Molecular Markers And Their Application In Walnut Improvement

The capacity of molecular markers to permit the assignment of a sample to a particular individual, provenance, stand or species within an allowable livelihood of error has led to wide variety of practical applications. Breeders use markers to understand and monitor levels of genetic diversity and genetic differentiation in breeding population compared to wild relatives. When marker resolution and population genetic structure permit the identification of specific strands or provenances then breeders can potentially make use of untapped genetic diversity located there. The development of molecular markers has become an almost necessary complement to hardwood tree populations for superior growth, form and quality characteristics. Molecular markers are essentially important for determining the reproductive biology and population structure of natural plantations and identify genes affecting quantitative traits .Considerable efforts have been exerted over last forty years in conventional tree improvement programmes through breeding and selection and strategies for breeding and tree improvement of temperate hardwoods have been developed. The long generation and reproductive cycle are some of the problems imposed on conventional tree breeding programmes. Almost any kind of molecular marker can be used for fingerprinting walnut. The most widely used have been RFLPs, RAPDs, AFLPs, SSRs and ISSRs. In this paper we review the work carried out using different molecular marker approaches for improvement of walnut and analyze advantages and disadvantages of various methods.