A study on the pathogen species and physiological races of tomato Fusarium wilt in Shanxi,China

In order to clarify the main pathogens of tomato Fusarium wilt in Shanxi Province, China, morphological identification, elongation factor 1 alpha （EF-1α） sequence analysis, specific primer amplification and pathogenicity tests were applied to study the isolates which were recovered from diseased plants collected from 17 different districts of Shanxi Province. The results were as follows： 1） Through morphological and molecular identification, the following 7 species of Fusarium were identified： F. oxysporum, F. solani, F. verticillioides, F. subglutinans, F. chlamydosporum, F. sporotrichioides, and F. semitectum; 2） 56 isolates of F. oxysporum were identified using specific primer amplification, among which, 29, 5 and 6 isolates were respectively identified as F. oxysporum f. sp. lycopersici physiological race 1, race 2, and race 3; 3） pathogenicity test indicated the significant pathogenicity of F. oxysporum, F. solani, F. verticillioides, and F. subglutinans to tomato plant. Therefore, among these 4 species confirmed as pathogenic to tomato in Shanxi, the highest isolation rate （53.3％） corresponded to F. oxysporum. Three physiological species, race 1, race 2, and race 3 of F. oxysporum f. sp. lycopersici are detected in Shanxi, among which race 1 is the most widespread pathogen and is also considered as the predominant race.

Identification and Analysis of Physiological Races of Magnaporthe oryzae in Heilongjiang Province

A totatl of 116 isolates of rice blast fungus, Magnaporthe oryzae, were collected from 45 samples in different counties of Heilongjiang Province, and 20 Chinese physiological races belonging to seven groups were identified by using seven standard Chinese rice blast identifying varieties. Results showed that the dominant groups could be ranked as ZA, ZD, and ZB, with the occurrence frequencies of 47.41%, 22.41% and 15.52%, respectively. The race ZA49 was the dominant race with the occurrence frequency of 26.72%. The occurrence frequencies of the races ZD5 and ZD1 were 10.34% and 8.62%, respectively. The rising occurrence frequencies of these three dominant species were the most important reasons that causing Kongyu-131 more sensitive to rice blast. The results of virulence frequency indicated that the race harboring Pi-k, Pi-i, Pi-a gene were more susceptible to rice blast in Heilongjiang Province, and they should not be large-scale cultivated.

Identification of Physiological Races of Pyricularia oryae in Heilongjiang Province of China from 2007 to 2011

In order to clear the composition and distribution of physiological races of Pyricularia oryae in Heilongjiang Province, 299 single spore isolates of P. oryae collected from five rice regions （30 cities, counties or farms） in Heilongiiang Province form 2007 to 2011 were identified by seven differential varieties in Chi- na, and a total of seven groups with 31 physiological races had been identified. The results showed that ZA, ZD and ZB groups were the dominant groups in Hei- longjiang Province, with the occurrence frequencies of 34.8%, 31.1% and 16.1%, respectively. ZD5 was the dominant race with the oeeurrence frequency of 17.1% ; followed by ZA49 and ZD1 , with the occurrence frequencies of 13.7% and 10.7% , respectively. The types and compositions of physiological races of P. oryae varied with rice regions.

Preliminary Study on Physiological Race Differentiation in Tomato Leaf Mold in Three Northeastern Provinces of China

Tomato leaf mold samples collected from tomato plants cultivated in plastic house in three northeastern provinces of China were studied by artifical spray inoculation at seedling stage,consulting Hubbcling physiological race differential hosts and adopting Day's classification system(1971).The results indicated that there were three races in these provinces;they were races 1,2,3,race 1,3 and race 3.Among them race 1,2,3 was the predominant.

Genetic Analysis of Stripe Rust Resistance of Xikemai 6 at Adult Plant Stage

To confirm resistance and genetic rules of Xikemai 6 against physiological races of wheat stripe rust,physiological races CYR31,CYR32 and CYR33,Su11-4 and V26 were inoculated in Xikemai 6 and Mingxian 169 and their hybrid progenies F_1,F_2 and F_3 at adult plant stage on March 2015. The results showed that the resistance of Xikemai 6 against CYR31 was controlled by 2 pairs of dominant genes and a pair of recessive genes; the resistance against CYR32 was controlled by three pairs of dominant resistant genes（ two pairs of genes performed cumulative effect）; the resistance against CYR33 was controlled by a pair of dominant genes and a pair of recessive genes; the resistance against Su11-4 was controlled by a pair of dominant genes and a pair of recessive genes independently or collaboratively; the resistance against V26 was controlled by a pair of dominant genes independently. Due to good performance of Xikemai 6 in test and production,as well as years of resistance identification and genetic analysis,Xikemai 6 was proved to be an excellent cultivar with good resistance against stripe rust,and the inheritance of its resistance was stable,so Xikemai 6 could be used as a germplasm resource and resistance material with excellent comprehensive character. Molecular marker and localization could be further studied,to provide new resistance parents for disease-resistant breeding of wheat.

Race Structure and Distribution of Phytophthora infestans in the Investigated Areas of China

Ninety isolates collected from five different provinces and cities (Hebei, Yunan, Sichuan, Chongqing, Inner Mongolia ) during 1997 - 1998 were tested with potato clones possessed 8 dominant mono-genes R1, R3, R4, R6, R7, R9, R10, R11 and the combination of R1-R4 of the international late blight differential host. It concluded that: (1) in the 90 isolates tested 21 different races were detected, of which the 1.3.4. 7. 9. 10. 11 was very common with frequency of 32. 2%, followed by 1. 3. 4. 6. 7. 9. 10. 11 and 3.4.7. 9. 11 with frequency of 10.0%; (2) all tested resistant genes were compatible to the virulent gene of isolates of Phytophthora infestans assayed, which indicated that the virulent genes were very common in the tested population of Phytophthora infestans.