RESUMEN
The brown planthopper (BPH) Nilaparvata lugens is one of the most destructive insect pests on rice (Oryza sativa) in Asia. After landing on plants, BPH rapidly accesses plant phloem and sucks the phloem sap through unknown mechanisms. We discovered a salivary endo-ß-1,4-glucanase (NlEG1) that has endoglucanase activity with a maximal activity at pH 6 at 37°C and is secreted into rice plants by BPH NlEG1 is highly expressed in the salivary glands and midgut. Silencing NlEG1 decreases the capacity of BPH to reach the phloem and reduces its food intake, mass, survival, and fecundity on rice plants. By contrast, NlEG1 silencing had only a small effect on the survival rate of BPH raised on artificial diet. Moreover, NlEG1 secreted by BPH did not elicit the production of the defense-related signal molecules salicylic acid, jasmonic acid, and jasmonoyl-isoleucine in rice, although wounding plus the application of the recombination protein NlEG1 did slightly enhance the levels of jasmonic acid and jasmonoyl-isoleucine in plants compared with the corresponding controls. These data suggest that NlEG1 enables the BPH's stylet to reach the phloem by degrading celluloses in plant cell walls, thereby functioning as an effector that overcomes the plant cell wall defense in rice.
Asunto(s)
Endo-1,3(4)-beta-Glucanasa/metabolismo , Conducta Alimentaria/fisiología , Hemípteros/fisiología , Proteínas de Insectos/metabolismo , Oryza/parasitología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Pared Celular/metabolismo , Celulosa/metabolismo , Ciclopentanos/metabolismo , Endo-1,3(4)-beta-Glucanasa/clasificación , Endo-1,3(4)-beta-Glucanasa/genética , Fertilidad/genética , Regulación Enzimológica de la Expresión Génica , Hemípteros/enzimología , Hemípteros/genética , Interacciones Huésped-Parásitos , Proteínas de Insectos/clasificación , Proteínas de Insectos/genética , Oxilipinas/metabolismo , Floema/parasitología , Filogenia , Interferencia de ARN , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Saliva/enzimología , Homología de Secuencia de AminoácidoRESUMEN
Emerging evidence has shown the potential of oral microbiota as a noninvasive diagnostic tool in gastrointestinal (GI) cancer. PubMed, Web of Science, and Embase were systematically searched for eligible studies published until May 31, 2019. Of the 17 included studies published between 2011 and 2019, five kinds of GI cancer, including colorectal cancer (n=6), pancreatic cancer (n=5), gastric cancer (n=4), esophageal cancer (n=2) and liver cancer (n=1), were reported. Generally, the diagnostic performance of the multi-bacteria model for GI cancer was strong with the best area under the receiver operator characteristic curve (AUC) exceeding 0.90, but only one study had a validation phase. Pathogens involved in periodontal disease, such as Porphyromonas gingivalis and Tannerella forsythia, were linked to various kinds of GI cancer. Besides, more oral bacteria significantly differed between cases with upper digestive cancer and healthy controls when compared to colorectal cancer (the most common form of lower digestive cancer), probably indicating a different mechanism due to anatomical and physiological differences in the digestive tract. Oral microbiota changes were associated with risk of various kinds of GI cancer, which could be considered as a potential tool for early prediction and prevention of GI cancer, but validation based on a large population, reproducible protocols for oral microbiota research and oral-gut microbiota transmission patterns are required to be resolved in further studies.