eChapter Name: Role of DNA Technology in Seed Purity Testing
9789372197969
eBook Name: RECENT ADVANCES IN CROP VARIETY IDENTIFICATION USING DNA TECHNOLOGY
Introduction
As the seed market has become more globalized, seed trade has seen a rise in competitiveness as well as stricter quality requirements. Throughout the entire seed manufacturing process, thorough management is necessary to ensure high seed quality, from initial planning to final distribution. Among the various seed quality parameters, genetic purity is particularly critical in determining the authenticity and planting value of a seed lot. Genetic purity refers to the degree of purity within a seed lot, the genetic integrity of an F1 hybrid in a hybrid seed lot, or the difference between a submitted seed sample and the stated variety. During manufacturing, achieving complete (100%) varietal purity is challenging, even when recommended protocols are strictly followed. Outcrossing, partial off-type removal, and physical mixing during harvest, storage, or seed handling are a few examples of these factors can result in unintended varietal impurities (Bradford, 2006). Seed firms, producers, and suppliers conduct laboratory-based evaluations for internal quality control or post-control grow-out testing on seed lots to guarantee the necessary levels of purity. Assessments for genetically modified trait purity and the accidental inclusion of genetically modified (GM) seeds in non- GM seed lots are now necessary due to the introduction of transgenic varieties into the worldwide market, which has further broadened the scope of seed purity testing. Thus, seed purity testing is a cornerstone of agricultural production, ensuring that the seeds sown in the fields conform to their designated genetic identity. This process is essential for maintaining varietal integrity, meeting regulatory requirements, and ensuring high agricultural productivity (Sandra et al., 2023). The quality and genetic purity of seeds all directly impact crop productivity, pest and disease resistance, and overall farm profitability. Traditional seed purity assessment methods rely heavily on morphological, physiological, and biochemical traits. These methods include visual examination of seed characteristics, seedling grow-out tests, electrophoresis-based protein profiling, and chemical marker-based identification. However, these approaches often suffer from several limitations, such as the influence of environmental conditions on phenotypic traits, subjective assessments, and the need for significant time and labour. The accuracy and reproducibility of such conventional techniques can be further affected by variations in experimental conditions and the expertise of personnel conducting the tests.The advent of molecular biology has brought a paradigm shift in seed purity testing. DNA-based technologies provide precise, reliable, and high-throughput solutions that overcome the limitations of traditional methods. These molecular approaches allow for direct examination of genetic material, offering greater accuracy in varietal identification, hybrid seed purity assessment, and detection of genetic contamination. DNA markers can distinguish even closely related varieties, enabling seed companies, regulatory bodies, and farmers to ensure the authenticity of seed lots with high confidence. This chapter provides an overview of various DNA-based techniques employed in seed purity testing, including polymerase chain reaction (PCR)-based markers, single nucleotide polymorphism (SNP) markers, and high-throughput sequencing (HTS) technologies.