Pipsqueak family genes dan/danr antagonize nuclear Pros to prevent neural stem cell aging in Drosophila larval brains.

Neural stem cell aging is a fundamental question in neurogenesis. Premature nuclear Pros is considered as an indicator of early neural stem cell aging in Drosophila. The underlying mechanism of how neural stem cells prevent premature nuclear Pros remains largely unknown. Here we identified that two pipsqueak family genes, distal antenna (dan) and distal antenna-related (danr), promote the proliferation of neural stem cells (also called neuroblasts, NBs) in third instar larval brains. In the absence of Dan and Danr (dan/danr), the NBs produce fewer daughter cells with smaller lineage sizes. The larval brain NBs in dan/danr clones show premature accumulation of nuclear Prospero (Pros), which usually appears in the terminating NBs at early pupal stage. The premature nuclear Pros leads to NBs cell cycle defects and NB identities loss. Removal of Pros from dan/danr MARCM clones prevents lineage size shrinkage and rescues the loss of NB markers. We propose that the timing of nuclear Pros is after the downregulation of dan/danr in the wt terminating NBs. dan/danr and nuclear Pros are mutually exclusive in NBs. In addition, dan/danr are also required for the late temporal regulator, Grainyhead (Grh), in third instar larval brains. Our study uncovers the novel function of dan/danr in NBs cell fate maintenance. dan/danr antagonize nuclear Pros to prevent NBs aging in Drosophila larval brains.

H2S Regulation of Metabolism in Cucumber in Response to Salt-Stress Through Transcriptome and Proteome Analysis.

In a previous study, we found that H2S alleviates salinity stress in cucumber by maintaining the Na+/K+ balance and by regulating H2S metabolism and the oxidative stress response. However, little is known about the molecular mechanisms behind H2S-regulated salt-stress tolerance in cucumber. Here, an integrated transcriptomic and proteomic analysis based on RNA-seq and 2-DE was used to investigate the global mechanism underlying H2S-regulated salt-stress tolerance. In total, 11,761 differentially expressed genes (DEGs) and 61 differentially expressed proteins (DEPs) were identified. Analysis of the pathways associated with the DEGs showed that salt stress enriched expression of genes in primary and energy metabolism, such as photosynthesis, carbon metabolism and biosynthesis of amino acids. Application of H2S significantly decreased these DEGs but enriched DEGs related to plant-pathogen interaction, sulfur-containing metabolism, cell defense, and signal transduction pathways. Notably, changes related to sulfur-containing metabolism and cell defense were also observed through proteome analysis, such as Cysteine synthase 1, Glutathione S-transferase U25-like, Protein disulfide-isomerase, and Peroxidase 2. We present the first global analysis of the mechanism underlying H2S regulation of salt-stress tolerance in cucumber through tracking changes in the expression of specific proteins and genes.

H2S Alleviates Salinity Stress in Cucumber by Maintaining the Na+/K+ Balance and Regulating H2S Metabolism and Oxidative Stress Response.

Salinity stress from soil or irrigation water can significantly limit the growth and development of plants. Emerging evidence suggests that hydrogen sulfide (H2S), as a versatile signal molecule, can ameliorate salt stress-induced adverse effects. However, the possible physiological mechanism underlying H2S-alleviated salt stress in cucumber remains unclear. Here, a pot experiment was conducted with an aim to examine the possible mechanism of H2S in enhancement of cucumber salt stress tolerance. The results showed that H2S ameliorated salt-induced growth inhibition and alleviated the reduction in photosynthetic attributes, chlorophyll fluorescence and stomatal parameters. Meanwhile H2S increased the endogenous H2S level concomitant with increased activities of D/L-cysteine desulfhydrase and ß-cyanoalanine synthase and decreased activities of O-acetyl-L-serine(thiol)lyase under excess NaCl. Notably, H2S maintained Na+ and K+ homeostasis via regulation of the expression of PM H+-ATPase, SOS1 and SKOR at the transcriptional level under excess NaCl. Moreover, H2S alleviated salt-induced oxidative stress as indicated by lowered lipid peroxidation and reactive oxygen species accumulation through an enhanced antioxidant system. Altogether, these results demonstrated that application of H2S could protect cucumber seedlings against salinity stress, likely by keeping the Na+/K+ balance, controlling the endogenous H2S level by regulating the H2S synthetic and decomposition enzymes, and preventing oxidative stress by enhancing the antioxidant system under salinity stress.

[Research on relationship between occurrence of root rot and changes of fungal communities in rhizosphere of Panax quinquefolius].

The root rot disease is a common disease during the cultivation of Panax quinquefolius. In order to provide some clues for solving the root rot disease of P. quinquefolius, the relationship between rhizosphere soil fungal communities and root rot of P. quinquefolius was investigated in this study. The diversities and the changes of fungal communities structure in blank control group (group C), rhizosphere soil of healthy P. quinquefolius (group N) and occurrence of root rot in rhizosphere soil of P. quinquefolius (group R)were analyzed byusing the Illumina MiSeq high-throughput sequencing technology. A total of 505 968 high-quality sequences were obtained through high-throughput sequencing and the rare faction curves analysis showed that the sequencing depth was sufficient and the sampling was reasonable. The fungal communities structure of rhizosphere soil samples mainly belonged to 9 phylums including Ascomycota(54.9%), Basidiomycota(5.6%), etc., and the dominant specie was Ascomycota of the total fungal identified, respectively. The 115 genera of fungi were tested, including Monographella (3.9%), Archaeorhizomyces (3.9%), Mortierella, etc., and the dominant specie was Monographella. At the genus level, the abundance of Monographella and Mortierella in group R increased significantly compared with the abundance in groups C and N. Alpha diversity index of species showed that the diversity index of fungal communities reduced and the numbers of fungi reduced in group N and R, compared with group C, and reaching the minimum in group R. Beta diversity index of species showed that there was a significant difference in the fungal communities structure in each sample. In addition, the heat map analysis revealed that the dominant fungal genera were significantly different among the each sample. The proportion of Monographella and Mortierella in group R was significantly higher than that in group C and N, while the proportion of Trichoderma,Penicillium and Cadophora in group R was extremely low. The proportion of Phoma and Gibberella in group R increased significantly compared with group C. This study clarified the decline of diversity index and the imbalance of community structure in fungi may lead to the occurrence of root rot in P. quinquefolius by analysis of fungal diversity and community composition in the rhizosphere soil of P. quinquefolius in this study, which provided a theoretical basis for the prevention and treatment of occurrence of root rot in P. quinquefolius.