Biocontrol Of Watermelon Wilt Disease And Expression Analysis Of Resistance-related Genes Of Watermelon

The vascular wilt fungus Fusarium oxysporum f.sp. niveum is a soilborne facultative parasite that causes economically important losses in a wide variety of watermelons in China. F. oxysporum has four races:RaceO,1,2and3. The pathogen can penetrate the root of the watermelon and develop in the vascular system, followed by the secretion of phytohormore, cell wall-degrading enzymes and toxins which can cause great damage to the plant. In contrast to that, watermelon can synthesize callose which blocks the development of the pathogen. Some biological agents have been used to control F. oxysporum, such as Trichoderma, Arbuscular Mycorrhizal, non-disease F. oxysporum, Bacillus, endophyte fungi and so on. Among them, B. subtilis is the most potential one which has not been applied on a large scale. And because of the lack of genomic information in watermelon, the study on cloning resistant genes in watermelon develops slowly. In the present study, we evaluated the biocontrol efficacy of B. subtilis and compared with Piriformospora indica and Sebacina vermifera. Our result indicated that B. subtilis wettable powder (WP) can control the watermelon wilt disease efficiently, while P. indica and S. vermifera show some potential in controlling the disease. Different apply methods shows different biocontrol efficacy, and irrigation root method gets the best results. Our results also show B. subtilis, P. indica and S. vermifera can contribute to plant growth and development and irrigation root using P. indica can obtains the best effect. Using different methods applying B. subtilis have different effects in controlling watermelon wilt disease. Using B. subtilis in hole-application method works best.We also have cloned the cDNA of CINPR1, ClPRla, CIACO1and ClACSs. In order to study the expression patterns of watermelon resistance-related genes, we analyze the expression of CINPR1, OPR1a, CIPR3, CIERF1, ClERF4, CIERF5and ClACO1in different tissues, different growing stage and different treatment such as phytohormone and F. oxysporum. The results showed there is no significant expression difference in different tissues and growing stage, except CIERF1has high expression level in leaf during four to six leaves. When treated with S A, JA and ACC, the expression of resistance-related genes in watermelon increased to some extent.In conclusion, B. subtilis wettable powder (WP) can control the watermelon wilt disease efficiently, while the endophyte fungi P. indica and S. vermifera shows potential in controlling watermelon wilt disease. Our research provides a new method for controlling watermelon wilt disease. Besides, cloning resistance-related genes in watermelon will help us in studying the mechanism of disease resistance.