Diversity and Spatiotemporal Distribution of Fungal Endophytes Associated with Citrus reticulata cv. Siyahoo.

Endophytic fungi are characterized as microorganisms found within internal tissues of living plants without any immediate, overtly negative effects. The present study was carried out to isolate, taxonomically characterize and determine the spatiotemporal distribution of endophytic fungi associated with leaf, stem, trunk, and root of mandarin (Citrus reticulata cv. Siyahoo). To do so, the sampling program was done seasonally in four geographically isolated mandarin growing areas of Hormozgan province of Iran, including Siyahoo, Ahmadi, Sikhoran, and Roudan. In total, 702 fungal isolates were obtained from leaf, stem, trunk, and root of healthy mandarin trees divided into 26 distinct morphotypes based on morphological characteristics. The morphotypes were taxonomically characterized through phylogenetic analysis of the ITS1-5.8S-ITS4 rDNA region sequences. Accordingly, 10 different fungal orders from 5 fungal classes were identified, i.e., Saccharomycetes (Saccharomycetales), Eurotiomycetes (Eurotiales), Dothideomycetes (Capnodiales, Pleosporales, Dothideales), and Sordariomycetes (Diaporthales, Hypocreales, Microascales, Togniniales), all from Ascomycota, which represented 97.2% and Ustilaginomycetes (Ustilaginales) from Basidiomycota which represented 2.8% of the isolates. The Aureobasidium pullulans, Penicillium citrinum, and Dothideomycetes sp. were the most frequent isolates. The trunk and leaf showed the highest and lowest total colonization frequency and species richness of endophytic fungi, respectively, in all sampling periods. The results showed that the colonization frequency of endophytes in Hormozgan province was higher in autumn than that in spring, winter, and summer. The trunk showed the maximum diversity of endophytes over all seasons. The Shannon-Wiener (H') and Simpson indices had significant correlation with sampling cites and tissue type and the maximum value of Shannon and Simpson indices (H' = 3.05 and 1 - D = 0.94) was found in the specimens collected from Siyahoo. In conclusion, the three factors (season, location, and tissue type) all in together could determine fungal endophyte composition of C. reticulata.

Genetic structure of Leptopilina boulardi populations from different climatic zones of Iran.

BACKGROUND: The genetic structure of populations can be influenced by geographic isolation (including physical distance) and ecology. We examined these effects in Leptopilina boulardi, a parasitoid of Drosophila of African origin and widely distributed over temperate and (sub) tropical climates. RESULTS: We sampled 11 populations of L. boulardi from five climatic zones in Iran and measured genetic differentiation at nuclear (Amplified Fragment Length Polymorphism; AFLP) and mitochondrial (Cytochrome Oxidase I; COI) loci. An Analysis of Molecular Variance (AMOVA) for the AFLP data revealed that 67.45% of variation resided between populations. No significant variation was observed between climatic zones. However, a significant difference was detected between populations from the central (dry) regions and those from the wetter north, which are separated by desert. A similarly clear cut genetic differentiation between populations from the central part of Iran and those from the north was observed by UPGMA cluster analysis and Principal Coordinates Analysis (PCO). Both UPGMA and PCO further separated two populations from the very humid western Caspian Sea coast (zone 3) from other northern populations from the temperate Caspian Sea coastal plain (zone 2), which are connected by forest. One population (Nour) was genetically intermediate between these two zones, indicating some gene flow between these two groups of populations. In all analyses a mountain population, Sorkhabad was found to be genetically identical to those from the nearby coastal plain (zone 2), which indicates high gene flow between these populations over a short geographical distance. One population from the Caspian coast (Astaneh) was genetically highly diverged from all other populations. A partial Mantel test showed a highly significant positive correlation between genetic and geographic distances, as well as separation by the deserts of central Iran. The COI sequences were highly conserved among all populations. CONCLUSION: The Iranian populations of L. boulardi showed clear genetic structure in AFLP profiles, but not in COI sequence data. The transfer of fruits containing Drosophila larvae parasitized by L. boulardi appears to have caused some unexpected gene flow and changed the genetic composition of populations, particularly in urban areas. Nevertheless, our results suggest that climate, geographic distance and physical barriers may all have contributed to the formation of genetically distinct populations of L. boulardi. Inevitably, there will be overlap between the portions of variance explained by these variables. Disentangling the relative contributions of climate and geography to the genetic structure of this species will require additional sampling.