The Population Characterization Of Phytophthora Infestans From 4 Provinces Of China In 2009 And The Molecular Marker Development Of A1, A2 Mating Type

Potato late blight caused by Phytophthora infestans is one of the most devastating diseases in potato production. A total of 181 isolates of P. infestans were collected from Hei Longjiang, JiLin, YunNan and Inner Mongolia provinces of China in 2009. 137 isolates were investigated for mating types and metalaxyl resistance and 118 isolates were assayed for physiological race. The genotypes of Self-fertility of P. infestans collected were also assessed for mitochondrial DNA haplotypes with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), simple sequence repeats (SSR) and amplified fragment length polymorphism (AFLP). At the same time, the molecular markers of the mating type of P. infestans were also studied. The results were as follows.1. One hundred and thirty seven isolates collected from Hei Longjiang, JiLin, YunNan and Inner Mongolia provinces of China in 2009 were investigated for mating types. The result showed that all the tested 32 isolates from YunNan were self-fertility. The remaining strains were all over the A1 mating type. The strains of A 2 mating type was not found.2. The results of the tested 137 isolates indicated that the ratio of resistant and sensitive isolates was 50% respectively in Hei Longjiang and the ratio of resistant and sensitive isolates was 70.8%, 29.8% respectively in JiLin. Intermediate isolates were not founded in the two provinces. The ratio of resistant, moderatly resistant and sensitive isolates was 53.1%, 3.1%, 43.8% respectively in YunNan and the ratio of resistant, moderatly resistant and sensitive isolates was 72.7%, 9.1%, 18.2% respectively in Inner Mongolia. However, all of the isolates from Dunhua were resistant and the isolates from Yushu were sensitive. The proportion of resistant and sensitive isolates was markedly different in different areas.3. Total of 42 races were identified from 118 collected isolates, all of them were complex-races possessing at least two virulence genes and contain an average of 8.73 virulence genes. In addition, there were 35 isolates called as"super virulence race", which can overcome all known 11 resistant genes (R1 to R11).4. The mitochondrial DNA haplotypes were assessed for the self-fertility strains and the genotype of all the strains tested were Ia. SSR genotypes were also determined with 6 pairs of SSR primers, the result indicated that the structure of self-fertility strains in Yunnan Province was lower in genetic diversity.5. A total of 16 descendants of different mating type were received, including 13 strains of A1 mating type, 2 strains of A2 mating type and 1 self-sterility strain by germination in aqueous solution.6. A total of 200 RAPD primers were screened for molecular markers linked to mating type and received two primers with high accuracy which can be used for detecting mating type of P. infestans.