of desert cyanobacterium Chroococcidiopsis sp., which is important for soil restoration in desert regions.

Citrus bacterial canker has deleterious effects on global citrus production. The mitogen-activated protein kinase (MAPK) signaling cascade regulates plant defense against pathogen infection. Here, we identified 11 MAPKs in Atalantia buxifolia, a wild citrus species with high stress tolerance. Phylogenetic and gene structure analysis of the identified MAP kinases (MPKs) was conducted, and conserved motifs were identified. MPK expression was altered in Xanthomonas citri subsp. citri (Xcc)-resistant Atalantia buxifolia and Xcc-sensitive sweet orange after Xcc infection. AbMPK13 expression was significantly up-regulated after Xcc infection. AbMPK13 was localized to the cytoplasm, and its overexpression enhanced the resistance of sweet orange to Xcc and activated the salicylic acid (SA) signaling pathway. These findings clarify the role of MPKs in the citrus canker resistance of A. buxifolia.

Pepper (Capsicum annuum L.) is one of the most significant vegetable crops worldwide which is known for its pungency and nutritional value. The aldehyde dehydrogenase (ALDH) superfamily encompasses enzymes critical for the detoxification of toxic aldehydes into non-toxic carboxylic acids. A comprehensive genome-wide approach in pepper identified a total of 27 putative ALDH genes grouped into ten families based on the criteria of the ALDH gene nomenclature committee. Both segmental and tandem duplication assisted in the enhancement of CaALDH gene family members. The identified CaALDH members were found to be more closely related to the dicot plants, however, the members were distributed across the phylogenetic tree suggesting the pre-eudicot-monocot separation of the ALDH superfamily members. The gene structure and protein domain were found to be mostly conserved in separate phylogenetic classes, indicating that each family played an important role in evolution. Expression analysis revealed that CaALDHs were expressed in various tissues, developmental stages, and in response to abiotic stresses, indicating that they can play roles in plant growth, development, and stress adaptation. Interestingly, the majority of the CaALDH genes were found to be highly responsive to salinity stress, and only the CaALDH11A1 transcript showed upregulation in cold stress conditions. The presence of cis-acting elements in the promoter region of these genes might have a significant role in abiotic stress tolerance. Overall, these findings add to the current understanding, evolutionary history, and contribution of CaALDHs in stress tolerance, and smooth the path of further functional validation of these genes.

As a new plant hormone, strigolactone not only promotes leaf senescence, inhibits plant branching and regulates root structure, but also plays an important role in abiotic stress resistance. However, little is known about the function of VvCCD7 under abiotic stress, a key gene for the synthesis of strigolactone in grapevine. In this study, VvCCD7 gene was cloned from grape leaves of 'Cabernet Sauvignon'. In Arabidopsis, the function of VvCCD7 was verified under drought and low phosphorus stress. The open reading frame of VvCCD7 is 1833 bp in length, encoding 610 amino acids, and the expression level was the highest in the old leaves. Under drought stress, the leaves of wild-type Arabidopsis yellowed and withered, the leaves of overexpressed Arabidopsis shrank slightly, and the peroxidase activity and proline content were significantly higher than those of wild-type Arabidopsis. The expression of AtBzip17 and AtVOZ2 in overexpressed Arabidopsis was significantly higher than that in the wild type, and the expression of AtCOR15A was significantly lower than that in the wild type. Under low phosphorus stress, the growth of wild-type Arabidopsis was slowed down and its root elongation was inhibited. The growth of overexpressed Arabidopsis was healthy and its root elongation was normal. In conclusion, VvCCD7 gene enhanced the tolerance of Arabidopsis to drought and low phosphorus stress, which laid a foundation for further study on the abiotic stress-relieving mechanism of strigolactone.

Cytochrome P450 enzymes (CYPs), the members of the largest superfamily of enzymes in plant kingdom, catalyze a variety of functional group transformations involved in metabolite biosynthesis, end-product derivatization, and exogeneous molecule detoxification. Nevertheless, CYPs' functional characterization and practically industrial application have been largely encumbered by their critical dependency on the reducing equivalent for the catalytic cycling, driven by the tedious electron relay mediated by CYP reductase (CPR). Here, we report a photoinduced electron transfer system that initiates and sustains the CYP-catalyzed reaction cycling. Using Camptotheca acuminata CYP72A565-catalyzed carbon-carbon cleavage reaction, a key biosynthetic reaction in the biosynthesis of plant-derived antitumor monoterpene indole alkaloid camptothecin, as a representative CYP-catalyzed reaction model, we identified eosin Y (EY) and triethanolamine (TEOA) as an efficient photosensitizer/sacrificial reagent pair for the photoinduced electron generating system. The C. acuminata camptothecin 10-hydroxylase-catalyzed regioselective C10-hydroxylation of camptothecin into 10-hydroxycamptothecin could be enabled by the photoinduced electron transfer system, demonstrating that the EY/TEOA pair serves as an efficient surrogate for membranous CPR and can be expanded to other CYP-catalyzed reaction cycling. The catalytic efficiency of the photoinduced electron transfer-driven CYP-catalyzed cycling exceeds that of the native NADPH-dependent CPR-supported CYP-catalyzed reaction, thereby circumventing the dependency on both NADPH and the reductase CPR. The present study provides a photoinduced electron generating and transferring system as an efficient and facile alternative to membranous NADPH-dependent CPR, offering a new avenue for CYP-mediated conversion of complex bioactive natural products using synthetic biology approaches.

High temperature stress leads to a dramatic reduction of both the anthocyanin concentration and the appearance quality of colored potatoes. However, it remains uncertain if the high temperature impacts potato tuber skin coloring through only the aerial or belowground parts of the plant, or through their interaction; and it's underlying reason is still unclear. In this study, the red-skin cultivar Qingshu9 (Qs9) was exposed to the high-temperature (30 °C) treatment on the belowground part alone (BH), aerial part alone (AH) and entire plant (EH), and the normal-temperature treatment on entire plant (EN) as control. The results indicated that the total anthocyanin content in tuber skin of the BH treatment was significantly lower than the EN and AH treatment, and there was no accumulation of cyanidin and pelargonidin in BH treatment, only peonidin. Compared with the EN treatment, the decrease rate of total anthocyanin content of the AH treatment was much smaller than the BH treatment, and the composition of anthocyanin did not change. Transcriptome analysis showed the downregulated DEGs of BH vs EN, BH vs AH and AH vs EN were significantly associated with the anthocyanin synthesis and metabolism pathway. High temperature inhibited anthocyanin synthesis by reducing the expression of key genes (StPAL, StF3H, StF3'H, StF3'5'H, StDFR and StANS) in the anthocyanin synthesis pathway. In summary, high temperature inhibits anthocyanin synthesis in tuber skin by downregulating key genes, and this inhibitory effect mainly occurs through the belowground part of the plant.

Owing to the scarcity of cultivable land in China, the agricultural sector is primarily focused on grain and oil crops. Simultaneously, the cultivation of cotton has gradually shifted towards regions characterized by elevated soil salinity levels. Additionally, the mechanism behind cotton's ability to tolerate salt remains elusive. In this study, we identified the Z9807 genotype as highly tolerant to salt stress, exhibiting superior leaf wilting resistance, antioxidant activity, catalase activity, K⁺/Na⁺ ratio, and growth compared to the salt-sensitive ZJ0102. Comparative transcriptome analysis revealed marked differences in salt stress responses between Z9807 and ZJ0102. This study identified a considerable number of differentially expressed genes associated with salt tolerance across multiple time points. By integration of QTL and GWAS mapping data, we successfully identified 621 candidate genes associated with salt tolerance. Weighted gene correlation network analysis exhibited three co-expression modules related to salt-tolerant Z9807 samples, ultimately identifying 15 core salt-tolerant candidate genes. We also conducted in-depth research on the salt tolerance of the stress-associated protein (SAP) GhSAP6 (GhSAP6_At and GhSAP6_Dt homologs). Results revealed that these candidate genes may inhibit salt tolerance through Virus-Induced Gene Silencing (VIGS) and transgenic overexpression assays conducted in Arabidopsis thaliana. Furthermore, we used yeast two-hybrid and luciferase assay experiments to confirm the ubiquitin degradation pathway between selected interacting proteins and verified the interaction with RAD23C. This study will provide new insights into the mechanisms related to salt tolerance in upland cotton.

Paeonia suffruticosa is a plant of Paeonia in Paeoniaceae. It is an important woody ornamental flower in the world. High temperature in summer hinders the growth of tree peony and reduces its ornamental quality, which restricts the cultivation and application of tree peony in Jiangnan area of China. Paeonia suffruticosa 'Hu Hong' is a traditional Chinese tree peony variety with high ornamental value. It is an excellent parent material for cultivating heat-resistant peony. This paper selected the tree peony variety 'Hu Hong' as the material. The transcriptome data of Paeonia suffruticosa 'Hu Hong' at 0, 2, 6, 12 and 24 h after high temperature treatment were analyzed by RNA-Seq method. At each time point, a large number of significantly differentially expressed genes(DEGs) were screened between tree peony cultured at high temperature and room temperature. The analysis of the common DEGs in the four comparison groups showed that the differential genes were mainly enriched in the GO terms ' protein processing in endoplasmic reticulum', 'Pentose and glucuronate interconversions ', ' plant-pathogen interaction ', ' zeatin biosynthesis ', ' fatty acid elongation ', and ' plant hormone signal transduction ' pathways. Abscisic acid(ABA), ethylene(ET) and brassinosteroid(BR) signaling related genes were significantly up-regulated in 'Hu Hong' to resist high temperature treatment. In the auxin(IAA), cytokinin(CTK), gibberellin(GA), salicylic acid(SA) pathways, compared with the control group, the down-regulated expression was involved in hormone signal transduction to respond to high temperature treatment. A total of 62 TFs from 28 different families were annotated, with the AP2/ERF family annotating the largest number. Among the TFs annotated to the AP2/ERF family, the highest expression gene PsDREB2A was found. Overexpression of PsDREB2A Arabidopsis plants improved heat tolerance under high temperature treatment. However, silencing PsDREB2A in tree peony resulted in a heat-intolerant phenotype. PsDREB2A can directly bind to the DRE-core motif in the PsHSFA3 promoter to initiate its expression. In addition, PsHSFA3-overexpressing plants showed higher heat resistance, while PsHSFA3-silenced plants showed lower heat resistance. This study provides a scientific basis for in-depth study of the molecular mechanism of high temperature treatment response in tree peony, improving the heat signal transduction regulation network of tree peony, and mining heat-resistant related genes.