A Simple and Accurate Resistance Identification Method of Rice to Neck Blast Disease InVitro

摘要

Twelve rice cultivars with differential resistance to rice blast disease (Magnaporthe oryzae (Hebert) Barr), including Tetep (R), IR36 (MR) and Lijiangxituanhegu (HS), and nine locally planted rice cultivars in Jiangxi helped establish an identification method for rice resistance to neck blast. We describe a new technique of dropping a spore suspension on the panicle segment invitro (DSSPS). This technique involved rice panicles that were initially 0.5-2cm in length and then cut into a 7- to 8-cm segment (i.e. an upper node of 1cm and a lower node of 6-7cm). The segment was placed into a Petri dish with a stack of sterile water saturated filter paper. The suspension (4l 1x10(5)spores/ml) was placed at each of three locations on the segment (with an approximate interval of 3cm). Disease severity was then assessed according to a 0-9 scale after incubating for 9days with a 12h/12h (light/day cycle) at 28 degrees C. Choosing a suitable developmental stage of the rice panicle and blast strains was a key to evaluate resistance accurately. DSSPS is a simple and accurate method of identifying rice resistance to neck blast as compared to injecting the spore suspension into the rice panicle invivo and resistance identification in natural nurseries. It is stressed that at least 20 single-spore strains are needed to accurately assess rice resistance to neck blast. We tested 1005 rice cultivars for neck blast resistance in Jiangxi province during 2010-2015, which showed an accuracy of 85.77% by DSSPS as compared with natural nursery data.