GENETIC PURITY AND TESTING TECHNOLOGIES FOR SEED QUALITY - A COMPANY PERSPECTIVE

A high level of genetic purity in crop varieties must be achieved and maintained for agronomic performance as well as to encourage investmen t and innovation in plant breeding and to ensure that the improvements in productivity and quality imparted by breeders are delivered to the farmer and, ultimately, to the consumer. Traditionally, morphological comparisons have formed the basis for genetic purity evaluations. How ever, replicated field observations are time-consuming, expensive and unreliable. Morphology cannot provide information on the purity of spe cific genetic attributes that relate to grain quality or to pest or he rbicide resistance bred into varieties. Biochemical assays, including isozymes, can distinguish varieties within several species. Isozymes h ave been routinely used in checking seed-lot purity in maize (Zea mays L.) for the past 20 years. Newer DNA-based technologies such as restr iction fragment length polymorphisms and more recently developed metho ds that use the polymerase chain reaction can allow even more discrimi native and faster identification of varieties. However, none of the DN A methods have replaced biochemical methods for seed purity assays, ot her than in a relatively select group of crops with very high seed val ue, due to their high datapoint cost. It will require further miniatur ization, automation and enhanced capabilities to process numerous samp les simultaneously before newly developed methods supplant biochemical methods for routine usage in purity testing. New varieties that have major genes for herbicide or insect resistance incorporated within the m require purity assays during product development and following seed production of the commercial variety. Immunological or DNA sequence as says can be developed and automated systems are required to process hu ndreds of thousands of individuals. Ultra-high, micro-array technologi es and single-molecule detection systems are now under development. Th ese technologies offer the promise that adequate distinction and high sample throughput will be combined. New methods may eclipse the capabi lities of biochemical methodologies, thereby potentially raising genet ic purity standards and enabling farmers and consumers better to utili ze and benefit from increasingly productive Varieties that are bred fr om a more diverse base of genetic resources.