Diversity Of Grass Endophytic Fungi Of Guizhou Tall Fescue

Tall Festuca used as forage grass is also called Festuca arundinace,and has been cultivated in China’s Xinjiang and the moist area of middle Northeast. It usually has more extensive applicability, and is excellent lawn grass and forage grass(Mu Qiong 2008). Wu Jiahai and others(2006) collected wild tall fescue and by using modified mass selection cultivated Festuca arundinace Qian grass No.1 that is applicable to Guizhou, which is the plant of high fitness, with dark green leaf, more tillering number, long green period, strong stress resistance, good fecundity, spike-shape compact. It has a significant demonstration significance and economic value to grassland construction, returning farmland to grass, ecological governance and animal husbandry in Karst area.Grass endophyte fungi refer to the microorganisms that can complete its partial or whole life history in gramineous grasses, and does not cause any symptom of disease. Grass endophyte fungi universally exist in all kinds of gramineous plants(Latch et al., 1989), on one hand they sojourn in the intercellular space of grass for parasitic life; on the other hand, they can promote the growth of grasses, enhance stress resistance of grass to reach a mutual symbiotic relationship with parasitic grass(Li et al., 2007). The current researches on endophytic fungi of grasses mainly concentrate in the ascomycota pyrenomycetes hypocreales ergot bacteria genus epichloe and its anamorph(Neotyphodium), the endophynic fungi of anamorph grass, due to its extensive infection and special function to grass plant, has higher scientific research value(Nan Zhibiao et al., 2004).This research takes samples of tall fescue planet collected from the territory of Guizhou and planted in Guiyang tall fescue garden plants, using optical microscope for microscopic observation, determines the endophytic fungi infection situation, and at the same time studies using tissue sections staining technique the tall festuca endophytic fungi distribution characteristics; and then by in vitro tissue culture technology, isolated cultures endophytic fungi, and conducts morphology, physiology, biochemistry and molecular biology identification to them, and provides important theoretical and technical basis for the future study of relationship of tall fescue endophytic fungi and their hosts, for tall fescue seed breeding using endophytic fungi.Research results are as follows:1.Colonization and tissue distribution of endophytic fungiEndophynic fungal infection rate in each tissue of tall fescue is different, but all present same infection trend, namely: seed infection rate > stem infection rate> infection rate of leaf sheath > > the infection rate, the infection rate of seeds was about 35% and the stem infection rate is about 21% leaf sheaths, infection rate is about 18%, the leaf infection rate is about 7%. in the sample of tall fescue leaf, leaf sheath, stem section, observed the endophytic fungi mycelium is common: close to the cell wall growth, most of the host cell parallel to the long axis, occasionally arranged in single cell gap, thickness comparison even almost no local bifurcation, occasionally bending, not penetrate the host cell. The endophytic fungi in leaves extended along the direction of growth of the spongy tissue, and more in the near stomata in leaf and sheath; more sparse, sheath mycelium along the veins parallel to the direction of the row column, vertical growth; stem section of the mycelium near the vascular bundle, irregular arrangement, and the distribution is relatively dense, often forming a dense network.2. Endophytic fungi separation and identification of tall fescueBy tissue block separation method, we determined the optimum separation conditions of endophytic fungi in different tissues of tall fescue, and isolated 229 strains of endophytic fungi from 600 tissue blocks in three kinds of tall fescue. The isolation rate is 38.17%, combining by morphological type, we eventually got the 18 strains of single filamentous fungi. After molecular, morphological and physiological and biochemical identification, these fungi belong to epichlo, aspergillus and penicillium fungi of the genus.3.Resistance of endophytic fungi to low temperature stressThrough microscopic examination, distinguishing experimented tall fescue into endophynic fungal infected(EI) and non-endophytic fungal infected(EF) plants, and collecting seeds separately, by culture dish paper germination method, setting three temperature treatment of 25℃, 15℃, 5℃, it was found that with the droping of ambient temperature, EI seed and EF seed germination index, germination rate, plumule and radicle length all showed a downward trend. In 5℃, the condition of low temperature, EI seed germination was higher than that of EF seed germination.