Molecular Genetic Maps (Low/Moderate Density), Cereals, Legumes, Oil seeds, Vegetables, Trees, Mapping populations

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Your Ad Here	Molecular Genetic Maps (Low/Moderate Density) During the last two decades (1980-200) and in the early years of the 21st century, molecular genetic maps became available for all major crop and tree species (cereals, legumes, oil seeds, vegetables, trees, etc.). The mapping populations that were used for the construction of these maps included F2, BC1, RIL and DH populations, and the molecular markers that have been used for this purpose mainly included RFLP, RAPD, SSR and AFLP, although other marker systems like STS, ISSR and DAF were also utilized (for molecular markers).
For constructing a mapping population, when sufficient variability was not available within the germplasm of the crop, a wild species had to be crossed with a cultivar to provide for the diversity, which is a key to the success of constructing a map. For instance, in case of tomato, a wild species, Lycopersicon hirsutum or L. pennellii was often used; in case of barley, Hordeum spontaneum (wild barley) was used, and in case of bread wheat, a synthetic wheat (W7984) involving Aegilops tauschii, the D genome progenitor, was used for crosses leading to the construction of one of more mapping populations. In sugarcane, Saccharum spontaneum,the wild relative of sugarcane was used either directly for the preparation of a molecular map or for crosses with cultivated species S. officinarumfor generating a mapping population.
In each of the majority of crops used for molecular mapping, more than one molecular maps are often available. This is because, either separate maps were prepared using different marker systems, or more than one laboratories prepared independent maps, utilizing the same marker system, thus multiplying the number of maps for the same crop. This multiplicity of maps was sometimes necessary, because often in a single population, only a fraction of available markers segregated, so that several populations were needed to map all the available markers.
In some crops, eventually useful integrated maps were also prepared, utilizing the information from all the available maps. Some details about the available maps are presented in, where it can be seen that most of these maps are low to moderate density maps with variable resolution, suggesting that in many cases these maps still need to be saturated The present status of these molecular maps (at the beginning of the present century) in different crops will be briefly discussed in this section. For any details, readers should use the internet, where more detailed information about most of these maps is readily available