Brown planthopper (BPH), Nilaparvata lugens Stål, is one of the most devastating insect pests of rice (Oryza sativa L.). Currently, 30 BPHresistance genes have been genetically defined, most of which are clustered on specific chromosome regions. Here, we describe molecular cloning and characterization of a BPH-resistance gene, BPH9, mapped on the long arm of rice chromosome 12 (12L). BPH9 encodes a rare type of nucleotide-binding and leucine-rich repeat (NLR)-containing protein that localizes to the endomembrane system and causes a cell death phenotype. BPH9 activates salicylic acidand jasmonic acid-signaling pathways in rice plants and confers both antixenosis and antibiosis to BPH. We further demonstrated that the eight BPH-resistance genes that are clustered on chromosome 12L, including the widely used BPH1, are allelic with each other. To honor the priority in the literature, we thus designated this locus as BPH1/9. These eight genes can be classified into four allelotypes, BPH1/9-1, -2, -7, and -9. These allelotypes confer varying levels of resistance to different biotypes of BPH. The coding region of BPH1/9 shows a high level of diversity in rice germplasm. Homologous fragments of the nucleotide-binding (NB) and leucine-rich repeat (LRR) domains exist, which might have served as a repository for generating allele diversity. Our findings reveal a rice plant strategy for modifying the genetic information to gain the upper hand in the struggle against insect herbivores. Further exploration of natural allelic variation and artificial shuffling within this gene may allow breeding to be tailored to control emerging biotypes of BPH.brown planthopper | plant-insect interaction | CNL protein | allelotype | evolution
The brown planthopper, Nilaparvata lugens, is a pest that threatens rice (Oryza sativa) production worldwide. While feeding on rice plants, planthoppers secrete saliva, which plays crucial roles in nutrient ingestion and modulating plant defense responses, although the specific functions of salivary proteins remain largely unknown. We identified an N. lugens-secreted mucin-like protein (NlMLP) by transcriptome and proteome analyses and characterized its function, both in brown planthopper and in plants. NlMLP is highly expressed in salivary glands and is secreted into rice during feeding. Inhibition of NlMLP expression in planthoppers disturbs the formation of salivary sheaths, thereby reducing their performance. In plants, NlMLP induces cell death, the expression of defense-related genes, and callose deposition. These defense responses are related to Ca 2+ mobilization and the MEK2 MAP kinase and jasmonic acid signaling pathways. The active region of NlMLP that elicits plant responses is located in its carboxyl terminus. Our work provides a detailed characterization of a salivary protein from a piercing-sucking insect other than aphids. Our finding that the protein functions in plant immune responses offers new insights into the mechanism underlying interactions between plants and herbivorous insects.
BROWN PLANTHOPPER RESISTANCE14 (BPH14), the first planthopper resistance gene isolated via map-based cloning in rice (Oryza sativa), encodes a coiled-coil, nucleotide binding site, leucine-rich repeat (CC-NB-LRR) protein. Several planthopper and aphid resistance genes encoding proteins with similar structures have recently been identified. Here, we analyzed the functions of the domains of BPH14 to identify molecular mechanisms underpinning BPH14-mediated planthopper resistance. The CC or NB domains alone or in combination (CC-NB [CN]) conferred a similar level of brown planthopper resistance to that of full-length (FL) BPH14. Both domains activated the salicylic acid signaling pathway and defense gene expression. In rice protoplasts and Nicotiana benthamiana leaves, these domains increased reactive oxygen species levels without triggering cell death. Additionally, the resistance domains and FL BPH14 protein formed homocomplexes that interacted with transcription factors WRKY46 and WRKY72. In rice protoplasts, the expression of FL BPH14 or its CC, NB, and CN domains increased the accumulation of WRKY46 and WRKY72 as well as WRKY46-and WRKY72-dependent transactivation activity. WRKY46 and WRKY72 bind to the promoters of the receptor-like cytoplasmic kinase gene RLCK281 and the callose synthase gene LOC_Os01g67364.1, whose transactivation activity is dependent on WRKY46 or WRKY72. These findings shed light on this important insect resistance mechanism.
The brown planthopper (BPH), Nilaparvata lugens (Stål), is a phloem sap-feeding insect. During the feeding on rice plant, BPH secretes salivary proteins with potential effector functions, which may play a critical role in the plant-insect interactions. However, a limited number of BPH effector proteins have been identified to date. Here, we sequenced the salivary gland transcriptomes of five BPH populations and subsequently established a N. lugens secretome consisting of 1140 protein-encoding genes. Secretome analysis revealed the presence of both conserved and rapidly evolving salivary proteins. A screen for potential effectors that elicit responses in the plant was performed via the transient expression analysis of 64 BPH salivary proteins in Nicotiana benthamiana leaves and rice protoplasts. The salivary proteins Nl12, Nl16, Nl28, and Nl43 induced cell death, whereas Nl40 induced chlorosis and Nl32 induced a dwarf phenotype in N. benthamiana, indicating effector properties of these proteins. Ectopic expression of the six salivary proteins in N. benthamiana up-regulated expression of defense-related genes and callose deposition. Tissue expression analysis showed a higher expression level of the six candidate effectors in salivary glands than in other tissues. Subcellular localization and analysis of domain required for cell death showed a diverse structure of the six effectors. Nl28, Nl40 and Nl43 are N. lugens-specific, in contrast, Nl12, Nl16, Nl32 are conserved among insects. Nl40 family has numerous isoforms produced by alternative splicing, exemplifying rapid evolution and expansion of effector proteins in the brown planthopper. Our results suggest a potential large effector repertoire in BPH and a higher level of effector conservation exist in BPH compared to that in plant pathogens.
Although Ru(II)-based agents are expected to be promising candidates for substituting Pt-drug, their in vivo biomedical applications are still limited by the short excitation/emission wavelengths and unsatisfactory therapeutic efficiency. Herein, we rationally design a Ru(II) metallacycle with excitation at 808 nm and emission over 1000 nm, namely Ru1085, which holds deep optical penetration (up to 6 mm) and enhanced chemo-phototherapy activity. In vitro studies indicate that Ru1085 exhibits prominent cell uptake and desirable anticancer capability against various cancer cell lines, especially for cisplatin-resistant A549 cells. Further studies reveal Ru1085 induces mitochondria-mediated apoptosis along with S and G2/M phase cell cycle arrest. Finally, Ru1085 shows precise NIR-II fluorescence imaging guided and long-term monitored chemo-phototherapy against A549 tumor with minimal side effects. We envision that the design of long-wavelength emissive metallacycle will offer emerging opportunities of metal-based agents for in vivo biomedical applications.
Histone lysine specific demethylase 1 (LSD1) has been recognized as an important modulator in post-translational process in epigenetics. Dysregulation of LSD1 has been implicated in the development of various cancers. Herein, we report the discovery of the hit compound 8a (IC 50 = 3.93 μmol/L) and further medicinal chemistry efforts, leading to the generation of compound 15u (IC 50 = 49 nmol/L, and K i = 16 nmol/L), which inhibited LSD1 reversibly and competitively with H3K4me2, and was selective to LSD1 over MAO-A/B. Docking studies were performed to rationalize the potency of compound 15u . Compound 15u also showed strong antiproliferative activity against four leukemia cell lines (OCL-AML3, K562, THP-1 and U937) as well as the lymphoma cell line Raji with the IC 50 values of 1.79, 1.30, 0.45, 1.22 and 1.40 μmol/L, respectively. In THP-1 cell line, 15u significantly inhibited colony formation and caused remarkable morphological changes. Compound 15u induced expression of CD86 and CD11b in THP-1 cells, confirming its cellular activity and ability of inducing differentiation. The findings further indicate that targeting LSD1 is a promising strategy for AML treatment, the triazole-fused pyrimidine derivatives are new scaffolds for the development of LSD1/KDM1A inhibitors.
BackgroundThermosensitive genic male sterile (TGMS) lines and photoperiod-sensitive genic male sterile (PGMS) lines have been successfully used in hybridization to improve rice yields. However, the molecular mechanisms underlying male sterility transitions in most PGMS/TGMS rice lines are unclear. In the recently developed TGMS-Co27 line, the male sterility is based on co-suppression of a UDP-glucose pyrophosphorylase gene (Ugp1), but further study is needed to fully elucidate the molecular mechanisms involved.ResultsMicroarray-based transcriptome profiling of TGMS-Co27 and wild-type Hejiang 19 (H1493) plants grown at high and low temperatures revealed that 15462 probe sets representing 8303 genes were differentially expressed in the two lines, under the two conditions, or both. Environmental factors strongly affected global gene expression. Some genes important for pollen development were strongly repressed in TGMS-Co27 at high temperature. More significantly, series-cluster analysis of differentially expressed genes (DEGs) between TGMS-Co27 plants grown under the two conditions showed that low temperature induced the expression of a gene cluster. This cluster was found to be essential for sterility transition. It includes many meiosis stage-related genes that are probably important for thermosensitive male sterility in TGMS-Co27, inter alia: Arg/Ser-rich domain (RS)-containing zinc finger proteins, polypyrimidine tract-binding proteins (PTBs), DEAD/DEAH box RNA helicases, ZOS (C2H2 zinc finger proteins of Oryza sativa), at least one polyadenylate-binding protein and some other RNA recognition motif (RRM) domain-containing proteins involved in post-transcriptional processes, eukaryotic initiation factor 5B (eIF5B), ribosomal proteins (L37, L1p/L10e, L27 and L24), aminoacyl-tRNA synthetases (ARSs), eukaryotic elongation factor Tu (eEF-Tu) and a peptide chain release factor protein involved in translation. The differential expression of 12 DEGs that are important for pollen development, low temperature responses or TGMS was validated by quantitative RT-PCR (qRT-PCR).ConclusionsTemperature strongly affects global gene expression and may be the common regulator of fertility in PGMS/TGMS rice lines. The identified expression changes reflect perturbations in the transcriptomic regulation of pollen development networks in TGMS-Co27. Findings from this and previous studies indicate that sets of genes involved in post-transcriptional and translation processes are involved in thermosensitive male sterility transitions in TGMS-Co27.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1114) contains supplementary material, which is available to authorized users.
Insect identification is the basis of insect research and disaster control and is of great importance for the design of pest control strategies and the protection of beneficial insects. Due to human subjective limitations and the small size and uneven distribution of pests, traditional methods of distinguishing and counting pest types based on experience cannot quickly and accurately detect and identify pests. Therefore, this paper proposes an object detection algorithm based on the improved Mask R-CNN model, aiming to improve the accuracy and efficiency in pest identification and counting. The algorithm improves the FPN structure in the feature extraction network and increases the weight coefficient when fusing feature layers of different scales. Based on the task of target detection and recognition, weight coefficient is adjusted to a proper parameter so that the semantic information and positioning information can be made full use to achieve more accurate recognition and positioning. The results of the experimental analysis of 1000 sample images show that the improved Mask R-CNN model has a recognition and detection accuracy of 99.4%, which is 2.7% higher than that of the unimproved Mask R-CNN model. The main contribution of this method is to improve the detection speed, and at the same time, the recognition accuracy has been significantly improved. This algorithm provides technical support for pest detection in the agricultural field and makes a contribution to the intellectualization of agricultural management.
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