Maize Chief System

A new high-throughput method for genetic purity testing of maize hybrid varieties is presented

The method is based on rapid homogenization of maize seed in a standard 96-wells microplate, followed by isoelectric focusing (horizontal IEF) of the crude homogenate and staining the gel for malate dehydrogenase (MDH) activity.

IEF of the crude homogenates is done using the ProTec MDH Gel Kit comprising highly reproducible rehydrated acrylamide gels ( gels with a thickness of 0,5 mm) Because there are washed before drying, they are free from monomeracrylamid and are non toxic. Gels are polymerized on support polyester films with 2 x 52 in-gel wells that enable quick and easy sample loading using a 12-channel multipipet.

A special IEF ampholyte (Sepalyte™) mixture to reach the proper pH gradient and MDH staining chemicals complete the kit. IEF of MDH from maize seed shows clear and easy to interpret expression of all five maize MDH genes. The phenotypic variability of MDH is governed by several alleles per MDH gene which gives rise to more than 1000 possible combinations of MDH bands.

The high genetic discriminative power of the MDH system makes it possible to develop a hybrid purity test based on a difference in the MDH pattern for the majority of maize hybrids.

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