Plant, Cell & Environment最新文献

Plant water transport is essential to maintain turgor, photosynthesis and growth. Water is transported in a metastable state under large negative pressures, which can result in embolism, that is, the loss of function by the replacement of liquid xylem sap with gas, as a consequence of water stress. To avoid experimental artefacts, we used an optical vulnerability system to quantify embolism occurrence across six fully expanded maize leaves to characterize the sequence of physiological responses (photosynthesis, chlorophyll fluorescence, whole-plant transpiration and leaf inter-vein distance) in relation to declining water availability and leaf embolism during severe water stress. Additionally, we characterize the recovery of leaf function in the presence of sustained embolism during a 6-day recovery period. Embolism formation occurred after other physiological processes were substantially depressed and were irreversible upon rewatering. Recovery of transpiration, net CO₂ assimilation and photosystem II efficiency were aligned with the severity of embolism, whereas these traits returned to near pre-stress levels in the absence of embolism. A better understanding of the relationships between embolism occurrence and downstream physiological processes during stress and recovery is critical for the improvement of crop productivity and resilience.

Phenotypic plasticity is the property of an organism to change in response to different environments. Understanding and leveraging crop phenotypic plasticity is crucial for mitigating threats caused by climate change. Here, we assessed phenotypic plasticity in multi-environment trials over 4 years, using 505 inbred lines from a Brassica napus genetic diversity panel. The variation in seed oil content (SOC) plasticity was primarily associated with three environmental indices: precipitation, diurnal temperature range, and ultraviolet B during the flowering or pod-filling stage, alongside five major plasticity genes. Leveraging this information with climate records, we developed a predictive model to estimate SOC for various planting dates in seven major production regions and validated our predictions in new environments. As climate change necessitates new breeding materials with improved genetics, we examined the genetic potentials of existing lines for enhanced SOC in future climates. Using projected environmental data and the identified major plasticity genes, we predicted SOC of genotypes across production regions. We also identified an optimal haplotype, a specific combination of alleles, for each production region to sustainably produce high SOC for future climates. This study offers insights and selection methods that contribute to mitigating the adverse effects of climate change on agriculture.

Ubiquitin-mediated proteolysis is a crucial mechanism in plant defenses against pathogens. However, the role of E3 ubiquitin ligases in the maize (Zea mays) defense response against Rhizoctonia solani, a major soil-borne fungal pathogen that causes banded leaf and sheath blight, remains unclear. We previously identified the maize ZmPUB19 gene, which encodes a U-box E3 ubiquitin ligase and is upregulated upon R. solani infection, suggesting its potential involvement in maize defense responses. In this study, we established that ZmPUB19 positively influences the maize defense response to R. solani. In vitro and in vivo experiments revealed that ZmPUB19 interacts with and ubiquitinates the mitogen-activated protein kinase ZmMPK5, resulting in ZmMPK5 degradation in response to R. solani infection. The Zmmpk5 mutant demonstrated superior resistance to R. solani compared to the wild type. Additionally, we identified an AT-Hook Motif Nuclear Localized (AHL) transcription factor, ZmAHL25, which binds to the AT-rich cis-element in the ZmPUB19 promoter and activates its expression under R. solani attack. Notably, decreased expression of ZmAHL25 increased maize susceptibility to R. solani. Collectively, our findings show that the ZmAHL25-ZmPUB19-ZmMPK5 module plays a positive role in regulating maize defense responses to R. solani infection.

Glycosyltransferase genes are organised as tandem repeats in the buckwheat genome, yet the functional implications and evolutionary significance of duplicated genes remain largely unexplored. In this study, gene family analysis revealed that FtUGT71K6 and FtUGT71K7 are tandem repeats in the buckwheat genome. Moreover, GWAS results for epicatechin suggested that this tandem repeat function was associated with epicatechin content of Tartary buckwheat germplasm, highlighting variations in the promoter haplotypes of FtUGT71K7 influenced epicatechin levels. FtUGT71K6 and FtUGT71K7 were shown to catalyse UDP-glucose conjugation to cyanidin and epicatechin. Furthermore, overexpression of FtUGT71K6 and FtUGT71K7 increased total antioxidant capacity and altered metabolite content of the epicatechin biosynthesis pathway, contributing to improved drought tolerance, while overexpression of FtUGT71K6 significantly improved salt stress tolerance. However, overexpression of these two genes did not contribute to resistance against Rhizoctonia solani. Evolutionary selection pressure analysis suggested positive selection of a critical amino acid ASP-53 in FtUGT71K6 and FtUGT71K7 during the duplication event. Overall, our study indicated that FtUGT71K6 and FtUGT71K7 play crucial roles in drought stress tolerance via modulating epicatechin synthesis in buckwheat.

Our aim was to elucidate mechanisms underlying nitrogen (N)-deficiency tolerance in bread wheat (cultivar Ruta), conferred by a wild emmer wheat QTL (WEW; IL99). We hypothesised that the tolerance in IL99 is driven by enhanced N-uptake through modification of root system architecture (RSA) underscored by transcriptome modifications. Severe N-deficiency (0.1 N for 26 days) triggered significantly higher plasticity in IL99 compared to Ruta by modifying 16 RSA traits; nine of which were IL99-specific. The change in root growth in IL99 was collectively characterised by a transition in root orientation from shallow to steep, increased root number and length, and denser networks, enabling nutrient acquisition from a larger volume and deeper soil layers. Gene ontology and KEGG-enrichment analyses highlighted IL99-specific pathways and candidate genes elevated under N-deficiency. This included Jasmonic acid metabolism, a key hormone mediating RSA plasticity (AOS1, TIFY, MTB2, MYC2), and lignification-mediated root strengthening (CYP73A, 4CL). 'N-metabolism' was identified as a main shared pathway to IL99 and Ruta, with enhanced nitrate uptake predominant in IL99 (NRT2.4), while remobilisation was the main strategy in Ruta (NRT2.3). These findings provide novel insights into wheat plasticity response underlying tolerance to N-deficiency and demonstrate the potential of WEW for improving N-uptake under suboptimal conditions.

Soluble sugars provide energy sources required for plant growth and development. They also act as osmoprotectants to improve the salt tolerance of plants. However, molecular mechanism underlying the negative regulation of soluble sugar accumulation in plants under salt stress conditions remains unknown. In this study, we investigated the functions of ankyrin-repeat kinase 2 (ANK-PK2) that regulates soluble sugar content in Arabidopsis under salt stress. ANK-PK2 interacts with and phosphorylates the sugar transporter protein 11 (STP11) under salt stress. Phosphorylated STP11 is easier to degrade, and its glucose-transporting ability and soluble sugar accumulation are inhibited. The ank-pk2 mutant exhibited increased salt tolerance. The salt-sensitive phenotype of the mutant stp11 was recovered through a dephosphorylation mutation that changed Thr²²⁷ in STP11 to Ala²²⁷. Our results revealed a novel molecular mechanism underlying salt stress adaptation in Arabidopsis, which ANK-PK2 negatively regulates salt tolerance by phosphorylating and subsequently decreasing the transport activity of STP11 to balance the cellular soluble sugar content in Arabidopsis.

Tomato yellow leaf curl virus (TYLCV) is a significant threat to tomato cultivation globally, transmitted exclusively by the whitefly Bemisia tabaci. While previous research suggests that the TYLCV C2 protein plays a role in fostering mutualistic interactions between the virus and its insect vectors, the specific mechanisms remain unclear. In this study, we show that the C2 protein interferes with the salicylic acid (SA) defence pathway by disrupting TCP7-like transcription factor-mediated regulation of TGA2 expression. Whitefly infestation increases the expression of TCP7-like transcription factors (TCP7-L1 and TCP7-L2), which subsequently trigger TGA2-dependent activation of BGL2 transcription, enhancing plant resistance to whiteflies. However, the TYLCV C2 protein interacts with these TCP7-like factors, reducing their binding affinity to the TGA2 promoter, which in turn suppresses BGL2 expression in the SA signalling pathway. These findings provide new insights into how TYLCV C2 modulates TCP7-like protein activity to impair SA-mediated defences, contributing to the mutualistic relationship between TYLCV and whiteflies. This work deepens our understanding of the complex regulatory networks underlying these virus-vector-host interactions.

In natural environments, the growth and development of trees are continuously affected by phosphorus (P) starvation stress. However, the mechanisms through which trees balance stem growth and P distribution remain unknown. This study found that in the woody model species poplar, the P loss in stems is more severe than that in roots and leaves under P starvation conditions, thereby inhibiting stem development and reducing the expression of numerous genes related to wood formation, including PagSND1-B1. Intriguingly, overexpression of PagSND1-B1 in poplar enhances resistance to P starvation and promotes xylem development. Further analysis demonstrated that PagSND1-B1 can directly and positively regulate the phosphorus transporter PagPHT1;5a. Analysis of P content changes in leaves, stems and roots of transgenic poplar before and after treatment indicated that overexpression of PagSND1-B1 disrupts the normal P redistribution procedure, leading to increased P accumulation in stems, which is beneficial for xylem development. Therefore, PagSND1-B1 participates in the phosphorus absorption and homoeostasis of poplar by modulating PagPHT1;5a. This study provides valuable insights into the regulatory function of PagSND1-B1 in wood formation and the process by which trees balance phosphorus distribution and xylem development.

Bacillus velezensis SQR9 or Trichoderma harzianum NJAU4742-amended bioorganic fertilizers might significantly improve the soil microbial community and crop yields. However, the mechanisms these microorganisms act are far away from distinctness. We combined amplicon sequencing with culturable approaches to investigate the effects of these microorganisms on pear tree growth, rhizosphere nutrients and microbial mechanisms. The SQR9 and T4742 treatments increased the total biomass of pear trees by 68% and 84%, respectively, compared to the conventional organic fertilizer treatment (CK). SQR9 tends to increase soil organic matter and available phosphorus, while T4742 more effectively enhances nitrogen, potassium, iron and zinc levels. These effects were primarily linked to changes in the microbial community. T4742 treatment enriched twice as many differential microbes as SQR9. SQR9 significantly enriched Urebacillus, Streptomyces and Mycobacterium, while T4742 increased the abundance of Pseudomonas, Aspergillus and Penicillium. In vitro experiments revealed that secondary metabolites secreted by B. velezensis SQR9 and T. harzianum NJAU4742 stimulate the growth of key probiotics associated with their respective treatments, enhancing soil fertility and plant biomass. The study revealed the specific roles of these bioorganic fertilizers in agricultural applications, providing new insights for developing effective and targeted bioorganic fertilizer products and promoting sustainable agriculture.