Plant, Cell & Environment最新文献

Catalpa bungei is a highly valued timber species renowned for its superior wood properties. However, the development of tension wood (TW) induced by wind and other mechanical stresses during the growing season significantly reduces its economic value. Although Homeodomain Leucine Zipper (HD-Zip), a plant-specific transcription factor family, has been reported to play various roles in plant growth, development, and stress resistance, a systematic characterisation of the HD-Zip gene family in C. bungei, particularly regarding the regulatory mechanisms involved in TW formation, is still lacking. Here, we identified a total of 48 HD-Zip genes (Cbuhdzs) in C. bungei and analysed their phylogeny, structure, and expression profiles. In particular, Cbuhdz34, a member of the HD-Zip I subfamily, was specifically upregulated during TW formation. To further explore its function, we overexpressed Cbuhdz34 (OE-Cbuhdz34) in poplar '84 K', which led to noticeable changes in plant growth and fibre cell length. Moreover, compared with wild-type plants, the OE-Cbuhdz34 plants presented increased TW formation under bending stress, as indicated by increased TW width, gelatinous layer width, and eccentric growth rate, suggesting a positive regulatory role in TW formation. Additionally, hierarchical genetic regulatory network analysis revealed the direct targets of Cbuhdz34, including CbuMYB63 and three genes involved in cell wall synthesis (CbuGATL1, CbuFLA17, and CbuLRR14). Further, yeast one-hybrid and dual-luciferase reporter assays confirmed the activation of these targets by Cbuhdz34. In conclusion, our results provide insights into the molecular mechanisms by which Cbuhdz34 regulates TW formation and lay a genetic foundation for the potential improvement of wood quality in C. bungei.

Leaf morphology is crucial for plant photosynthesis and stress adaptation. While CIN-like TCP transcription factors are well-known for their roles in leaf curling and morphogenesis, the function of CYC-like TCPs in leaf development remains largely unexplored. This study identifies CmCYC2d as a key regulator of abaxial leaf curling in Chrysanthemum morifolium. Phenotypic analysis revealed that the downward curling observed in OX-CmCYC2d transgenic lines was primarily due to the enlargement of adaxial epidermal cells. Furthermore, a reduction in epidermal cell number was identified as a significant contributor to the smaller leaf area in these plants. Transcriptome and WGCNA analyses highlighted CmSAUR55 as a potential downstream target of CmCYC2d. ChIP-qPCR, EMSA, and LUC assays confirmed that CmCYC2d directly bound to the CmSAUR55 promoter. Additionally, transcriptome data revealed that the reduced cell number in OX-CmCYC2d transgenic lines may be mediated by auxin-related pathways and key genes such as CNR7. The CmCYC2d-CmSAUR55 module was also closely linked to the development of enlarged adaxial epidermal cells in the leaf sinus, emphasising its role in this developmental process. This study highlights the regulatory role of CmCYC2d in leaf development and sheds light on the molecular mechanisms underlying leaf curling in chrysanthemum.

The efficacy of Taxol, a natural anticancer drug, in the treatment of various types of cancers has been certified globally. Fungal elicitors have been reported as an impressive strategy for enhancing Taxol biosynthesis. We have investigated the effect of twig age on Taxol biosynthesis and the communities of endophytic fungi. A negative correlation between Taxol content and the complexity of the endophytic fungal community in twigs was predicted. Endogenous taxoids, similar to balancing valves, might have a specific effect on controlling the microbiota assembly in Taxus twigs. Utilising the special correlation, 11 isolates of twig age-associated fungi were used to screen new fungal elicitors involved in Taxol biosynthesis. Two efficient fungal elicitors, L01 (Guignardia) and J02 (Diaporthe), were identified, increasing the Taxol contents by 5.91- and 4.83-folds, respectively. It is confirmed that effective fungal elicitors may be negatively correlated with Taxol contents in Taxus tissues. Furthermore, the J02 and L01 fungal elicitors significantly induced the jasmonic acid (JA) content, speculating the involvement of MYC2a-controlled JA signalling in fungal elicitor-activated Taxol biosynthesis. Our data revealed the effect of twig age on Taxol biosynthesis of Taxus and provided a novel approach to screen effective fungal elicitors involved in Taxol biosynthesis.

Insect symbiotic microbiota acting as a third-party force of plant-insect interactions, play a significant role in insect hosts tolerance to phytochemical defences. However, it remains unknown whether insect symbiotic bacteria can assist the host in degrading phytochemical defences induced by egg deposition. Plagiodera versicolora is a worldwide forest pest. Our study showed that P. versicolora egg deposition on Populus davidiana × Populus bolleana induced significant changes in the transcriptome and metabolome of leaves. Combined qRT-PCR and LC-MS quantitative analysis of metabolic pathways showed that the contents of chlorogenic acid and rutin were significantly increased upon egg deposition in poplar. Bioassays indicated that the high concentration of chlorogenic acid induced by egg deposition could significantly reduce the performance of germ-free larvae. Six symbiotic bacterial strains with potential ability to degrade chlorogenic acid were isolated and identified. Their degradation products did not affect larval survival either. In vivo inoculation assays showed that four of those symbiotic bacteria could assist in the degradation of high concentration of chlorogenic acid induced by egg deposition and improve the larval survival. Our study provides clear evidence that the insect symbiotic bacteria can mediate the tolerance of herbivorous insects against plant toxins induced by egg deposition.

Decapping 5'-3' exoribonucleases from the DXO/Rai1 family are highly conserved among eukaryotes and exhibit diverse enzymatic activities depending on the organism. The biochemical and structural properties of the plant DXO1 differ from the yeast and animal counterparts, which is reflected in the in vivo functions of this enzyme. Here we show that Arabidopsis DXO1 contributes to the efficient processing of rRNA precursors in both nucleolar/cytosolic and chloroplast maturation pathways. However, the processing defects in DXO1-deficient plants do not depend on the catalytic activity of the enzyme but rely on its plant-specific N-terminal extension, which is responsible for the interaction with the mRNA cap methyltransferase RNMT1. Our RNA sequencing analyses show that the dxo1 mutation deregulates the expression of many ribosomal protein genes, most likely leading to inefficient or delayed pre-rRNA maturation. These phenotypes are partially suppressed by RNMT1 overexpression, suggesting that defective cap synthesis may be responsible, at least to some extent, for the observed effects.

Drought significantly restricts the growth and quality of fruit trees Prunus mira, an ancient wild peach species, exhibits strong drought tolerance; however, the detailed response mechanism remains unknown. The nucleic acid excision repair factor radiation sensitivity 23d (Rad23d) plays a crucial role in plant stress, growth, and development. However, its specific mechanism of action in P. mira is unclear. Here, we report that PmRad23d positively contributes to the abscisic acid (ABA)-dependent drought response in P. mira. Overexpression of PmRad23d enhanced drought tolerance and ABA sensitivity, whereas inhibiting PmRad23d expression reduced the plant's drought tolerance and ABA sensitivity. PmRad23d was found to interact with the C2 domain at the N-terminus of PmSRC2 and PmCAR4, respectively. Together, they regulate the expression of ABA- and drought-related genes, activate ABA signaling, and induce stomatal closure, ultimately enhancing drought resistance in plants. Our findings shed light on the ABA-dependent drought response mechanism of PmRad23d, providing a basis for further exploration of drought tolerance in P. mira. Additionally, this study identifies potential candidate genes for enhancing peach germplasm resources and breeding drought-tolerant cultivars.

Plant hormones are pivotal in orchestrating diverse aspects of growth and developmental processes. Among various phytohormones, auxin and salicylic acid (SA) stand out as important regulators, often exerting opposing effects on overall plant growth. Essentially, research has indicated that auxin and SA-mediated pathways exhibit mutual antagonism during pathogen challenge. Additionally, in recent years, significant advancements have been made in uncovering the molecular intricacies that govern the action and interplay between these two phytohormones during various essential growth-related processes. In this discussion, we briefly delve into the genetic and molecular mechanisms involved in auxin and SA antagonism. We then analyse in detail how this dialogue impacts critical aspects of root development, with an emphasis on the transcriptional and protein regulatory networks. Finally, we propose the potential of exploring their interaction in various other aspects of below ground root growth processes. Understanding this relationship could provide valuable insights for optimizing and enhancing crop growth and yields.

Lignified stone cell content is one of the critical factors affecting 'Dangshansuli' fruit quality. The function of MADS-box transcription factors in regulating lignin biosynthesis in pear fruit is still less. In this study, PbMADS49 gene silencing inhibited the lignin biosynthesis and stone cell secondary wall development of pear fruit mainly through reducing the expression levels of lignin monomer polymerisation key enzymes (PbPRX33 and PbPRX45). PbMADS49 was a transcriptional repressor inhibiting its transcription by binding to the CArG element in the target gene promoter. Combined with the co-expression network and promoter cis-acting element analysis, we hypothesised that PbMADS49 positively regulates the transcription of PbPRX33 through PbWRKY63. The gene silencing effect of homologous genes PbPRX33-1 and PbPRX33-2 was consistent with PbMADS49, and PbPRX33-2 was more significant than PbPRX33-1. This study shows that PbMADS49 is a positive regulator of stone cell lignification, providing new insights into the development mechanism of pear stone cells.

Wheat crop production is under constant threat from leaf and stripe rust, an airborne fungal disease caused by the pathogen Puccinia triticina. Early detection and efficient crop phenotyping are crucial for managing and controlling the spread of this disease in susceptible wheat varieties. Current detection methods are predominantly manual and labour-intensive. Traditional strategies such as cultivating resistant varieties, applying fungicides and practicing good agricultural techniques often fall short in effectively identifying and responding to wheat rust outbreaks. To address these challenges, we propose an innovative computer vision-based disease severity prediction pipeline. Our approach utilizes a deep learning-based classifier to differentiate between healthy and rust-infected wheat leaves. Upon identifying an infected leaf, we apply Grabcut-based segmentation to isolate the foreground mask. This mask is then processed in the CIELAB color space to distinguish leaf rust stripes and spores. The disease severity ratio is calculated to measure the extent of infection on each test leaf. This paper introduces a ground-breaking disease severity prediction method, offering a low-cost, accessible and automated solution for wheat rust disease screening in field conditions using digital colour images. Our approach represents a significant advancement in crop disease management, promising timely interventions and better control measures for wheat rust.

Outside Front Cover: The cover image is based on the article Genome-Wide Association Study Identifies the Serine/Threonine Kinase ClSIK1 for Low Nitrogen Tolerance in Watermelon Species by Mingfang Zhang et al., https://doi.org/10.1111/pce.15275.