THE ROLE OF ENDOPHYTIC FUNGI IN DROUGHT RESISTANCE OF LOLIUM PERENNE IN IRANVahid Jajarmi, Mohamad R. Bihamta, Mohamad R. Sabzalian, Islam Majidi and Farrokh Darvish
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. According to the morphological characteristics and specific primers, all the isolated fungi from Lolium perenne were identified as Epichloe endophytes. Then 32 endophyte-infected genotypes and 32 endophytefree genotypes of Lolium perenne were planted in a farm in Islamic Azad University of Bojnourd. In order to study the role of endophytic fungi 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 present study, 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 and the 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. The isolation of the endophyte-infected and endophyte-free genotypes was properly carried out in the stress conditions of the cluster analysis and the endophyte-infected genotypes could go in the first group. Most of the endophyte-free genotypes could fit in the third and fourth groups. The trait mean of the endophyte-free groups was lower than that of the other groups being in symbiotic relationship with endophytes. The factor analysis also determined two factors that accounted for 78.76% of variation in the normal condition. In the genotype dispersion observed and evaluated in normal conditions, four groups were indentified. The main factor included the number of tillers, dry and wet weight. The coefficients in the second factor included the leaf width that had a lower value in the first factor. In terms of both the factors, the genotypes that were at the end of the first quarter on the plot stood at a better level compared with the other genotypes where, in addition to the endophyte-infected genotypes, there were some of the endophyte-free genotypes. Finally, under the stress condition, the factor analysis determined two factors that accounted for 85.62% of variation where the main factor included the number of tillers, dry and wet weight and leaf length. The coefficients in the second factor included the leaf width that had a lower value in the first factor. The genotype dispersion showed that most of the genotypes having endophytes were in the first quarter which, based on both the factors, stood at a very desirable level. One genotype that included endophytes could fit in the end part of the first quarter which, compared with the other genotypes, could stand at a better level. According cluster analysis and facto analysis, the trait average of the endophyte-free groups was lower than that of the other groups being in symbiotic relationship with endophytes. It can be concluded that the endophytes in normal and stress conditions can help increase the traits effective on performance.
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