Lentils by Mohar Singh

Author:Mohar Singh
Language: eng
Format: epub
ISBN: 9780128135235
Publisher: Elsevier Ltd.
Published: 2018-08-09T16:00:00+00:00

Fig. 6.3 Basic procedure for marker-assisted selection.

6.3.1 Molecular Marker Identification, Linkage Map Development and QTL Mapping

For a molecular breeding program, the availability and easy accessibility of genomic resources is a prerequisite. Technological advances have provided a range of resources like molecular markers, genetic linkage maps, whole genome sequences, transcriptomes, etc. The very first types of markers reported and used in lentils were morphological and isozyme markers (Zamir and Ladizinsky, 1984; Tadmor et al., 1987; Muehlbauer et al., 1989; Vaillancourt and Slinkard, 1993). Afterward, the information of different bases in the DNA molecule like point mutations and indels (insertion, deletion), a mutation in the repeat sequences were utilized to develop DNA-based markers in lentil. DNA markers have the advantages of abundance and high polymorphism over morphological and isozyme markers (Paterson et al., 1991), which can be generated to saturate a linkage map. Using the fragment length variation, restriction fragment length polymorphism (RFLP) markers were developed and were the first to be used for the construction of linkage map in lentils (Havey and Muehlbauer, 1989). Subsequently, PCR-based DNA markers, such as randomly amplified polymorphic DNA (RAPD) markers, were developed and used for diversity analysis, phylogenetic analysis, and for the identification of a taxonomic relationship among the members of genus Lens (Sharma et al., 1996; Ford et al., 1997; Ferguson et al., 2000), for linkage map construction (Eujayl et al., 1997, 1998a; Rubeena et al., 2003), for gene tagging (Eujayl et al., 1998b, 1999; Ford et al., 1999; Tullu et al., 2003), and for determining pathogen population structure (Ford et al., 2000). Amplified fragment length polymorphism (AFLP) markers have also been utilized for construction of genetic maps (Eujayl et al., 1998a; Durán et al., 2004; Hamwieh et al., 2005; Kahraman et al., 2004), to analyze genetic diversity in lentils (Sharma et al., 1996; Závodná et al., 2000), and to identify markers linked to traits (Tullu et al., 2003).

With the advantage of SSRs over other markers, these markers have been developed in lentils also. However, only two reports had been published that were related to SSR development in lentils (Závodná et al., 2000; Hamwieh et al., 2005, 2009), and some of them have been utilized for map construction (Durán et al., 2004; Hamwieh et al., 2005). More recently, a set of 122 and 360 new genomic SSR markers were reported by Verma et al., 2014; Andeden et al., 2015, respectively. Further, a large repertoire of 501 Lens SSR was developed by Verma et al., 2015 using two microsatellite genomic libraries enriched for (GA/CT) and (GAA/CTT) motif. Besides the above-reported markers, another class of markers has also been developed in lentils, intersimple sequence repeat (ISSR) markers, which are amplified with SSR-anchored primers and resistance gene analogue (RGA) markers. This type of marker is designed using the conserved region of the resistance genes of plants and has been used in mapping (Durán et al., 2004; Rubeena et al., 2003).

These PCR-based markers are being rapidly replaced by SNPs. Recently, a more advanced marker technology has been employed in lentils by Sharpe et al.

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