RAPD Markers Linked to Induced Glaucousness in Bread Wheat

Abstract

Plants have various morphological and physiological characteristics that enable them to grow and reproduce in low-rainfall environments (Johnson et al. 1983). Glaucousness has been previously reported as an adaptive trait for drought tolerance in bread wheat (Johnson et al. 1983; Fischer and Wood, 1979), in durum wheat (Clarke et al., 1994), in barley (Baenziger et al., 1983), in oat (Bengtson, et al., 1978), and in sorghum (Jordan et al., 1983). An important function of leaf epicuticular waxes (glaucousness) is to increase the efficiency of stomatal control of water loss by reducing the cuticular conductance to water vapor (Jordan et al., 1984). This advantage of glaucousness may permit more efficient use of soil water in dryland situations, and supports the finding that the ratio of net carbon exchange to transpiration is higher for glaucous genotypes (Richards et al., 1986).
The inheritance of glaucousness in wheat has been studied on the conventional level (Al-Bakry, 2009). Chromosomes 2B, 2D, and 3A were found to bear three different glaucousness genes in wheat (Stuckey, 1972). These three genes
are responsible for the production of glaucousness of leaf, spike and peduncle.
Molecular biology techniques in plant include genetic identification or fingerprinting of molecular markers. The technique of analyzing molecular markers is based on the detection of the DNA sequences or combinations that are unique to the individual plant under study (Henry,
1997). Molecular markers are powerful tools that can be used for marker-assisted selection (Horvath et al., 1995) and as landmarks for map-based cloning of resistance genes (Michelmore, 1995; Bai et al., 1999; Liu et al., 2001). In wheat, RFLPs, AFLPs, SSRs, and RAPD markers have been used to study wheat resistance genes (Liu et al., 2001; Abdel-Tawab et al., 2003). Thus, molecular marker technology may provide new tools for the investigation of molecular markers linked to glaucousness in wheat.
RAPD have been proposed by several groups as efficient tools for identification of DNA markers associated with agronomically important traits (Banerjee et al., 1999). Linkage between a polymorphic marker and the target locus is confirmed and quantified by using the segre-
gating population from which the bulks were generated. Probes or primers for loci that are polymorphic and absolutely linked to the gene or region used to distinguish the individuals comprising the bulks will detect clear differences between the bulks. Bulked segregant analysis does not reveal novel types of variation but rather allows the rapid screening of many loci and therefore the identification of segregating markers in the target region (Michelmore et al., 1991).