Identification Of Pathogens Causing Kenaf Anthracnose,Cloning And Analysis Of NBS-LRR Like Analogs Resistance Gene In Kenaf

Kenaf(Hibiscus cannabinus L.)is one of the most economically important crops in spinning industry. Kenaf anthracnose is one of the most servere diseases for kenaf.It seriously impacts on the yield and quality of kenaf, causing huge economic losses. Four typical strains were isolated from diseased kenaf samples of Anhui, Henan, Zhejiang, Fujian provinces and their pathogenicities were determined. Strain identification was carried out by using traditional morphological methods and sequencing of rDNA-ITS. Strain with relatively strong pathogenicity was inoculated on kenaf germplasm resources and in order to screen out kenaf varieties of highly resistance Colletotrichum. Degenerate primers were designed basing on the NBS conserved motif. Diseases resistance genes were homologous cloned from the genome of highly resistance kenaf anthracnose. The results obtained in this study were as the follows:(1) The samples of diseased kenaf were collected and isolated from Anhui, Henan, Zhejiang, Fujian provinces of China. AH, HN, ZJ, FJ strains were selected from Sixteen pathogens and their pathogenicities were determined. Identification was carried out by using traditional morphological methods and sequencing of rDNA-ITS. The differences between AH, HN, ZJ strains and FJ strain in morphological characteristics and pathogenicities were relatively abundant. The rDNA-ITS sequence lengths of AH, HN, ZJ, FJ strains were 541,545,541,535 bp relatively. The homology between FJ strain and other strains was 90%-91%,and the homology between AH、HN、ZJ strains was 96%-98%. Colletotrichum.dematium was found as possible pathogen of kenaf anthracnose in Anhui, Henan, Zhejiang provinces,and C. gioeosporioides was found as possible pathogen of kenaf anthracnose in Fujian provinces. The pathogenicity of C. dematium was greater than C. gioeosporioides.(2) ZJ strain was the strongest pathogenic species and produced the most spores. The strain was inoculated on 160 kenaf varieties with or without wound respectively in the field. The result showed the degree of disease had large differences between different cultivars, and seven kenaf varieties showed high disease resistance. The same treatments on 17 kenaf varieties were performed in the greenhouse. All the tested varieties could be penetrated by Colletotrichum indicum.Fuhong 992、Fuhong 991 and Xinan Wuci et al were high resistant kenaf varieties.(3) Degenerate primers were designed basing on the NBS conserved motif. Five resistance gene analogues (RGAs) of NBS were isolated from the genome of Fuhong 992 by polymerase chain reaction (PCR). Sequence analysis showed that all RGAs contained four conserved motifs of NBS,which included P-loop, kinase-2a domain, kinase-3a domain and HD. It showed five RGAs may be connected with disease resistance. And the analysis study also found five RGAs of kenaf were divided into two classes, TIR-NBS-LRR type and nonTIR-NBS-LRR type. The result confirmed the early reported that ANBS-LRR gene had two major groups in dicotyledonous species.