Rapid classification of partial waxy wheats using PCR-based markers

Abstract

Mutations in the three homeologous waxy loci Wx-A1, Wx-B1, and Wx-D1 of a waxy wheat line have previously been characterized at the molecular level. Using combinations of these mutations, six types of partial waxy wheat plus wild type and waxy wheat (types 1–8) can be produced. Here, we describe primer sets for all three loci that can be used under a single set of conditions, allowing 32 lines to be characterized as types 1–8 in a single PCR run using a 96-well plate. Using multiplex PCR, mutations at the Wx-B1 and Wx-D1 loci can be identified in a single PCR, reducing the number of reactions necessary to identify and select the desired partial waxy wheat line. A single multiplex PCR can be used to detect all three mutations when products are analyzed using capillary electrophoresis on a microchip device. The PCR conditions and primers are effective with a number of cultivars from other countries, indicating that the mutations found at the Wx-A1 and Wx-B1 loci of these cultivars likely have the same origins as the mutations in the corresponding loci of the waxy wheat line used in this study. The PCR selection method described here is an easy and effective alternative to the commonly used SDS–PAGE methods for identification of null alleles.Key words: partial waxy wheat, amylose, PCR, capillary electrophoresis, marker-assisted selection.