Assessment of genetic diversity in Moroccan sesame (Sesamum indicum) using ISSR molecular markers

Abstract

There is a need for sesame (Sesamum indicum L.) breeding in Morocco to release performant and adapted varieties, which requires a large genetic variability in the germplasm to be used. In this context, genetic diversity of sesame populations from different locations in Tadla area was investigated using ISSR (Inter Sequence Simple Repeats) markers as a simple method to reveal polymorphism among them. A total of 130 individuals representing 31 populations were sampled. Twenty-four ISSR primers were used for analysis of individuals representing the 31 different sesame populations grown in different agroclimatic zones of Tadla, accounting for 90% of sesame cultivation area in Morocco. Indeed, seven primers showed legible and reproducible genomic profiles with an interesting number of bands. A total of 57 bands were obtained with ISSR primers, of which 47 were polymorphic. PIC (Polymorphic Information Content) ranged from 0.002 to 0.350, showing that ISSR markers are informative and relevant for discriminating the populations evaluated. The similarity coefficient of ISSR data ranged from 0.509 to 1, with an average of 0.870. The results obtained showed that Moroccan sesame populations are characterized by a low genetic diversity, suggesting a genetic proximity among them. Therefore, new germplasm should be either introduced from diverse geographical origins or created through mutagenesis breeding in order to broaden the existing genetic variability.

First Report of Sesame Mutants Tolerant to Severe Drought Stress during Germination and Early Seedling Growth Stages

“…The cultivars currently available in Morocco are genetically very close, as shown by recent studies based on phenotypical traits [23] and molecular markers [24]. Thus, a mutagenesis breeding program was launched to broaden the existing genetic variability, using the chemical mutagen ethyl methane sulfonate (EMS).…”

The Use of ISSR markers for clustering sesame genotypes based on geographical origin

“…The PIC of the marker with values ranging from 0 to 1 and locus having PIC values near to 1 are more desirable [22,23]. However, the PIC of the primers used in this study is higher than that reported a PIC of 0.169 using 7 ISSR primers [14].…”

“…The polymorphism information content (PIC) of the primers used ranged from 0.2109 (I2) to 0.3646 (T22), with an average of 0.2987. The PIC reveals the degree of the ability of the primer to differentiate the genotypes [14]. The PIC value of 0.2987 (almost 0.3) showed low to moderate ability of the primers to differentiate the Indonesian sesame collections.…”

“…ISSR involved using micro-satellite sequence order that spread across the genome as primers in a polymerase chain reaction to produce multi-locus markers [12,13]. Researchers reported studies of diversity in sesame over the world using ISSR [13,14]. ISSR markers could detect the level of genetic diversity and group sesame collections.…”

Moroccan sesame: Current situation, challenges, and recommended actions for its development

“…El Harfi et al (2021) reported that traditional Moroccan sesame populations are characterized by wild traits such as long cycle, low seed retention and lack of resistance/tolerance to abiotic and biotic stress. In addition, these populations are genetically very close, characterized by a low genetic diversity (El Harfi et al, 2021). Therefore, increasing sesame productivity can be achieved by, first, increasing the existing genetic variability and, then, developing high-yielding, drought-tolerant, pest and disease-resistant varieties adapted to Moroccan conditions.…”