Molecular Plant Breeding 2016, Vol.7, No.10, 1-17
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for fertility restoration than morphological markers in several lines of cotton (Shanti et al., 2001); DNA markers
having high polymorphism in germplasm collections are desired in marker assisted selection (Bolek, 2003).
Marker assisted selection has advantage over conventional breeding, reviewed by many researchers (Collard and
Mackill, 2008; Kumpatla et al., 2012; Waqas et al., 2014). Plant breeders utilize DNA markers for selection of
desirable traits on molecular basis in spite of observing phenotypically (Helentjaris et al., 1986), furnishing the
basis for using the molecular assisted selection (Welsh and McClelland 1990; Vos et al.,1995; Struss and Plieske,
1998). Molecular markers are desired for improving traits in many essential crops; rice (Mackill et al., 1999),
wheat (Koebner and Summers, 2003), maize (Stuber et al., 1999; Tuberosa et al., 2003) and barley (Thomas, 2003;
Williams, 2003). Cotton is an important cash crop at global level and marker assisted selection has not got desired
goals due to compatible barriers through historic domestication and insufficient polymorphism (Iqbal et al., 2001;
Rahman et al., 2005; Abdurakhmonov et al., 2008).
Many economical traits such as yield, quality and some forms of disease resistance are controlled by many genes
and are known as quantitative traits (also ‘polygenic, or ‘complex’ traits). In order to increase the production;
awareness about the extent of heredity about economical traits on molecular basis has shifted plant breeders to
marker assisted selection (Bolek et al., 2005). DNA markers linked to the QTL of interest increase the efficiency
of breeding, decreasing costly and lengthy phenotypic selection (Collard et al., 2005). Transference of required
economic valuable characters from wild species to upland cotton having minimum linkage drag is accomplished
by marker assisted selection which is based on tracing of genomic regions in interspecific programs by molecular
markers and quantitative trait loci (Tanksley et al., 1989; Young and Tanksley, 1989; Abdurakhmonov et al.,
2011). Through the increased numbers of next generation sequencing, enormous markers can be analyzed across
the genomes which allows genome-wide studies (Schuster, 2011).
For genetic improvement with the objective of enhancing yield of field crops, it is necessary to learn about
molecular markers evolution and their utilization in crop improvement. The objective of this review is to describe
the utilization and evolution of molecular marker technologies and overview MAS activities in cotton.
3 DNA Makers in Cotton
DNA profiling in plants is principally used for observing genetic diversity, germplasm maintenance and
determining markers affiliated with required traits. Genetic conservation is based on grip about extent of genetic
diversity prevailing in the germplasm (Jubrael et al., 2005). Molecular markers are easy to evolve due to presence
of enormous genomic databases (Andersen and Lubberstedt, 2003) and they are highly useful for plant breeders as
these markers are source of isolation, maintenance, detection of heredity, marker assisted selection and genomic
profiling (Kalia., 2011). Mishra et al., (2014) suggested that the ideal DNA marker should be having the following
traits;
1. Highly polymorphic as it is compulsory for genetic studies,
2. Co-dominancewhichshows the differenceof homozygotes and heterozygotes of diploid organism,
3. Frequent occurrence in the genome,
4. Selective neutral behavior,
5. Cheap and fast assay,
6. Reproducible and easy exchange of data among laboratories.
The development of molecular markers is based on cost of identification of marker methodology, efficiency and
polymorphism (Bernardo, 2008). The classification of DNA markers into three classes is based on the method of
their detection: (1) hybridization-based; (2) polymerase chain reaction (PCR) based and (3) DNA sequence based
(Winter and Kahl, 1995).
4 Restriction Fragment Length Polymorphism (RFLP)
