| Rice blast disease, caused by Pyricularia grisea Sacc., is one of the most destructive diseases worldwide. Breeding resistant cultivars is the most effective and economical way to control this disease, but the resistance is often lost in a few years after the cultivars were released due to high variability of rice blast fungus. Therefore, information about the virulence of blast fungus and identification of novel blast resistance genes are needed in rice breeding programs.With LTH as recurrent parent, 6 NILs and 24 monogenic lines of rice for blast resistance had been developed. Their monogenic resistance to Chinese isolates were tested with 322 isolates collected from all over the country. The results showed that the resistance gene in IRBL15 might not be the Pi-t in K59 and the resistance gene in F98-7 might not be the Pi-K in Tsuyuake. IRBL1 and IRBL2, IRBL4 and IRBL5, IRBL12 and IRBL13, F124-1 and IRBL12, F124-1 and IRBL13, IRBL16 and IRBL17, IRBL6 and F80-1, IRBL7 and F129-1, IRBL14 and F145-2 have different resistance genes. Tested with susceptible F3 lines, IRBL1, IRBL3, IRBL8, IRBL10, IRBL11, IRBL19, IRBL20 IRBL21 have more than one resistance gene.Twelve monogenic lines were selected to construct a new set of differentials suitable for all the rice growing regions in China and 322 monospore isolates were classified into 182 pathogenic races and 135 of them had be detected only once. Sixty-six races that have high virulence, had been detected 50 times in Northern region and 54 times in Southern region. Eighty-seven races that have moderate virulence, had been detected 77 times in Northern region and 76 times in Southern region. Twenty-nine races that have low virulence, had been detected 35 times in Northern region and 30 times in Southern region. The differentiating ability of new differential system have no significant difference with Kiyosawa's differential varieties in Jilin, Liaoning, Jiangsu, Zhejiang, Sichuan and Guangdong, but it have higher differentiating ability than Kiyosawa's differential varieties in Hebei,Yunnan, Hunan and Fujian. New differential system have higher differentiating ability than Chinese differential varieties in Liaoning,Jiangsu, Hebei,Yunnan and Fujian, but they have the samedifferentiating ability in Jilin, Zhejiang ,Sichuan, Hunan and Guangdong provinces.Three hundred and twenty-two rice blast monospore isolates were collected from Jilin, Liaoning, Hebei, Jiangsu, Zhejiang, Sichuan, Hunan, Fujian, Guangdong and Yunnan provinces in China. The diversity and geographic distribution of virulence genes of these isolates were tested with 28 monogenic lines. The results showed that the occurrence frequency of Av-kh+,Av-z+,Av-z5+ and Av-9(t)+ were lower than 20%. and that of Av-a(1)+,Av-A(2)+, Av-i+, Av-7(t)+, Av-3+, Av-b+, Av-KP+, Av-ks(1)+, Av-ks(2)+,Av-ta(1)+, Av-ta(2)+, Av-sh(1)+, Av-sh(2)+ and Av-19(t)+ were all higher than 50%. The frequency of virulence genes in Northern region and Southern region had no correlation with the type of donors of the corresponding resistance genes.Pi-9(t) could be used in all the rice growing regions in China. Pi-z' could be used in Yunnan,Jilin,Jiangsu and Zhejiang provinces. Pi-z5 could be used in Northern region , Guangdong,Fujian,Sichuan,Jiangsu and Zhejiang provinces in Southern region. Pi-z could be used in Fujian,Yunnan,Sichuan,Liaoning,Zhejiang,Hebei and Jiangsu. Pi-kh could be used in Yunnan,Guangdong,Sichuan,Fujian and Jiangsu. Pi-l,Pi-k,Pi-k(c), Pi-ta2,Pi-5(t),Pi-12(t),Pi-b(c),Pi-kp,Pi-kp(c) and Pi-ta(c) have lost their resistance in most of the rice growing regions, but they could be used with other resistance genes in breeding programs. Pi-a(l), Pi-a(2), Pi-i, Pi-7(t), Pi-3, Pi-b, Pi-ks(1), Pi-ks(2), Pi-ta(1), Pi-ta(2), Pi-sh(1),Pi-sh(2) and Pi-19(t) could not be utilized in any rice growing regions in China.Xinguangmei, Sanhuangzhan and 96-229 have Pi-zt or the alleles of Pi-zt. Shanlouping,Yangmaogu and Baiergu have one resistance gene that different from Pi-zt. Tonghongl,84H110/242,84H110/1242,Tunshanz...
|
PDF Full Text Request