| Potato is one of the most important crops in northwestern China. However, Potato production has been hampered by late blight disease that caused by the oomycete pathogen Phytophthora infestans. A thorough knowledge of the P. infestans population structure and dynamics is important for application of late blight management strategies and disease-resistant cultivars. Due to the complex and ever-changing pathogen structure, it is necessary to evaluate the resistance of domestic potato cultivars and newly-developed potato lines to diminish the late blight epidemics by emerging P. infestans lineages. Meanwhile, monitoring pathotype diversity in pathogen populations and resistance genes in domestic potato cultivars can assist in R gene deployment and the resistance breeding.A number of P.infestans isolates were collected from the germplasm nursery for resistance evaluation. Pathotype was determined on a set of potato differential lines, which possesses one of the R1-R11 race-specific resistance genes from Solanum demissum. In addition, the resistance of domestic potato cultivars and lines were tested both in the field and in laboratory. Last, the composition of resistance genes of potato cultivars was detected according to recognition of Avr-R gene pair. The main results are as follows:1. The pathotype of fifty-five isolates were tested by inoculation on differential potato lines. A total of nine pathotypes were identified:1.2.3.4.5.6.7.8.9.10.11,1.2.3.4.5.6.8.9.10.11, 1.2.3.4.6.8.10.11,2.3.4.5.6.7.8.10.11,2.3.4.6.8.9.10.11,3.4.6.8,3.4.6.8.10,3.4.6.8.10.11 and 3.4.6.8.9.10.11, of which 3.4.6.8.10.11,3.4.6.8.9.10.11 and 1.2.3.4.5.6.7.8.9.10.11 are the dominant pathotype at a frequency of 29.1%,23.6% and 21.8%, respectively. And 12 isolates can infect potato cultivars with any of 11 resistance genes.2. The resistance of total of 30 potato cultivars was tested by natural infection in open field and indoor detached leaflets inoculation,This result is the same as the appraisal result in field natural and indoors inoculation. The majority of cultivars showed differential susceptibility. only longshu 6, D520, L0527-7 and zhuangshu 3 showed excellent resistance in two condition.3. Transient expression 10 avirulent genes of late blight pathogen were employed to identify the resistance gene in 17 potato cultivars. The results showed that 10 genes were distributed in 17 cultivars, but the composition of resistance genes in each species is different. Resistant genes Rpi-Smira1,R4,R3 b and Rpi-vnt1 were widely distributed in tested potato cultivars, R1、R2 and R3 a were less distribution.In addition, the field resistance of cultivars is co-related with the number of identified resistant gene. High resistant variety containing more resistant genes, the susceptible cultivars containing less resistant genes. |
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