生命科学最新文献

Salt stress is a major abiotic stress restrict plant growth and distribution. In our previous study, we found the ABI5-BINDING PROTEIN 2a (PagAFP2a) gene was rapidly and significantly induced by salt stress in hybrid poplar (Populus alba × Populus glandulosa), however, its function in salt stress responses was unclear. In this study, we further demonstrated that the PagAFP2a gene expression is significantly induced by salt and ABA treatments. Additionally, the ABA-responsive element (ABRE) binding proteins (PagAREB1s) directly bind to PagAFP2a promoter and activate its expression. Physiological analysis showed that PagAFP2a overexpression (PagAFP2aOE) or PagAREB1-3 knockout (PagAREB1-3KO) significantly reduced salt tolerance whereas PagAFP2a knockout (PagAFP2aKO) or PagAREB1-3 overexpression (PagAREB1-3OE) significantly enhanced salt tolerance in poplar. Correspondingly, salt stress responsive genes were significantly upregulated in PagAFP2aKO and PagAREB1-3OE plants while downregulated in PagAFP2aOE and PagAREB1-3KO plants. Furthermore, we demonstrated that PagAFP2a directly interacts with PagAREB1s and represses its transcriptional activity at the target genes. In summary, our results unveil the PagAFP2a-PagAREB1s module form a negative feedback loop in ABA signaling to fine-tune salt stress responses in Populus.

Seed dormancy is an adaptive trait that delays germination until environmental conditions become favorable for seedling survival and growth. Germination has been shown to depend on the mechanical resistance strength of the covering layers (testa and endosperm) that counteracts the growth force of the embryo. Cell wall remodeling is essential in the regulation of germination processes. In Arabidopsis thaliana, the side chain trimming of xyloglucans (XyG), the major hemicellulose in cell walls, by the apoplastic XYLOSIDASE1 (XYL1), has been previously shown to regulate XyG side chain length and seed dormancy. To investigate to what extent side chain complexity impacts on cell wall mechanical properties and regulates seed germination, xyl1 mutations were combined here with mutations in the two other glycosidases, the fucosidase AXY8 and the beta-galactosidase BGAL10. Analysis of germination phenotypes in axy8 bgal10 xyl1 and in several XyG biosynthesis mutants did not show any link between dormancy depth and side chain length. The very specific effect of xyl1 on seed dormancy in single and multiple mutants was clearly correlated with alterations in XyG intracellular localization, together with release and oxidation of free oligosaccharides (XGO). Accumulation of oxidized XGO could negatively impact cell wall remodeling by impairing remobilization and polarized secretion in cell walls, thus reducing growth anisotropy in elongating organs and modifying mechanical characteristics in seed tissues.

Soil salinity severely restricts crop quality and yields. Plants have developed various strategies to alleviate salinity stress's negative effects, including polyamine redistribution by polyamine uptake transporters (PUTs). However, the mechanisms by which PUTs alter polyamine translocation processes during salt stress have not been fully elucidated. Here, we show that disruption of PUT2, which is involved in polyamine shoot-to-root transport, results in salt sensitivity phenotypes in tomato. Moreover, yeast one-hybrid screened for an HD-Zip transcription factor HB52 that interacts with PUT2, and loss of function of HB52 also led to increased sensitivity to salt stress, whereas HB52-overexpression lines exhibited improved salt tolerance. Furthermore, molecular analyses demonstrated that HB52 directly activated the expression of PUT2 and facilitated Na⁺ efflux by promoting polyamine shoot-to-root mobility. This study uncovers a synergistic transcriptional regulatory network associated with a homeobox protein regulator that promotes polyamine long-distance transport under salt stress.

Heading date and panicle architecture are pivotal traits that significantly influence rice yield. Here, we identified a gene OsCCT23 encoding a CCT domain-containing protein that delays heading by over 40 days and increases grain yield by 60-104% through overexpressing. Two types transcripts OsCCT23L and OsCCT23S were isolated by 5'RACE, and transgenic events demonstrated that the effect of the predominant transcript OsCCT23S, encoding an 81-aa protein without the B-box domain, is comparable to OsCCT23. OsCCT23 is predominantly expressed in leaves and follows a diurnal expression pattern with a peak at dawn. Overexpressing OsCCT23 upregulated the floral repressor Ghd7 and downregulated the floral inducer RID1, consequently led to the downregulation of Ehd1, Hd3a and RFT1. Additionally, it regulates the expression of certain circadian clock-related genes, including OsGI and OsTOC1. RNA in situ hybridisation analysis confirmed that OsCCT23 activates the expression of Ghd7 in the panicle branch meristem. OsCCT23 suppresses the expression of four OsCKX genes including Gn1a, which associate with cytokinin accumulation in panicles. Natural variation in OsCCT23 promoter identified by eGWAS associates its mRNA abundance and rice heading date. Consequently, OsCCT23 substantially delays heading and significantly increases grain yield, making it highly valuable for rice breeding.

Fitting mechanistic models, such as the Farquhar-von-Caemmerer-Berry model, to experimentally measured photosynthetic CO₂ response curves (A-C_i curves) is a widely used technique for estimating the values of key leaf biochemical parameters and determining limitations to photosynthesis in vivo. Here, we present PhotoGEA, an R package with tools for C₃ A-C_i, C₃ Variable J and C₄ A-C_i curve fitting. In contrast to existing software, these automated tools use derivative-free optimizers to ensure close fits and they calculate non-Gaussian confidence intervals to indicate which parameter values are most reliable. Results from PhotoGEA's C₃ A-C_i curve fitting tool are compared against other available tools, where it is found to achieve the closest fits and most reasonable parameter estimates across a range of curves with different characteristics. PhotoGEA's C₃ Variable J and C₄ A-C_i fitting tools are also presented, demonstrating how they can provide insights into mesophyll conductance and the processes limiting C₄ photosynthesis at high CO₂ concentrations. PhotoGEA enables users to develop data analysis pipelines for efficiently reading, processing, fitting and analysing photosynthetic gas exchange measurements. It includes extensive documentation and example scripts to help new users become proficient as quickly as possible.

Dormancy is a critical adaptive feature for trees to respond effectively to environmental changes. Understanding the comprehensive mechanisms regulating dormancy in poplar is vital for the genetic improvement of forest trees. However, previous studies have typically used mixed-sample extraction, which fail to capture spatial tissue-specific responses. This study provides precise spatial lipidomics analysis of poplar buds during phases of growth and dormancy by employing an innovative technique combining liquid chromatography-tandem mass spectrometry with matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) for precise spatial lipidomics analysis of poplar buds during phases of growth and dormancy. MALDI-MSI revealed that most phospholipids were uniformly distributed across all tissues in growing buds but localized in the bud axis during dormancy. Moreover, triacylglycerols, which serve a storage function, were observed to accumulate mainly within the shoot apical meristem tissue during dormancy. These findings highlight the unique spatial distribution patterns of lipids during bud growth and dormancy in poplar, emphasize the role of lipid metabolism in adapting to seasonal changes, and provide new approach for elucidating the lipidomics of seasonal growth patterns in trees.

Nitrogen (N) fertilisers increase crop yields; however, excessive application reduces nitrogen use efficiency (NUE) and causes environmental pollution, highlighting the urgent need for sustainable agricultural practices. This study investigated the response of tiller-related traits to nitrogen availability during barley domestication and breeding, aiming to identify genetic resources with high NUE. A total of 305 barley accessions were analyzed under two nitrogen levels, focusing on six tiller-related traits and their relationship with nitrogen supply. Domestication reduced tillers per plant (TPP) and nonproductive tillers per plant (NTPP), while breeding increased spikes per plant (SPP), proportion of productive tillers (PPT), and Spike-response to nitrogen (SRN). SRN was used as a key indicator to evaluate spike development under varying nitrogen conditions. Genome-Wide Association Study (GWAS) and RNA-seq analysis identified HvNLP4 as a key candidate gene regulating SRN, with haplotype analysis revealing that HvNLP4^Hap1, associated with high SRN, underwent strong positive selection during domestication and breeding. Moreover, HvNLP4^Hap1 exhibited weaker induction under low nitrogen conditions, suggesting that avoiding its selection in future breeding programmes may enhance NUE in barley. These findings provide valuable insights for developing sustainable barley cultivars with improved nitrogen efficiency.