Simple sequence repeats marker polymorphism in emmer wheat (Triticum dicoccon Schrank): Analysis of genetic diversity and differentiation

Abstract

Genetic diversity was investigated in 73 accessions of emmer wheat (Triticum dicoccon Schrank) from 11 geographical regions using a set of 29 simple-sequence repeat (SSR or microsatellite) markers, representing at least two markers for each chromosome. The SSR primers amplified a total of 357 different alleles with an average of 12.31 alleles per locus. The number of fragments detected by each primer ranged between 6 (Xgwm1066) and 21 (Xgwm268). Null alleles were detected in nine of the 29 primers used. A high level of gene diversity index was observed. Across the 29 primers, gene diversity ranged from 0.60 (Xgwm46) to 0.94 (Xgwm655), with a mean of 0.82. There was a highly significant correlation (r = 0.882; p < 0.01) between gene diversity index and the number of loci, showing the number of loci per se is a strong indicator of diversity. Analysis of genetic diversity within and among eleven geographical regions revealed most of the genetic diversity of the total sample resided within regions. The coefficient of gene differentiation (Gst = 0.27) showed that the genetic variation within and among the 11 geographical regions was 73 and 27%, respectively. High value of mean number of alleles per locus was found in Iran (4.86) followed by Morocco (4.10) and Armenia (4.03). On the contrary, lower mean number of alleles per locus was detected in Yemen (2.83). The average gene diversity index across regions ranged from 0.52 (Slovakia) to 0.67 (Morocco) with an average of 0.60. Multivariate techniques of principal component analysis and clustering were employed to examine genetic relationship among the 73 emmer wheat accessions vis-a`-vis geographical regions of collections. The genetic distance coefficients for all possible 55 pairs of regional comparisons ranged from 0.63 (between Iran and Armenia, Georgia and Azerbaijan, Georgia and Slovakia) to 0.97 (between Morocco and Yemen, Spain and Georgia, and Turkey and Iran) with a mean of 0.82. From the PCA results, a two dimensional plot of PC1 versus PC2 was constructed. The scatter plot of the first two principal components which explained altogether 27% of the total variation depicted the presence of a clear pattern of geographical differentiation except in few cases like accessions from Caucasian region. Similar pattern of genetic relationships among accessions was observed in cluster analysis. The study provided genetic information of emmer wheat in relation to geographical regions of origin. The information could be utilized in crop improvement, germplasm conservation programs, and in further investigation.

Genetic diversity of Ethiopian emmer wheat Triticum dicoccum Schrank landraces using seed storage proteins markers

“…This result is to some extent in agreement with 73 emmer wheat accessions from Ethiopia highlands that have been recently studied with SSR markers (D=0.27) (Teklu et al, 2007). Therefore, low genetic differentiation between populations was observed due to migration or selection.…”

Agronomical, quality, and molecular characterization of twenty Italian emmer wheat (Triticum dicoccon) accessions

“…Previous studies conducted on emmer wheat focused either on agronomic traits (Laghetti et al 1998;D'Antuono 1989;Troccoli et al 1997Troccoli et al , 1998, quality aspects (Galterio et al 1994Strehlow and Hertzka Gand Weuffen 1994;Codianni et al 2000;Capocchi et al 2005), or molecular characterization (Barcaccia et al 2002;Large et al 2003;Pagnotta et al 2003aPagnotta et al , 2003bPagnotta et al , 2005Figliuolo and Perrino 2004;Teklu et al 2006). Our own previous studies focused on morphological and molecular characteristics on other emmer wheat accessions (Pagnotta et al 2005) or on agronomic and qualitative traits (De Vita et al 2006).…”

“…Moreover, in conjunction with agronomic and quality characteristics, the analysis of genetic variability represents a powerful tool for investigating germplasm resources. Recently, several kinds of molecular markers (RAPDs, RFLPs, ISSRs, and SSRs) have been utilized for monitoring and characterizing genetic variability in emmer wheat accessions (Barcaccia et al 2002;Large et al 2003;Pagnotta et al 2003aPagnotta et al , 2003bPagnotta et al , 2005Figliuolo and Perrino 2004;Teklu et al 2006). However, results obtained utilizing molecular markers occasionally produce patterns of genetic variation that are not adequately related to agronomic traits (Hodgkin et al 2001).…”

Cultivated emmer wheat (Triticum dicoccon Schrank), an old crop with promising future: a review

“…Al Khanjari et al (2007) analyzed genetic diversity in emmer wheat populations from Oman, using 29 SSR or microsatellite markers which could distinguish accessions from different origins (Dakhilia, Sharqia, Batinah and Dhofar districts). Genetic diversity was investigated by Teklu et al (2007) in 73 accessions of emmer wheat from 11 geographical regions using a set of 29 SSR markers. Diversity in this study was highest in materials from Iran, Morocco and Armenia, and lowest in Yemen and Slovakia.…”