pHBA对菜心炭疽病的诱导抗性及植株生理特性的影响

Effects of p-hydroxybenzoic acid on induced resistance of flowering Chinese cabbage to anthracnose and the associated plant physiological characters

以菜心品种为材料,设置不同浓度对羟基苯甲酸(pHBA)处理,并通过人工接种炭疽病菌,研究pHBA对菜心炭疽病的诱导抗性作用机理。结果表明,在菜心生长发育过程中根系可以分泌出pHBA。pHBA对菜心的生长、产量形成和炭疽病的发生有明显的影响。适宜浓度的pHBA处理可促进菜心生长,提高植株对炭疽病的抗性,显著地降低病情指数(DI),提高菜薹产量,但当pHBA积累到一定浓度时,就对菜心植株产生自毒作用,提高DI和降低菜薹产量。炭疽病菌的感染破坏了植株细胞膜,增强细胞膜透性水平,诱导产生病程相关蛋白(几丁质酶、β-1,3-葡聚糖酶)和细胞壁物质(木质素、富含羟脯氨酸糖蛋白(HRGP))。适宜浓度的pHBA处理可抑制炭疽病菌对细胞膜透性的伤害,加强诱导提高几丁质酶活性、β-1,3-葡聚糖酶活性、木质素含量和HRGP含量,引起细胞壁木质化加强,增加了菜心植株对炭疽病的诱导抗病能力,从而阻止病原菌进一步侵入和扩散,抑制炭疽病菌对菜心产量造成的损失。

In this study, the mechanism of p-hydroxybenzoic acid （pHBA） on induced resistance of flowering Chinese cabbage to anthracnose （ Colletotrichum higginsianum Sac. ） was investigated by inoculation of plants with C. higginsianum, along with pHBA treatment. The results showed that root system of flowering Chinese cabbage could secrete pHBA during the growth period. Exogenous pHBA exerted obvious effects on plant growth, yield formation and disease incidence of anthracnose. Appropriate concentration of pHBA could promote plant growth, enhance their resistance against anthracnose, and therefore significantly reduce disease index （DI） and improve the yield. However, autointoxication occurred in plants when the concentration of pHBA was higher, accompanied by the increased DI and reduced yield. C. higginsianum infection destroyed cell membrane, increased membrane permeability, and induced formation of pathogenesis-related proteins （PRs）, such as chitinases and β-1,3-glucanases, and cell wall substances such as lignin and hydroxyprolinerich glycoproteins （HRGP）. Appropriate concentration of pHBA was able to inhibit the deleterious effects of anthracnose on cell membrane permeability, induce high levels of chitinase and β-1,3-glucanase, and increase lignin and HRGP content. As a result, appropriate pHBA treatment strengthened the cell wall ligniflcations, increased the induced resistance of plants toward anthracnose, and prevented further invasion, spreading of the pathogen and related yield loss in flowering Chinese cabbage.