Microorganisms play crucial roles in maintaining ecosystem stability. The last two decades have witnessed an upsurge in studies on marine microbial community composition using high-throughput sequencing methods. Extensive mining of the compositional data has provided exciting new insights into marine microbial ecology from a number of perspectives. Both deterministic and stochastic processes contribute to microbial community assembly but their relative importance in structuring subcommunities, that are categorized by traits such as abundance, functional type and activity, differs. Through correlation-based network analysis, significant progress has been made in unraveling microbial co-occurrence patterns and dynamics in response to environmental changes. Prediction of ecosystem functioning, based on microbial data, is receiving increasing attention, as closely related microbes often share similar ecological traits and microbial diversity often exhibits significant correlations to ecosystem functioning. The ecosystem functioning is likely executed not by the whole community, but rather by an active fraction of a community, which can be inferred from the marker gene transcription level of community members. Furthermore, the huge amount of microbial community data has significantly expanded the tree of life and illuminated microbial phylogenetic divergence and evolutionary history. This review summarizes important findings in microbial assembly, interaction, functioning, activity and diversification, highlighting the interacting roles of different aspects, derived from community compositional data.
Cys2His2-like fold group (C2H2)-type zinc finger proteins promote root hair growth and development by regulating their target genes. However, little is known about their potential negative roles in root hair initiation and elongation. Here, we show that the C2H2-type zinc finger protein named ZINC FINGER PROTEIN1 (AtZP1), which contains an ERF-associated amphiphilic repression (EAR) motif, negatively regulates Arabidopsis (Arabidopsis thaliana) root hair initiation and elongation. Our results demonstrate that AtZP1 is highly expressed in root hairs and that AtZP1 inhibits transcriptional activity during root hair development. Plants overexpressing AtZP1 lacked root hairs, while loss-of-function mutants had longer and more numerous root hairs than the wild type. Transcriptome analysis indicated that AtZP1 downregulates genes encoding basic helix-loop-helix (bHLH) transcription factors associated with root hair cell differentiation and elongation. Mutation or deletion of the EAR motif substantially reduced the inhibitory activity of AtZP1. Chromatin immunoprecipitation assays, AtZP1:glucocorticoid receptor (GR) induction experiments, electrophoretic mobility shift assays, and yeast one-hybrid assays showed that AtZP1 directly targets the promoters of bHLH transcription factor genes, including the key root hair initiation gene ROOT HAIR DEFECTIVE6 (RHD6) and root hair elongation genes ROOT HAIR DEFECTIVE 6-LIKE 2 (RSL2) and RSL4, and suppresses root hair development. Our findings suggest that AtZP1 functions downstream of GL2 and negatively regulates root hair initiation and elongation, by suppressing RHD6, RSL4, and RSL2 transcription via the GL2/ZP1/ RSL pathway.
Drought and nitrogen availability are two important environmental factors that affect plant growth and the global distribution of plants. We examined the effect of nitrogen on PSII in the leaves of maize seedlings under drought stress using three nitrogen concentrations (0.5, 7.5 and 15mM) and three levels of water availability (normal conditions, mild drought and severe drought). Shoot fresh and dry weights and root fresh weight decreased with increasing drought conditions. In maize leaves subjected to drought stress, the chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, net photosynthetic rate, transpiration rate, stomatal conductance, maximum chemical efficiency (Fv/Fm), and photochemical efficiency of PSII (ΦPSII) were significantly reduced. Moderate nitrogen supply relieved the drought stress and enhanced the photosynthetic capacity. Malondialdehyde, H2O2 and O2−• accumulated in maize leaves under drought stress. Superoxide dismutase and ascorbate peroxidase activities increased in maize leaves under mild drought stress, but were significantly reduced under severe drought stress. The NO3− content and nitrate reductase (NR) activity of maize leaves were significantly reduced under drought stress, while moderate nitrogen supply promoted the accumulation of NO3− and an increase in the nitrate reductase activity. The abscisic acid content increased significantly; this increase was positively correlated with the nitrogen concentration under drought stress. Together, these results indicate that moderate nitrogen supply increases plant resistance to drought stress, while high or low nitrogen concentrations increase the sensitivity of maize to drought stress. These findings are important for guiding the agricultural use of nitrogen fertilisers.
Cytokinins promote plant growth and development under normal plant growth conditions and also play an important role in plant resistance to stress. Understanding the working mechanisms of cytokinins under adverse conditions will help to make full use of cytokinins in agriculture to increase production and efficiency of land use. In this article, we review the progress that has been made in cytokinin research in plant response to stress and propose its future application prospects.
The first one-pot enantioselective oxidative coupling of cyclic benzylic ethers with aldehydes has been developed. A variety of benzylic ethers were transformed into the corresponding oxygen heterocycles with high enantioselectivity. Mechanistic experiments were conducted to determine the nature of the reaction intermediates. The application of this strategy to coupling reactions with other nucleophiles besides aldehydes was also explored.
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