Studies On Identification Of Ramie Anthracnose And Biochemical Mechanism Of Ramie Resistance

Anthracnose (Colletotrichum boehmeriae Swwada) is regarded as one of the most widespread and devastating diseases of ramie. Seriously infected seedlings always lodge and even die due to the disease in large area, and adult plants have perforations on infected leaves, yellow and caducous leaves, red fibers which are difficult to bleach and decrease the fiber fineness, fiber strength and filament elongation ratio, which in all negatively affect the production and quality of ramie fiber. There was no systemic report of ramie anthrax although relative documents have existed in China. This study revealed the ITS pathogen identification of 19 kinds of anthrax strains separated from pathogen which were obtained from Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changshang, China and also focused on the protective enzyme activity and changes in contents of malonaldehyde and soluble protein of the infected ramie which were resistant and infectious to anthrax. This research also presented an analysis of the relationship between activities of some important defense enzymes in ramie and Colletotrichum boehmeriae -resistance of ramie and discussed biochemical mechanism of ramie's resistance to diseases, which would provide significant instructions of the resistance gene cloning and breeding resistant varieties theoretically and practically.In this study, 19 strains of Colletrichum sp. were isolated from ramie infectious with Anthracnose collected from Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changshang. The results of extending sequencing and analyzing rDNA-ITS of all the tested strains, together with the sequence information cluster analysis compared with the database sequences showed that: the PCR amplified ITS region (ITS3-ITS4) was about 575 bp in length in all the tested strains. There was no significant difference among lengths of sequence of ITS sections and content of GC; all tested strains were homology to the extent of 100% and could be divided into 2 groups , Type I was consisted of 9 isolated, namely 1; 2; 10; 4; 17; 14; 11; 8; 16, and Type II includes 15; 7; 13; 19; 9; 12; 18; 3; 5. Results of blast comparison in NCBI indicated that the two groups were Colletotrichum gloeosporioides.The dynamic changes in the activities of some important defense enzymes and the content of malonaldehyde (MDA) and soluble protein in ramie were analysised using "Huazhu No.4" and "Xiangzhu No.1". The results showed that:1. the activity of the defensive enzymes and the content of malondialdehyde, soluble protein did not change significantly when anti-/ flu varieties were sprayed with water, but the activity of POD, SOD in the disease-resistant varieties of the huazhu No.4 was significantly higher than the susceptible XiangZhu No. 1, and the activity PPO, the content of MDA and soluble protein was basically the same.2. the POD activities rising rapidly, the first maximums of Huazhu No.4 appeared earlier after inoculation; the second maximums of Huazhu No.4 appeared in 72 h after injection , the POD activity of Huazhu No.4 fall slowly than xiangzhu 1, and kept higher activities in later period. This indicated that POD activity and ramie disease resistance were positively correlated.3. the SOD activities of two varieties appeared exactly the opposite trend, the SOD activities of Huazhu No.4 appeared down-trend at first and up-trend later, and kept higher activities in later period; the SOD activities of XiangZhu No.1 appeared up-trend first and down-trend later, which showed that SOD activity in the early changes and ramie blast resistance were negatively correlated;4. the MDA content of two varieties appeared up-trend at first and down-trend later, the maximums of Huazhu No.4 appeared earlier (36h) than XiangZhu No.1 after inoculation .the rising rates of Huazhu No.4 were also higher. But the falling rates of Huazhu No.4 were faster than Xiangzhu 1.5. the soluble protein content of two varieties appeared up-trend at first and down-trend later, the rising rates and maximums of Huazhu No.4 were higher than XiangZhu No.1 after inoculation; soluble protein content did not change significantly 96 h later.These results indicated that Huazhu No.4 was more sensitive and had a significantly higher self-regulating ability and was more resistant to membrane lipid per oxidation.