Preliminary Study On Diversity And Antimicrobial Activity Of Endophytic Fungi Isolated From Juglans Regia L. In Shaan Xi

The endophytic fungus is very abundant and has been valued in recent years. Researchers focus their study on the plants of medical value. Walnut as one of the widely cultivated is planted in the world. Walnut green husk, root extract has anti-cancer, bactericidal and insecticidal efficacy. Walnut leaf extract has detoxification and can relieve itch. It explained that walnut had a good medicinal value. Therefore, research of endophytic fungi of walnuts is of great significance to the development and utilization of microbial pesticides. In this study, materials were collected from different tissues and organs of healthy walnuts in three different climatic zone(Shan yang, Lantian, Yijun) in shaan xi. The separation of endophytic fungi was used tissue separation. Classification and identification of endophytic fungi was used classical methods and molecular biology method and the bacteriostatic activity of endophytic fungi was studied. The results were as followings:1. Endophytic fungi of walnut were isolated by using tissue separation and purified by using PDA. A total of 1450 strains of endophytic fungi were isolated. As a result of morphological classification and fungi r DNA- ITS regional, it was identified that they belong to 47 genera, of which Alternaria was the highest, amounting to 20.00% of the total. Fusarium and Saccharomyces took a portion of 8.34% and 8.14%.2. By the analysis on species diversity of endophytic fungi in the walnuts, we found that the distribution and compostion of endophytic fungi varied with plant organs, habitats and seasons, and a certain extent of regularity was also presented. The results were as followings: The isolation rate of endophytic fungi in two-year-old twigs was the higtest in all samples and reached 29.03%, while the isolation rate in one-year-old twigs was evidently higher than other tissues and reached 27.03%. The principle of the rest of organization was: Scapus(14.90%) > root(14.76%) > leaf(8.83%) > fruit(5.45%).3. The highest Shannon-Wiener diversity index and evenness in two-year-old twigs from which 421 strains of endophytic fungi belonging to 25 genrea were isolated were 1.15 and 0.36 respectively, and the lowest, which were isolated from fruits, were 0.27 and 0.11 respectively. Among the comparion in three habitats, the isolation rate, the highest Shannon-Wiener diversity index and evenness in shanyang reached 39.52%, 1.42 and 0.42, which were evidently higher than 33.03%, 1.25 and 0.39 in yijun and 27.45%, 1.15 and 0.34 in lantian, respectively. As for the isolation rate in different seasons, the isolation rate in winter reached 46.21%, which was evidently lower than 53.79% in autumn.4. There were some similarities between different populations of endophytic fungi. Populations of endophytic fungi between one-year-old and two-year-old twigs showed the highest similarity(0.7755), and the lowest was 0.3333 between roots and scapuses; The similarity of endophytic fungi of walnuts isolated from three habitats were above 0.500. Among the three habitats, populations of endophytic fungi between lantian and yijun showed the highest similarity(0.6415); Populations of endophytic fungi between autumn and winter also showed a certain extent of similarity(0.5714).5. There were different degrees of antifungi activity of endophytic fungi isolated from walnuts.The endophytic fungi isolated from walnuts agianist at least one pathogenic fungi more than 75% occupied 19.9%. The inhibition rate against Sclerotinia sclerotiorum and Phytophthora capsici were all above 50%. The results showed that the inhibition rates of LT7、LT11、DLT3、YJ2、YJ9、YJ17 against 6 pathogenic fungi were generally good. The inhibition rates of LT7 against 6 pathogenic fungi were above 80%, and T11、DLT3、YJ2、YJ9、YJ17 against at least 3 pathogenic fungi were above 75%. Therefore, the endophytic fungi of walnuts had a broad antifungi spectrum.