The role of endophytic fungi in drought resistance of Lolium perenne in Iran

摘要

It has been long that the symbiotic relationship among some members of poaceae family and endophyte fungi has been identified and under focus. They belong to genus Epchloe (Clavipitaceae), which reside in the leaf sheath of Lolium perenne. The presence of endophytes in a plant leads to its resistance to a range of biotic and abiotic stresses. To conduct the study, more than 640 fresh plant materials (Natural samples) of Lolium perenne, of which 32 had endophytes, were collected from the native rangelands in north-east, west, north and northwest of Iran. To insure the presence of fungal endophyte in the samples, leaf sheaths were stained with Rose Bengal. The genomic DNA was also extracted from the isolates to confirm the identity of fungi. Accordingto the morphological characteristics and specific primers, all the isolated fungi from Lolium perenne were identified as Epichloe endophytes. Then 32 endophjrte-infected genotypes and 32 endoph)^e-free genotypes of Lolium perenne were planted in a farmin Islamic Azad University of Bojnourd. In order to study the role of endophytic fimgi in drought resistance of Lolium perenne, an experiment was conducted in a randomized complete block design with two replications. To impose the drought stress, after determining the FC and PWP and drawing the moisture diagram, when the soil moisture reached 40% of the field capacity, the field was irrigated with a volume of water that was calculated during the experiment appropriate with the root depth. In the presentstudy, height, crown, dry weight, leaf length, leaf width, wet weight, number of tillers and leaf water content were measured. To analyze the data, SAS was employed and to compare the means LSD was used. The WARD was used to cluster-analyze the data andthe Stat Graphic was used to draw the biplot. The stress conditions reduced all traits except leaf width and water content and this reduction was significantly lower in endophyte-infected genotypes. In other words, under the stress condition, endophyte-infected samples had higher tillers number, dry weight, crown, leaf length and wet weight. The cluster analysis separated the genotypes into 3 groups in the normal condition and four groups in the stress condition. The endophyte-infected genotypes and endophyte-free genotypes were accurately isolated. Most of the genotypes infected with endophytes were in the second group in normal condition. Enjoying most of the traits, the genotypes of this group had a better average than the other groups. The genotypes of this group are a very suitable source for breeding and performance increase.