Molecular markers in management of ex situ PGR – A case study.

Worldwide germplasm collections contain about 7.4 million accessions of plant genetic resources for food and agriculture. One of the 10 largest ex situ genebanks of our globe is located at the Leibniz Institute of Plant Genetics and Crop Plant Research in Gatersleben, Germany. Molecular tools have been used for various gene bank management practices including characterization and utilization of the germplasm. The results on genetic integrity of longterm- stored gene bank accessions of wheat (self-pollinating) and rye (open-pollinating) cereal crops revealed a high degree of identity for wheat. In contrast, the out-pollinating accessions of rye exhibited shifts in allele frequencies. The genetic diversity of wheat and barley germplasm collected at intervals of 40 to 50 years in comparable geographical regions showed qualitative rather than a quantitative change in diversity. The inter- and intraspecific variation of seed longevity was analysed and differences were detected. Genetic studies in barley, wheat and oilseed rape revealed numerous QTL, indicating the complex and quantitative nature of seed longevity. Some of the loci identified were in genomic regions that co-localize with genes determining agronomic traits such as spike architecture or biotic and abiotic stress response. Finally, a genome-wide association mapping analysis of a core collection of wheat for flowering time was performed using diversity array technology (DArT) markers. Maker trait associations were detected in genomic regions where major genes or QTL have been described earlier. In addition, new loci were also detected, providing opportunities to monitor genetic variation for crop improvement.

Monitoring the threat of unintentional transgene flow into maize gene banks and breeding materials

The use of transgenic crops is steadily increasing around the world, led by soybean (based on total area) and maize (in terms of total number of countries). Transgenic maize is grown in at least 17 countries across four continents: Africa, America, Asia and Europe. The comprehensive global spread of transgenic maize has significant implications for organizations involved in germplasm conservation and genetic enhancement; particularly as some countries require a GMO-free declaration when receiving shipments of maize germplasm. This article describes the protocol used by the International Maize and Wheat Improvement Center (CIMMYT) for monitoring unintentional transgene flow in maize genebank and breeding plots. The protocol is based on polymerase chain reaction (PCR) markers for detecting specific recombinant DNA sequences in bulked samples collected from sentinel plots. To date, no unintentional transgene flow has been detected in CIMMYT fields of maize genebank accessions or breeding materials.

In vitro regeneration and genetic fidelity of Tigridia pavonia (L. f.) DC

Plants of Tigridia pavonia (L.f.) DC were regenerated from twin-scaling explants cultured on Murashige and Skoog and N6 basal medium. The highest formation of shoots per responding explant was obtained on N6 medium supplemented with 4.5 uM 2,4-dichlorophenoxy acetic acid in combination with 2.2 uM benzylaminopurine. Shoots rooted readily on N6 basal medium supplemented with 1 g I-1 activated charcoal and 2.6 uM naphtalenacetic acid. The rooted shoots achieved 100 percent survival. Inter Simple Sequence Repeat analysis was carried out to check for possible genetic alterations in plants obtained after two consecutive subcultures. The results revealed that the recovered plants did not exhibit any type of polymorphism.