Study On The Charcteristics Of Locoweed Endophyte In 3 Species Of Oxytropis From Seeds To Plants

Poisonous plant species of Oxytropis and Astragalus is common named as locoweed.Locoweed endophyte（Alternaria sect.Undifilum spp.）is the reason for their toxicity.Up to data,the fungi transmit into next generation from seeds.However,how grow into various tissues of plants,and what is the effect to plant growth is still did not determined.The object of this thesis is to study the characteristics of endophyte in Oxytropis ochrocephala,O.glabra and O.kansuensis from seeds to plants.The main results are as follows:1.Percentage of seeds containing endophyte were 80.00%,78.50%and 34.00%respectively,which no significant relationship to the germination percentage（P>0.05）.2.No difference were found between the plants developed from embryos after remove seedcoats with endopyte and the plants from embryos that seedcoats wihtout endophyt for the percentage survival in 4 wk,dry weight in 4 months and mortality in 8 months.This imply that endophyte did not affect development of embryos and late plants.3.Percentage of plants containing endophyte was 88.89%,66.67%and 26.67%,respectively,cultured with whole seeds（did not removed seedcoats）when endophyte presented,and isolated and PCR detected with specific primers of locoweed endophyte.This means not all containing endophyte seeds can developed to containing endophyt plants,depended on locoweed species.4.Characteristics of endophyte growth in plant tissues were from stems to petioles,and then into leaf blades,and from plant basal to tip,as plant became higher and bigger,but different for O.ochrocephala and O.glabra,for O.ochrocephala,distributed uniformly,but for O.glabra,were free from some individual shoots,not even.No conidia producted on the surface of survive plants and leaf blades kept in moisture condition,while,lots of conidia produced when the segements of stems and petioles vertically placed into PDA,which can used in later inoculation.5.Endophyte significantly（P<0.05）decreased the shoot dry weight,root dry weight,and leaf net photosynthetic rate,transpiration rate and stomatal conductance of 2 species of locoweed,O.ochrocephala and O.glabra,compared with plants contained endophyte and free from the fungus.However,endophyte did not affect（P>0.05）those indicators of O.kansuensis and hight of O.ochrocephala and O.glabra.Therefore,endophyte have no promotive function to locoweeds.6.Swaisonine content assayed with LC-MS in plants with endophyte(O.ochrocephala,O.glabra and O.kansuensis was 108.59 mg?kg^-1,138.30 mg?kg^-1 and 151.51 mg?kg^-1)was higher than in plants free from endophyte(10.44 mg?kg^-1,7.28 mg?kg^-1 and 7.78 mg?kg^-1).