Research On Transmission Of Grape Crown Gall Pathogens And Measures Of Disease Control

The grape crown gall is serious in grape planting. To solve this problem, effects ofthe measure of burying soil to prevent cold on occurrence of grape crown gall, itsmorbidity in the field, impacts of grape crown gall on pH of rhizosphere soil and thepopulation of microbe in rhizosphere soil were studied, the pathogens pattern wasidentified by the methods of molecular biology after isolating and culturing the pathogens;Meanwhile, spread way of pathogens in the body of plants and security of branchescollected from disease plants which were used as propagative materials were investigated.The report also researched the indoor and outdoor control effect of9different kinds ofagentia on grape crown gall. The resistance of nine grape varieties cultured in vitro togrape crown gall was compared. What’s more, the feasibility and reliability of characteridentification about the resistance of grape varieties cultured in vitro to grape crown galland a fast and reliable way to select resistant germplasm in vitro were explored.The main results are as follows:1. In this research, pH and population of microbe in rhizosphere soil of disease grapeplants and the adjacent normal ones were measured. The results indicated that pH ofrhizosphere soil of the disease plants was significantly lower than that of adjacent normalplants, and the number of fungi, bacteria, and actinomyces was significantly higher thanthe adjacent normal ones, which showed that pH of rhizosphere soil and population ofmicrobe were related to the incidence of grape crown gall.2. In coming-up period of the grape, bacterial strains were islolated from the xylomaand the soil on the wooden crown gall and shearing port in Kyoho grapevines and werecultured on medium in petri dishes. Those strains similar to the Agrobacterium wereselected for the biotype identification. PCR analysis was carried out for the strains by usingthe primers that related to the synthesis of Auxin and to the6b specific gene in Agrobacterium. Every material had isolated one strain showed the typical bands, whichcould be classified to the biotype of octopine.The results indicated that pathogens indisease tissues contaminated soil through rain or snow which became a reinfection sourceafter the disease plants covered with soil. While the soil pathogens could enter into theplant through shearing port or other ports, which further indicated that grape covered withsoil would aggravate the incidence of grape crown gall. Six of the strains collected fromcrown gall located on the basal part of the stems and on the roots in Kyoho grapevines hadbeen identified as pathogens, and the six strains also had been identified as the biotype ofoctopine.3. In the growing season of grape, we inoculated the biennial grape plants with thestrongest pathogenicity strain. After a month and a half, the aimed strains were detectedfrom the upper part of infective branches and the branch with crown gall using vacuumfiltration method, but none was decected from the lateral branch. Meanwhile, pathogenswere divided respectively from five branches which located on five different grapevineswhich were in the period of dormance, while pathogenicity strains were detected only onone branch. The two results above showed that either young branches or dormant branchescouldn’t be used as reproduction materials; after inoculated for a month and a half, L3strain was detected respectively from stem, leaf and crown galls of grape tissue cultureplantlets. Results of experiments in laboratory and in field both showed that pathogens hadbeen spread to other parts with the sap. In the bleeding period of grape, pathogens weredivided respectively from bleeding sap of five disease grapevines, in two of which theaimed strains were detected. Infection and spreading of pathogens with the sap began inthe bleeding period.4. The strain with the strongest pathogenicity was screened out by inoculated into thestem of the sunflower seedlings. Then, the bacteriostasis of nine bactericides or antibioticswas tested to this strain by using the inhibition zone method. The results showed that72%streptomycin sulfate for agricultural use grade with the200times dilution had a significantinhibition to the growth of the strain; followed by trichloroisocyanuric acid and80%ethylicin. The rest ones including20%thiodiazole-copper,80%carbendazim,3%zhongshengmycin,40%cocide,2%kasugamycin, and25%bismerthlazol showed nosignificant effect on the inhibition. The results of experiments conducted in the fieldindicated that72%streptomycin sulfate for agricultural use grade with the1000timesdilution,80%ethylicin with the200times dilution, anhydrous cupric sulfate with the100times dilution could reduce disease occurrence, and the relative control effect could get to79.6%,74.2%,71.3%respectively.72%streptomycin sulfate for agricultural use had themost obvious effect among them.6. Agrobacterium strains L-R and L3were inoculated on seedlings of nine grapevarieties in vitro, which were Wink,Sweet Scarlet,Beichun,Flame,Crimson,Autumn seedless,Autotetraploid grape Muscat Hamburg,Summer Royal,Melisa.Nodulingpercentage and tumor weight were investigated at45thday after innoculation. Theresistance of the materials was evaluated based on noduling percentage and tumor weight.The disease rate of all varieties inoculated by the two strains were all more than73.3%.Theresults indicated that there were no completely immune varieties. The noduling percentageand tumor weight of Wink were lower than other varieties, thus, its resistance was higherthan other varieties. This method could reflect resistant level of different varieties to grapecrown gall, and it could be used in grape crown gall sensitivity evaluation and resistantgermplasm selection of grape varieties.