The Evaluation Of Different Kiwifruit Varieties’ Resistance To Canker

The domestication of Kiwifruit from wild to commercial cultivation is the most successful plant domestication example in the 20th century. Kiwifruit have drawn wide attention by the society, because of its unique taste, abundant nutrient, high economy value and good medical effect. China is rich in kiwifruit germplasm resources, while the cultivation history and the time of commercial cultivation are not long enough. Nowadays, bacterial canker disease of kiwifruit occur wildly in China, and it goes serious year by year. Bacterial canker disease of kiwifruit is a fatal disease to kiwifruit for its huge threat to the production and development. Occurrence of the disease have characteristics of wide range, speedy spread, high pathogenicity and difficulty in prevention and cure. The disease can cause vast death in short time and it has now been listed in China Forest Plant Quarantine Disease. At present, Further study of pathogenic mechanism of pathogenic bacteria have not been taken worldwide, thus there is no effective way to prevent the occurrence of the disease.So, to screen high resistance germplasm resources to get rid of bacterial canker disease has become the most critical task we now face. By vaccinating bacterial canker disease pathogenicity on different kiwifruit species and measuring relative parameters, the experiment comprehensively evaluated kiwifruit resistance to canker disease, aiming to screening some germplasm resources with high resistance, and to preliminary establish kiwifruit resistance evaluation system, so that the result could support the sustainable development of kiwifruit with technology way, and promoted the healthy development of kiwifruit production.This experiment was conducted to study the following aspects:(1) In vitro conditions, we inoculated branches of hongyangkiwifruit and 23 other varieties with canker pathogens under different pathogenicity, inoculation concentration, cultivation humidity, and inoculation methods. By doing this could we discuss the canker pathogens infection effect on kiwifruit branches in different conditions, and could we evaluate resistance to canker from different kiwifruit branches.(2) we inoculated canker pathogens on potted seedlings of white, bruno and hongyang, and then, we measured related physiological parameters between inoculated plants and control plants, so that we evaluated resistance on canker from different kiwifruit varieties and the relation between related physiological parameters and anti-canker capacity.(3) By measuring and observing lignin, lenticels length, density and the arrangement of lenticels of healthy kiwifruit plants of hongyang,hayward, green meat plus trees(G-HZ201202),bruno,miniwhite,xuxiang and white, we evaluate the relation with the anti-canker capacity between species.(4) To assure infected symptoms after inoculation on kiwifruit branches and leaves are caused by bacterial canker disease of kiwifruit, we used branches and leaves infected by canker pathogens, separated pathogens by Tissue isolation method and Streak plate method, culture on LB liquid medium, extract DNA of pathogens and identify pathogens type according with the 16s-23S rDNA ITS Sequence analysis of Specific primers amplification.The main results are as follows:1. Resistance to canker from different kiwifruit varieties had remarkable differences, and different inoculation condition showed remarkable effect on the disease index of kiwifruit branches. Among the branches of 24 varieties, white and xuxiang showed high resistance, miniwhite, jinkui, excellentgreenflesh (G-HZ201201) and maoxiong showed resistance, and dahong, zaoxian, zaoyan and Excellentyellowflesh Y-HZ201201 showed highly susceptible characteristic. Pathogens with high pathogenicity, high concentration, high humidity, and wound area of branch all had remarkable effect on the disease index of kiwifruit branches.2. Physiological parameter showed linear correlation in different levels with disease index among different kiwifruit species. Enzymatic activity of CAT, PPO, PAL, POD and SOD, content of total phenolic、soluble protein、soluble sugar, and lignin, along with lenticel length, density, and the arrangement of lenticels, all could take as physiological parameters in identifying kiwifruit anti-canker. Among these, CAT, PPO, content of total phenolic and lignin, lenticel length, and density had remarkable correlation with disease index, so we could take these as important parameters in valuing kiwifruit anti-canker.3.The bacterial strains separated from infected branches and leaves of kiwifruit were proved the same. Their DNA fragment size and sequence were totally the same with variety kiwifruit affected by Psa. The infected symptoms kiwifruit branches and leaves showed after inoculation were caused by bacterial canker disease of kiwifruit.