High genetic diversity in an endemic and vulnerable species: evidence from Astragalus cyclophyllon (Fabaceae) in Iran

Abstract

The genus Astragalus L. with about 3000 species is the largest genus of flowering plants. It is also the largest genus in the flora of Iran with more than 850 taxa. Astragalus cyclophyllon Beck is an endemic taxon belonging to Astragalus sect. Incani DC. It occurs scattered in the steppe and semi-steppe areas of the western and central parts of Iran. This species is one of the most important forage taxa of Astragalus. According to IUCN criteria it has been classified as a vulnerable taxon in Iran, as it occurs in habitats intensely used by herders for their livestock. Here we evaluate the genetic diversity of the populations of this species in Iran to see whether genetic diversity is high or if reductions have already happened. For this purpose, sampling was done in all geographical areas with A. cyclophyllon populations in Iran. In total, 80 individuals representing 29 populations were studied using 33 quantitative and qualitative morphological characters and 10 inter-simple sequence repeat (ISSR) primers. ISSR revealed 240 bands which all were polymorphic. Neighbor-joining cluster analysis divided the individuals in four groups, Principal Coordinate Analysis and Bayesian population assignment analysis in Structure resulted in three genetic units. Morphological variation showed no correlation with the molecular data. The mean of Gst and Nm indices are 0.516 and 0.468, respectively, which indicate a very high genetic differentiation and low gene flow between the studied populations. According to these results, we conclude that genetic diversity is high in this species and that, therefore, the major threat for A. cyclophyllon is currently not related to inbreeding depression in populations, but might be due to livestock grazing that could change the population demographic structure by reducing regular establishment of new offspring.

Molecular Variation in Some Taxa of Genus Astragalus L. (Fabaceae) in the Iraqi Kurdistan Region

“…The present work identified 14 ISSR markers with PIC values higher than the mean PIC value, which may prove useful for future trait mapping and tagging research involving Iraqi Astragalus taxa. In this regard, lower values of PIC were reported for Astragalus species in other studies in Iran (0.31-0.37) [16] and Romania (0.34) [48].…”

“…Three distinct Astragalus species populations were stated for the ISSR markers; however, only two populations were defined for the CDDP markers, similar to the work conducted on Astragalus exscapus using an eight-pair combination of SRAP markers [48]. In Iran, 10 ISSR markers were used to separate the A. cyclophyllon population into three subgroups, in support of these findings [16].…”

“…CDDP molecular markers are a cutting-edge method that amplify the entire plant genome with primers based on conserved DNA sequences, producing bands and targets mostly related to biotic and abiotic stress. Many molecular markers, such as ISSR [15,16] and SRAP [17], have recently been used to examine phylogenetic relationships in Astragalus species. Aside from the utility of the previously mentioned markers, a new form of marker known as CDDP has emerged as a valuable tool for measuring diversity in various plant species [18][19][20].…”

“…Aside from the utility of the previously mentioned markers, a new form of marker known as CDDP has emerged as a valuable tool for measuring diversity in various plant species [18][19][20]. There have been considerable efforts in Turkey [21][22][23] and Iran [16,24] regarding the morphological diversity hub for Astragalus species.…”

Genetic Diversity of the Endemic Species Phanera sirindhorniae in the Mekong Basin of Thailand Based on ISSR Markers

“…This design enables the amplification of DNA fragments between closely proximate SSRs, facilitating the examination of polymorphisms at multiple locations rapidly, easily and affordably [12][13][14]. ISSR techniques have been applied to studies of various endemic plant species within the Fabaceae family, such as Astragalus cyclophyllon [15], Hedysarum theinum [16] and Humboldtia brunonis [17], as well as other endemic plant species like Hertia cheirifolia [18], Rhabdosciadium aucheri [19] and Rhynchostylis retusa [20].…”