利用来自日本、国际水稻研究所(IRRI)和中国的10个稻瘟病菌单基因鉴别品种，将59个湖南稻瘟病菌株分别划分为20个生理小种，优势小种为H531.1、H511.1和H501.1，对抗性基因Pi–CO39、Pita、Pi3、Pi12、Pia具有致病性。各个稻区生理小种组成和优势小种存在差异，其中，湘东、湘中稻区稻瘟病菌生理小种多样性指数较高，优势小种的变化最为明显，说明这2个稻区的抗源基因正逐渐变得匮乏，甚至丧失。鉴别品种C101LAC(Pi1)和C101A51(Pi2)对59个湖南稻瘟病菌菌株抗性频率均为100.0%，说明这些抗性品种(基因)可作为湖南稻区稻瘟病的抗源材料(基因)，Pi1、Pi2可直接作为分子标记辅助选择育种的供体抗源基因。品种关东51(Pik)、C105TTP–4L23(Pi4–b)和 C101PKT (Pita)在湖南各稻区的抗性水平表现存在差异，可以作为选择性抗源材料(基因)加以应用。 Fifty-nine isolates of Magnaporthe oryzae that collected in Hunan province were divided into 20 races based on the reactions to 10 monogenic differential cultivars from Japanese, IRRI and Chinese differential cultivars. Dominant races in the fungal population were H531.1, H511.1 and H501.1, which were virulent to rice cultivar with blast resistance genes PiCO39, Pita, Pi3, Pi12 and Pia. The composition of races and dominant races of blast pathogen in different rice cropping regions of Hunan were different. High pathotypic diversities of physiological races of rice blast pathogen were observed and the dominant races were changed most frequently in rice cropping region of east and middle Hunan, indicating the resistance rice varieties (genes) against blast were becoming poor, even lost in such regions. Differential cultivars C101LAC (Pi1) and C101A51 (Pi2) expressed 100% resistance frequencies against 59 isolates, meaning the two varieties (genes) can be used as resistance gene source for Hunan rice cropping region, and the resistance genes Pi1, Pi2 can be used as donor genes for molecular marker-assisted selection breeding. Differential cultivars Kanto 51(Pik), C105TTP4L23 (Pi4b) and C101PKT (Pita), showed different resistance to blast fungal population, indicating that these resistance varieties (genes) can be used as selective resistance resources in different regions of Hunan. Key words: Oryza sativa; Magnaporthe oryzae; pathotypic diversity; differential cultivars; resistance genes; Hunan