Physiological and cytological mechanisms of silicon-induced resistance in rice against blast disease.
Rice (Oryza sativa L.) blast disease caused by Magnaporthe grisea is one of the most destructive diseases in the rice-growing areas of the world. Silicon is an important nutritional element especially for rice. Two near-isogenic lines of rice with different resistance to blast disease, i.e. CO39 (susceptible) and C101LAC (Pi-1) (resistant), were selected to determine the effects of Si amendment on the severity and incidence of rice blast disease. The physiological and cytological mechanisms involved in the induced disease resistance by silicon were investigated. Exogenous Si application at a concentration of 2 mM reduced the disease index by 45% for CO39 and 56% for C101LAC (Pi-1). Si application alone did not change lignin content and the activities of defense-related enzymes including peroxidase (POD), polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) in rice leaves of both isogenic lines. However, after inoculation with M. grisea, Si-treated rice plants significantly increased the activities of POD, PPO and PAL in leaves of both isogenic lines. Si and lignin content were also significantly increased in Si-treated inoculated seedlings. Environmental scanning electron microscope observations revealed that Si amendment resulted in higher Si deposit on dumbbell bodies in the rice leaves and silicon papilla accumulation on the guard cell of stoma. These results suggest that silicon-induced defense response and cell silicification of rice leaves altogether contribute to the silicon-induced rice resistance to blast disease.
Cai
Kunzheng
K
Institute of Tropical and Subtropical Ecology, South China Agricultural University, Guangzhou 510642, China. kzcai@scau.edu.cn
Gao
Dan
D
Luo
Shiming
S
Zeng
Rensen
R
Yang
Jianyuan
J
Zhu
Xiaoyuan
X
D004156:Catechol Oxidase / Q000378:metabolism; D054884:Host-Pathogen Interactions; D007113:Immunity, Innate / Q000187:drug effects; D008031:Lignin / Q000378:metabolism; D020082:Magnaporthe / Q000502:physiology*; D008855:Microscopy, Electron, Scanning; D012275:Oryza / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology*; D009195:Peroxidase / Q000378:metabolism; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D018515:Plant Leaves / Q000378:metabolism / Q000382:microbiology / Q000648:ultrastructure; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D012825:Silicon / Q000494:pharmacology*
D008031:Lignin; D004156:Catechol Oxidase; D009195:Peroxidase; D010650:Phenylalanine Ammonia-Lyase; D012825:Silicon