离体水稻叶片划伤接种鉴定稻瘟菌的致病型

抗瘟品种的培育和抗瘟基因布局需要快速、准确、大规模地定性水稻抗源及其后代的抗瘟基因型和稻瘟菌致病型。为此, 本研究建立了水稻离体叶片划伤接种方法。该方法依据主效抗瘟基因抵抗稻瘟菌在寄主体内扩展的特点, 通过针刺在水稻叶片上造成伤口, 避免了寄主侵入抗性的干扰, 从而有利于抗扩展性的定性鉴定。作者利用活体喷雾接种、叶片无划伤接种和本研究建立的离体叶片划伤接种等3种接种方法, 在秧苗4~6叶龄期, 对菌株12-DG-68在24个水稻抗瘟单基因系上的致病反应进行了测定, 结果显示：叶片划伤接种的检测结果稳定、一致; 而叶片无划伤接种和活体喷雾接种的检测结果假抗性比例分别为12.5%和4.2%, 不同叶龄期的叶片间反应型不一致率达7%。此外, 离体叶片划伤接种还可利用菌丝块接种, 以鉴定分生孢子产量低的菌株的致病型。因此, 水稻叶片划伤接种是一种准确、稳定和方便的稻瘟菌接种方法, 可用于大规模定性测定水稻抗源及其后代的抗瘟基因型和稻瘟菌的致病型。

Identification of Magnaporthe oryzae pathotypes by wounding inoculation of detached rice leaves

For rice blast resistance breeding and blast resistance gene deployment, it is required to establish an accurate, rapid and large scale inoculation method of Magnaporthe oryzae. Here, we report a wounding inoculation method of detached rice leaves. A key step of the method was to make wounds on rice leaves to avoid interference of host plant penetration resistance, which made use of the characteristics of major blast resistance genes that function against development and expansion of the fungal infection hyphae within host tissue. With the method developed in the present study, the leaf spot inoculation method and the spraying inoculation method, we assayed the reactions of 24 rice monogenic lines to a field isolate of M. oryzae, 12-DG-68, and compared reaction differences between the three methods. The results showed that the wounding inoculation generated consistently identical reactions to the isolate on rice leaves from any of the fourth, the fifth and the sixth stage seedlings. In contrast, there were 12.5% and 4.2% false resistant reactions generated by the leaf spot inoculation method and the spraying inoculation method, respectively. With the two traditional inoculation methods, there were also approximately 7% reactions that were inconsistent between leaves from different stages of rice seedlings. In addition, our wounding inoculation method could use mycelium blocks as inocula, which is useful for identifying the pathotypes of M. oryzae isolates that produce a small number of conidia. In summary, our results demonstrated that the wounding detached rice leaf inoculation is an accurate, stable and convenient method for large scale assay of the pathotypes of M. oryzae isolates.