Induced Systemic Resistance Of Endophytic Bacteria In Hami Melon

Some endophytic bacteria strains of good induced effect were screened for their ability of inducing systematic resistance to Hami melon Plant. The paraments of inoculating method, inoculating concentration, duration time and inoculating period were explicited in trial. The mechanism of induced systematic resistance of endophytic bacteria has also been discussed. This paper provides a scientific basic for the exploitation and utilization of biological control resourses.Hami melon inoculating endophytic bacteria can delay the initiation of disease and decreased the disease index. The results showed that 15 strains expressed the ability of induced resistance of Hami melon Plant to Pseuodomonas syringae pv.melonis, 12 strains expressed the ability of induced resistance to Phytophthora drechsleri, 7 strains expressed the ability of induced resistance of Hami melon Plant to both of the pathogens,by the standard of 30% effect of inducing resistance. Its indued effect is steady continually. The results showed that the effects of endophytic bacteria,chemical elicitors and SA on induced resistance against both of the pathogens was increased. Hami melon foliages were investigated. No significant difference was shown between endophytic bacteria,chemical elicitors and SA.257 strain inoculated 2×108cfu·mL-1 concentration can activate Hami melon defense system and induce disease resistance. Different inoculating method are compared, the result shows that the irrigating root method is the best. The irrigating root method is better than that spraying method and dipping root method. The treatment of reinoculating endophytic bacteria has a better induced effect. The duration was prolonged during induced effect decreasing.The alive thalli, inactivated culture,cell wall extraction and LPS of endophytic bacteria strains can enhance the capability of induced resistance of Hami melon Plant to both of the pathogens.The results showed that increase of PPO,POD and PAL enzyme activities and the number of the enzyme bands in Hami melon foliages were excited inoculated endophytic bacteria strains, and the enzymes activities were related to its disease resistance. These defense enzymes play a role in the course of the induced resistance, their synergisitic action enhanced capability of disease resistance.This experiment proves that the content of total phenolics in Hami melon leaves after being inoculated endophytic bacteria is higher obviously and strengthen the defense system against disease. Meanwhile the content of MDA in Hami melon leaves after being inoculated endophytic bacteria was decreased obviously, It enhanced the ability of resisting pathogen and aggravated anti membrane lipid peroxidation of cell. Ultrastructural feature of leaf cell after being inoculated endophytic bacteria was changed. The structure of Hami melon prevented disease original from inroading bolt body and extending.230,257,261strain with better induced resitance effect of the complex infection were screened out. They were preliminarily classified as Bacillus spp., Erwinia spp.. Based on the results of signature sequences of 16SrDNA, bacteria morphology and physiological and biochemical assessmen, 257 strain may be identified as Bacillus Thuringiensis.257 strains were screened of endophytic bacteria for their ability of inducing systematic resistance to Hami melon Plant. The growth and development of Hami melon was promoted. It has broad development and utilization prospects of new pattern elicitor. But the mechanism and signal transduction of induced resistance need to be researched and proved.