College of Food Science and Engineering, Dalian Ocean University, Dalian 116023, China; Dalian Engineering Research Center for Carbohydrate Agricultural Preparations, Dalian Technology Innovation Center for Green Agriculture, Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Dalian Engineering Research Center for Carbohydrate Agricultural Preparations, Dalian Technology Innovation Center for Green Agriculture, Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Int J Biol Macromol. 2023 Jul 31;244:125281. doi: 10.1016/j.ijbiomac.2023.125281. Epub 2023 Jun 16.
Sheath blight, caused by Rhizoctonia solani (R. solani), is one of the most serious diseases of rice. Extracellular polysaccharides (EPS) are complex polysaccharides secreted by microbes that have a pivotal role in the plant-microbe interaction. At present, many studies have been carried out on R. solani, but it is not very clear whether the EPS is secreted by R. solani exists. Therefore, we isolated and extracted the EPS from R. solani, two kinds of EPS (EW-I and ES-I) were obtained by DEAE-cellulose 52 and Sephacryl S-300HR column further purification, and their structures were characterized by FT-IR, GC-MS, and NMR analysis. The results showed that EW-I and ES-I had similar monosaccharide composition but different molar ratio, they were composed of fucose, arabinose, galactose, glucose, and mannose with a ratio of 7.49: 27.72: 2.98: 6.66: 55.15 and 3.81: 12.98: 6.15: 10.83: 66.23, and their backbone may be composed of →2)-α-Manp-(1→ residues, beside ES-I was highly branched compared to EW-I. The exogenous application of EW-I and ES-I had no effect on the growth of R. solani AG1 IA itself, but their pretreatment of rice induced plant defense through activation of the salicylic acid pathway, resulting in enhanced resistance to sheath blight.
茎基腐病由立枯丝核菌（Rhizoctonia solani，R. solani）引起，是水稻最严重的病害之一。胞外多糖（EPS）是微生物分泌的复杂多糖，在植物与微生物互作中起着关键作用。目前，对立枯丝核菌的研究很多，但 R. solani 是否分泌 EPS 尚不清楚。因此，我们从立枯丝核菌中分离并提取了 EPS，通过 DEAE-纤维素 52 和 Sephacryl S-300HR 柱进一步纯化，得到两种 EPS（EW-I 和 ES-I），并用 FT-IR、GC-MS 和 NMR 分析对其结构进行了表征。结果表明，EW-I 和 ES-I 的单糖组成相似，但摩尔比不同，它们由岩藻糖、阿拉伯糖、半乳糖、葡萄糖和甘露糖组成，摩尔比为 7.49:27.72:2.98:6.66:55.15 和 3.81:12.98:6.15:10.83:66.23，其主链可能由→2)-α-Manp-(1→残基组成，与 EW-I 相比，ES-I 的支化程度更高。EW-I 和 ES-I 的外源添加对 R. solani AG1 IA 本身的生长没有影响，但它们预先处理水稻可通过激活水杨酸途径诱导植物防御，从而增强对茎基腐病的抗性。
