Journal Article

Molecular mapping of the Pl sub(16) downy mildew resistance gene from HA-R4 to facilitate marker-assisted selection in sunflower

Liu, Zhao, Gulya, Thomas J, Seiler, Gerald J, Jan, Chao-Chien, Vick, Brady A

2012

Overview

The major genes controlling sunflower downy mildew resistance have been designated as Pl genes. Ten of the more than 20 Pl genes reported have been mapped. In this study, we report the molecular mapping of gene Pl sub(16) in a sunflower downy mildew differential line, HA-R4. It was mapped on the lower end of linkage group (LG) 1 of the sunflower reference map, with 12 markers covering a distance of 78.9 cM. One dominant simple sequence repeat (SSR) marker, ORS1008, co-segregated with Pl sub(16), and another co-dominant expressed sequence tag (EST)-SSR marker, HT636, was located 0.3 cM proximal to the Pl sub(16) gene. The HT636 marker was also closely linked to the Pl sub(13) gene in another sunflower differential line, HA-R5. Thus the Pl sub(16) and Pl sub(13) genes were mapped to a similar position on LG 1 that is different from the previously reported Pl sub(14) gene. When the co-segregating and tightly linked markers for the Pl sub(16) gene were applied to other germplasms or hybrids, a unique band pattern for the ORS1008 marker was detected in HA-R4 and HA-R5 and their F sub(1) hybrids. This is the first report to provide two tightly linked markers for both the Pl sub(16) and Pl sub(13) genes, which will facilitate marker-assisted selection in sunflower resistance breeding, and provide a basis for the cloning of these genes.

• Subject: Helianthus