Isolation And Identification Of Ustilago Esculenta And Preliminary Study On Its Interaction With Zizania Latifolia

Zizania latifolia is an aquatic herb for many years,which is mainly distributed in the east of Asia.It is the second largest aquatic vegetable in China.Ustilago esculenta belongs to basidiomycetes subfamily,whose infection can cause the stem to expand and form edible water bamboo.The formation of the succulent stem of Zizania latifolia is closely related to the infection of Ustilago esculenta.The swelling process of the succulent stem of Zizania latifolia is the process that Ustilago esculenta infects Zizania latifolia and grows in it to induce a series of stress responses of Zizania latifolia.In this study,two species of Ustilago esculenta were isolated and cultured in vitro,and the morphology and molecular identification of the two species were carried out;the morphology and biological characteristics of Ustilago esculenta were studied;the effects of different carbon sources and p H on the growth of the two species of Ustilago esculenta were analyzed in vitro;the differences during the expansion of Zizania latifolia with different phenotypes were preliminarily analyzed.The main results are as follows:1.In this study,M-T(mycelia-teliospore)type and T(teliospore)type of Ustilago esculenta were successfully isolated from normal Zizania latifolia and gray Zizania latifolia.Through morphological identification and ITS-5.8s DNA molecular identification by universal primer amplification,the sequences of the two isolates were compared with those of Ustilago esculenta in known NCBI,and the homology was more than 99 %.Compared with M-T-type Ustilago esculenta,there are substitution and insertion of some bases in the sequence alignment of T-type Ustilago esculenta.2.Further study on T-type and M-T-type showed that there was a big difference between them.T-type of Ustilago esculenta had stronger adaptability in different carbon source culture medium,and was more able to bear the influence of nutrition factors.At different p H,the M-T type of Ustilago esculenta is more sensitive.under the same condition of carbon source or p H,the growth rate of T-type smut was significantly higher than that of M-T-type of Ustilago esculenta.3.The morphological changes of the fleshy stem of Zizania latifolia and Zizania latifolia were significantly different before and after pregnancy.The length,transverse stem and net weight of the fleshy stem of Zizania latifolia were significantly larger than those of Zizania latifolia.During the expansion of Zizania latifolia,a large number of smut bacteria began to proliferate before it was pregnant.Smut bacteria usually existed in the form of mycelium in the stem of normal Zizania latifolia,and only sporadic winter spores appeared in the later stage of pregnant Zizania latifolia,while smut spores spread throughout the whole development period after pregnant Zizania latifolia.The cavity size of the succulent stem of Zizania latifolia is directly proportional to the number of spores of the Ustilago esculenta.4.The changes of carbohydrate content and glycozyme in normal Zizania latifolia and gray Zizania latifolia showed that the contents of sucrose,fructose,starch,total soluble sugar and glucose in normal Zizania latifolia and gray Zizania latifolia had significant differences.The carbohydrate content in the fleshy stem of Zizania latifolia increased rapidly when it began to expand,but decreased at the later stage of maturity.Due to the existence of a large number of smut fungus in Zizania latifolia,the content of total soluble sugar,sucrose,starch and glucose in the flesh stem of Zizania latifolia was lower than that of normal Zizania latifolia,and the difference was significant.During the expansion of Zizania latifolia,the acid invertase activity of normal Zizania latifolia and gray Zizania latifolia decreased,and the SPS activity of normal Zizania latifolia and gray Zizania latifolia increased rapidly first and then decreased,which was related to the proliferation of Zizania latifolia.