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High-altitude regions like the Himalaya, where various slopes are present on a very small spatial scale, are one of the best natural laboratories for investigating how genetic diversity and population structure are distributed across altitudinal gradients. In this study, we investigate the magnitude of genetic diversity and population structure of Rhododendron anthopogon D.Don along an altitudinal gradient in the Kashmir Himalaya. We used the start codon targeted (SCoT) marker to evaluate the genetic diversity and differentiation between different populations across five sites along an altitudinal gradient ranging from 3200 to 4000 m (amsl). Our results demonstrate that the magnitude of genetic diversity differs among the populations of R. anthopogon along the altitudinal gradient. We observed a decreasing trend in genetic diversity with increasing altitude from site-1 to site-3 (3200 to 3600 m), and an increasing trend from site-4 to site-5 (3601 to 4000 m). Furthermore, we also observed the highest genetic diversity at upper altitude (site-5) and the lowest at mid-altitude (site-3). Our results reveal a high genetic differentiation (Gst = 0.7349) and a low gene flow (Nm = 0.1804) among the populations. Analysis of molecular variance (AMOVA) reveals 71% variation among the populations and 29% variation within the populations. We also reveal positive associations between geographic and genetic distances, indicating isolation by distance effect across all altitudes. STRUCTURE and cluster analysis divided all the populations of R. anthopogon into five clusters according to their geographical location. Overall, the study adds to our understanding that altitude is the major driver of genetic variation and differentiation between populations of R. anthopogon which may help increase its range under ongoing projected climate change. Our study also reveals that populations at higher altitudes are not genetically isolated, suggesting that they might be an essential source for migration in the era of climate change. [ABSTRACT FROM AUTHOR]

Parrotia persica (Hamamelidaceae) is a relict tree species restricted to the Hyrcanian district of Iran and Azerbaijan. Parrotia had a wide Eurasian distribution before the Pleistocene glaciations and the western Eurasian P. persica diverged from its East Asian sister species P. subaequalis during the Miocene. We investigated infraspecific genetic diversity and structure in 10 populations of P. persica using SCoT molecular markers. We determined a significant genetic diversity in the genomic DNA using AMOVA, which mainly to diversity among populations. Moreover, high levels of genetic differentiation (Gst), total genetic variation (Ht), and a low rate of gene flow were recorded between populations. In some populations, high levels of genetic polymorphism resulted from frequent mutations in their members. The Mantel test showed a significant correlation between genetic diversity and geographic distance. We found three genotype groups among the populations using STRUCTURE and clustering analyses. These genotypes did not conform to specific distribution patterns. Our results indicated that fragmented and small-sized populations, a flat rate of gene flow, a low rate of mutations, and the breeding system in Parrotia led to high levels of population differentiation along with a nearly uniform genetic structure in most populations. Three main diversity centers exist for Parrotia in Hyrcanian forests, which are of importance for conservation strategies. A comparison with previously published population genetic patterns in Hyrcanian relict tree species (Zelkova Spach and Pterocarya Nutt. ex Moq.) suggests that these have different genetic structures with higher rates of gene flow between populations. The detected genotypes can be used to generate new genotypes by cross pollination, and also they can cultivate as avenue trees and parks in urban areas around each genotype to conserve biodiversity in this species. [ABSTRACT FROM AUTHOR]

Date palm (Phoenix dactylifera) is an important crop plant both from nutritional and economic points of view. The assessment of genetic diversity and population differentiation of date palms are evaluative for its dynamic conservation and sustainable utilization of its genetic diversity. Estimates of genetic diversity based on molecular markers and fruit characteristics were performed in samples of 23 date palms growing in Ahvaz city (Khuzestan province of Iran). Clustering based on fruit morphological features separated the cultivars in different groups. These cultivars differed significantly in morphological features (P = 0.001). Start codon targeted (SCoT) polymorphism markers revealed a good level of genetic variability (10.17 to 45.76%) in these cultivars. Moreover, STRUCTURE analysis revealed the presence of within-population genetic variability. Analysis of molecular variance revealed a significant genetic difference among date palms, while it showed a higher degree of within-cultivar genetic variability compared with that of among-population diversity. Some degree of common shared alleles occurred between date palm cultivars. Gst versus Nm analysis showed that some of the SCoT markers have a high discrimination power and may have a potential local adaptive value. The Mantel test showed a significant association (r = 0.40, P = 0.001) between morphological and genetic distances. Therefore, both morphological and SCoT molecular data can be used in genetic screening of date palms in the available germplasm. [ABSTRACT FROM AUTHOR]