Zhou Jinyan, Wang Min, Sun Yuming, Gu Zechen, Wang Ruirui, Saydin Asanjan, Shen Qirong, Guo Shiwei
Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing 210095, China.
Center of Agricultural Technology Extension, Kizilsu Kirghiz Autonomous Prefecture 845350, China.
Toxins (Basel). 2017 Mar 11;9(3):100. doi: 10.3390/toxins9030100.
Cucumber Fusarium wilt, induced by f. sp. (FOC), causes severe losses in cucumber yield and quality. Nitrogen (N), as the most important mineral nutrient for plants, plays a critical role in plant-pathogen interactions. Hydroponic assays were conducted to investigate the effects of different N forms (NH₄⁺ vs. NO₃) and supply levels (low, 1 mM; high, 5 mM) on cucumber Fusarium wilt. The NO₃-fed cucumber plants were more tolerant to Fusarium wilt compared with NH₄⁺-fed plants, and accompanied by lower leaf temperature after FOC infection. The disease index decreased as the NO₃ supply increased but increased with the NH₄⁺ level supplied. Although the FOC grew better under high NO₃ in vitro, FOC colonization and fusaric acid (FA) production decreased in cucumber plants under high NO₃ supply, associated with lower leaf membrane injury. There was a positive correlation between the FA content and the FOC number or relative membrane injury. After the exogenous application of FA, less FA accumulated in the leaves under NO₃ feeding, accompanied with a lower leaf membrane injury. In conclusion, higher NO₃ supply protected cucumber plants against Fusarium wilt by suppressing FOC colonization and FA production in plants, and increasing the plant tolerance to FA.
由尖孢镰刀菌黄瓜专化型（FOC）引起的黄瓜枯萎病会导致黄瓜产量和品质严重下降。氮（N）作为植物最重要的矿质营养元素，在植物与病原体的相互作用中起着关键作用。进行水培试验以研究不同氮形态（NH₄⁺与NO₃）和供应水平（低，1 mM；高，5 mM）对黄瓜枯萎病的影响。与供应NH₄⁺的黄瓜植株相比，供应NO₃的黄瓜植株对枯萎病的耐受性更强，且在感染FOC后叶片温度更低。病害指数随NO₃供应量的增加而降低，但随NH₄⁺供应水平的增加而升高。尽管FOC在体外高NO₃条件下生长更好，但在高NO₃供应的黄瓜植株中，FOC定殖和镰刀菌酸（FA）的产生减少，这与较低的叶片膜损伤有关。FA含量与FOC数量或相对膜损伤之间存在正相关。外源施用FA后，供应NO₃的叶片中积累的FA较少，同时叶片膜损伤较低。总之，较高的NO₃供应通过抑制FOC在植物中的定殖和FA的产生，以及提高植物对FA的耐受性，保护黄瓜植株免受枯萎病侵害。
