Plant variety and cultivar identification: advances and prospects

Abstract

Plant variety and cultivar identification is one of the most important aspects in agricultural systems. The large number of varieties or landraces among crop plants has made it difficult to identify and characterize varieties solely on the basis of morphological characters because they are non stable and originate due to environmental and climatic conditions, and therefore phenotypic plasticity is an outcome of adaptation. To mitigate this, scientists have developed and employed molecular markers, statistical tests and software to identify and characterize the required plant cultivars or varieties for cultivation, breeding programs as well as for cultivar-right-protection. The establishment of genome and transcriptome sequencing projects for many crops has led to generation of a huge wealth of sequence information that could find much use in identification of plants and their varieties. We review the current status of plant variety and cultivar identification, where an attempt has been made to describe the different strategies available for plant identification. We have found that despite the availability of methods and suitable markers for a wide range of crops, there is dearth of simple ways of making both morphological descriptors and molecular markers easy, referable and practical to use although there are ongoing attempts at making this possible. Certain limitations present a number of challenges for the development and utilization of modern scientific methods in variety or cultivar identification in many important crops.

Genetic diversity and relationships among different tomato varieties revealed by EST-SSR markers

“…In contrast, molecular markers such as restriction fragment length polymorphism, random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism, and simplesequence repeats (SSR) can provide an effective tool for variety identification since they are independent of environmental variation (Korir et al, 2013). Among the different available marker systems, SSR markers have become an important marker system for variety identification because of their genetic co-dominance, high reproducibility, and multiallelic variation (Powell et al, 1996), in addition to relative abundance and good genome coverage.…”

“…By June 2012, there were over 18,208 SSR markers deposited in the Sol Genomics Network (http//:www.solgenomics.net) and available for public use. In addition, many more are found in other databases and laboratories worldwide (Korir et al, 2013). The generation and characterization of EST-derived microsatellites from the tomato and crossspecies amplification in its closely related species and varieties by SSR markers have been done with a total of 7599 SSR markers being generated by in silico data mining of 83,785 sequences (Shirasawa et al, 2010).…”

A novel and efficient strategy for practical identification of tomato (Solanum lycopersicon) varieties using modified RAPD fingerprints

“…The presence of homonyms or synonyms within existing tomato varieties being sold in the markets shows the need to properly identify wild and cultivated tomato varieties and cultivars for conservation and use of these germplasm resources as well as in plant variety protection. The ability to distinguish varieties could be greatly enhanced by using appropriate molecular markers (Patil et al, 2010;Ezekiel et al, 2011;Korir et al, 2012). The well-documented advantages of optimized RAPD markers make it the technique of choice for the initial phase of this study.…”

“…The use of molecular markers serves as a modern and suitable approach to cultivar and variety identification, since it is more rapid and cost-effective (Korir et al, 2012). Different molecular marker techniques have been used in plant population genetics and identification, phylogenetic and biodiversity studies, analysis of recombination frequencies between genotypes, identification of genes for important agricultural traits and marker-assisted selection (Vishwanath et al, 2010;Sonah et al, 2011).…”

“…There are more than 7500 tomato varieties successfully bred and grown for various purposes worldwide, and plant variety registration bodies in different countries keep records of most of these varieties. Although each tomato variety has unique characters of interest to breeders and other researchers as well as growers, cases of synonyms and homonyms abound in the tomato industry just like in other crops, and this is an important problem that should not be overlooked but rather should be addressed (Korir et al, 2012). With the evolution of the tomato industry, the development and adoption of new varieties have gained popularity, thus making the breeding of and research on tomato varieties more and more important.…”