Assessment of Genetic Diversity and Population Structure in a Global Reference Collection of 531 Accessions of Carthamus tinctorius L. (Safflower) Using AFLP Markers

Abstract

Carthamus tinctorius L. (safflower) is an important oilseed crop that is cultivated in several countries. The present study investigates the genetic diversity and population structure of 531 safflower accessions from 43 countries representing all safflower growing regions of the world. Diversity analysis was performed using ten informative EcoRI/ MseI amplified fragment length polymorphism primer pairs that were identified by screening 150 primer combinations. The selected primer pairs generated 381 fragments of which 157 were polymorphic among the analyzed accessions. The genetic diversity indices obtained for the entire collection (I= 0.4536, H=0.2955) indicated high levels of molecular variability. The distance-based, neighbor-joining method classified the accessions into six clusters with internal subgroupings that were in consonance with 19 clusters obtained using Bayesian model-based BAPS analysis. Clusters obtained through STRUCTURE analysis (at K=4) could not be correlated with their geographically diverse origins, while BAPS analysis (at K=19) revealed geographical delineation with low admixture levels among most of the studied accessions. Accessions from Far East and Egypt clustered in distinct groups, indicating conserved nature of their gene pools. The Near East and Iran-Afghanistan regions were collectively found to harbor maximum diversity in accordance with earlier reports. Accessions from the Indian subcontinent showed substantial diversity that was previously undetected. The American accessions showed low molecular variability in contrast to earlier studies. Genetic sub-structuring within gene pools and interrelationships between accessions belonging to different regional pools was also observed. To the best of our knowledge, this is the first comprehensive study of existing genetic variability in a large collection of safflower germplasm with a global distribution, which provides a more accurate representation of genetic structuring in the crop. This information will facilitate selection of elite genotypes for broadening the genetic base of various breeding programs in safflower.

Utilization of Molecular, Phenotypic, and Geographical Diversity to Develop Compact Composite Core Collection in the Oilseed Crop, Safflower (Carthamus tinctorius L.) through Maximization Strategy

“…The safflower germplasm used in the present study comprised of 531 accessions. The details of the accessions including their PI numbers, country of origin and regional pool along with the strategy used for their selection has been described by Kumar et al ( 2015 ).…”

“…Safflower is severely affected by several biotic and abiotic stresses and is characterized by low yield and spiny nature which have discouraged farmers from adopting its cultivation in several countries including India (Nimbkar, 2008 ). Moreover, the breeding lines and cultivars of safflower harbor low genetic diversity (Kumar et al, 2015 ), which restricts their utility in breeding programs. Therefore, an extensive characterization of the prevalent genetic and phenotypic diversity among the global germplasm of the crop is required to facilitate development of effective crop improvement strategies.…”

Genetic Diversity Analysis of Safflower (Carthamus tinctorius) Accessions from Different Geographic Origins using ISSR Markers

“…These markers are a convenient option for providing preliminary genotyping data for a species without the need for prior genomic DNA sequence information (Chen et al, 2014). This information makes selection of elite genotypes easy for safflower breeding programs (Kumar et al, 2015).…”

Development of Genomic Microsatellite Markers in Carthamus tinctorius L. (Safflower) Using Next Generation Sequencing and Assessment of Their Cross-Species Transferability and Utility for Diversity Analysis

“…A wide range of dominant markers such as random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) have been used for assessing the genetic diversity of safflower [ 16 – 20 ]. However, the dominant inheritance pattern of these markers does not allow detection of allelic information, which is important for crop breeding.…”