摘要
Brown spot, caused by Bipolaris oryzae, is a very important disease of rice. This study investigated the effect of potassium (K) on rice resistance to brown spot. The working hypothesis tested was that higher foliar K concentration could allow plants to respond more efficiently against fungal infection. Plants were grown in nutrient solution amended with three K rates (0.5, 1.0 and 2.5 mM) and noninoculated or inoculated with B. oryzae. The photosynthetic performance of plants, activities of defence and antioxidant enzymes and the concentrations of reactive oxygen species, phenolics and lignin were determined. Foliar K concentration was significantly higher by 38% and 91% for plants supplied with 1.0 and 2.5 mM K, respectively, compared to plants supplied with 0.5 mM K. Brown spot severity was significantly higher (≥20%) for plants supplied with 1.0 and 2.5 mM K than those supplied with 0.5 mM K (≤15%). Higher brown spot severity for plants supplied with 2.5 mM K resulted in changes in the photosynthetic apparatus, reduced chlorophyll a + b and carotenoids concentrations, and higher production of hydrogen peroxide and superoxide anion radical. In contrast, higher activities of defence and antioxidant enzymes and more production of phenolics for plants supplied with 0.5 mM K helped them to cope with B. oryzae infection more efficiently. In conclusion, rice resistance against brown spot was achieved by keeping a lower foliar K concentration linked to more active defence reactions, a robust antioxidative system and less damage to the photosynthetic apparatus.
摘要译文
由双皮子or Zae引起的棕色斑点是大米非常重要的疾病。这项研究研究了钾（K）对棕色斑点的抗性的影响。测试的工作假设是，较高的叶面K浓度可以使植物对真菌感染的反应更有效。用三个K速率（0.5、1.0和2.5 mm）修改的营养溶液中生长植物，并无接种或与牛肉芽孢杆菌接种。确定了植物的光合作用，防御和抗氧化剂的活性以及活性氧，酚类和木质素的浓度。与供应0.5 mM K.的植物相比，叶面K浓度分别显着提高38％和91％，分别为1.0和2.5 mm k。2.5 mm K比提供0.5 mm K（≤15％）的K。提供2.5 mm k的植物的较高棕色斑点严重程度导致光合作用设备的变化，叶绿素A+B和类胡萝卜素浓度的降低以及过高的过氧化氢和超氧化物阴离子自由基的产生。相比之下，国防和抗氧化剂酶的较高活性以及提供0.5 mm K的植物的酚类产生更多，这有助于他们更有效地应对Oryzae感染。总之，通过保持较低的叶面K浓度与更活跃的防御反应，强大的抗氧化系统以及对光合作用设备的损害更少，可以实现对棕色斑点的抗性。
Leandro C. Silva[1];Andersom M. Einhardt[1];Verônica V. Brás[1];Lillian M. Oliveira[1];Joicy A. A. Chaves[1];Luiz F. C. C. Pinto[1];Fabrício A. Rodrigues[1]. Rice resistance against Bipolaris oryzae infection is mediated by lower foliar potassium concentration[J]. Plant Pathology, 2024,73(3): 548-563