线虫Nematology
Plant-parasitic nematodes cause substantial economic losses to global agriculture yearly. The use of nematicides is an effective way of controlling plant-parasitic nematodes. However, the long-term use of traditional organophosphorus and carbamate chemical nematicides can lead to increased nematode resistance. With the increasing awareness of the necessity for the protection of the environment and human health, highly toxic nematicides no longer meet the developmental requirements of modern agriculture. Recently, many studies have been undertaken on the isolation and nematicidal activity of natural products against plant-parasitic nematodes and Caenorhabditis elegans. As an important model nematode, C. elegans plays a vital reference role in studying plant-parasitic nematodes regarding nematicidal activity, metabolic mechanism, and modes of action and target. We reviewed the latest research progress of natural nematicidal active compounds against plant-parasitic nematodes and C. elegans over the past ten years, discussed the structure-activity relationship and mechanism of action, and examined the development and application of natural nematicidal active compounds.
were inoculated with 2 000 eggs, and cultured in an incubator at 23°C/20°C with a 16 h/8 h light/dark photoperiod. After three months inoculation, 36±7.2 cysts and females were extracted from the infested potato roots, no females and cysts were observed on control plants.
This is the first report of potato golden cyst nematode G. rostochiensis in China.
Radopholus similis (Cobb 1893) Thorne (1949) is a destructive migratory endoparasitic plant nematode. In this study, the pathogenic process of R. similis infection in Nicotiana benthamiana (tobacco) was studied using quartz sand culture in laboratory. The results showed that R. similis mainly parasitised the root cortex, leading to cortical cell decomposition and tissue decay. We optimised the inoculation conditions to establish a method for determining the pathogenicity of R. similis as follows: (1) a glass culture tube was filled with quartz sand (about 1/3 of the height) and sterilised twice; (2) 20-day-old N. benthamiana seedlings were transplanted into test tubes and cultivated for 10 days at (25±1)°C; (3) R. similis female nematodes were inoculated in the root rhizosphere at a rate of 150 nematodes per plant; (4) the number of nematodes, disease severity, and growth of the plant at 30 days post-inoculation (dpi) were determined. The pathogenicity of eight R. similis populations from different hosts was determined, which proved the feasibility of this method.
Soybean cyst nematode (SCN) Heterodera glycines is considered as the major constraint to soybean production. GmSHMT08 at Rhg4 locus on chromosome 08, encoding a serine hydroxylmethyltransferase, is a major gene underlying resistance against H. glycines in Peking-type soybeans. However, the molecular mechanism underpinning this resistance is less well characterized, and whether GmSHMT08 could interact with proteins in H. glycines remains unclear. In this study, yeast two-hybrid screening was conducted using GmSHMT08 as a bait protein, and a fragment of a 70-kDa heat shock protein (HgHSP70) was screened from H. glycines that exhibited interaction with GmSHMT08. This interaction was verified by both GST pull-down and bimolecular fluorescence complementation assays. Our finding reveals HgHSP70 could be applied as a potential candidate gene for further exploring the mechanism on GmSHMT08-mediated resistance against SCN H. glycines.
Potassium (K), an important nutrient element, can improve the stress resistance/tolerance of crops. The application of K in resisting plant-parasitic nematodes shows that the K treatment can reduce the occurrence of nematode diseases and increase crop yield. However, data on K2SO4 induced rice resistance against the root-knot nematode Meloidogyne graminicola are still lacking. In this work, K2SO4 treatment reduced galls and nematodes in rice plants and delayed the development of nematodes. Rather than affecting the attractiveness of roots to nematodes and the morphological phenotype of giant cells at feeding sites, such an effect is achieved by rapidly priming hydrogen peroxide (H2O2) accumulation and increasing callose deposition. Meanwhile, galls and nematodes in rice roots were more in the potassium channel OsAKT1 and transporter OsHAK5 gene-deficient plants than in wild-type, while the K2SO4-induced resistance showed weaker in the defective plants. In addition, during the process of nematode infection, the expression of jasmonic acid (JA)/ethylene (ET)/brassinolide (BR) signaling pathway-related genes and pathogenesis-related (PR) genes OsPR1a/OsPR1b was up-regulated in rice after K2SO4 treatment. In conclusion, K2SO4 induced rice resistance against M. graminicola. The mechanism of inducing resistance was to prime the basal defense and required the participation of the K+ channel and transporter in rice. These laid a foundation for further study on the mechanism of rice defense against nematodes and the rational use of potassium fertilizer on improving rice resistance against nematodes in the field.