Frequency and distribution of the brown rust resistance gene B ru 1 and implications for the L ouisiana sugarcane breeding programme

• Published in: Plant breeding 2014-10, Vol.133 (5), p.654-659
• Main Authors: Parco, Arnold S., Avellaneda, Mavir C., Hale, Anna H., Hoy, Jeffrey W., Kimbeng, Collins A., Pontif, Michael J., Gravois, Kenneth A., Baisakh, Niranjan
• Format: Article
• Language: English
• ISSN: 0179-9541; 1439-0523
• DOI: 10.1111/pbr.12186

Brown rust, caused by the fungus P uccinia melanocephala , poses an increasing threat to sugarcane industries worldwide. Recently, markers R 12 H 16 and 9020‐ F 4 were developed for a major resistance gene B ru 1 that contributes to a significant proportion of brown rust resistance in multiple sugarcane industries. Marker‐assisted screening of L ouisiana sugarcane germplasm showed a low frequency (4.3%, five out of 117 clones) of B ru 1 among sugarcane cultivars and elite breeding clones. Likewise, among progeny of crosses involving wild/exotic germplasm, only 14 of 208 clones (6.7%) tested B ru 1 positive. However, B ru 1 frequency was higher (28.7%, 52 of 181 clones) in wild/exotic germplasm, which indicated that diverse genetic resources are available for B ru 1 introgression. Commercial B ru 1‐positive cultivar, ‘ L 01‐299', was resistant to brown rust. However, B ru 1‐positive cultivar, ‘ L 10‐146’, was susceptible while B ru 1‐negative cultivars, such as ‘ L 99‐233’, showed resistance to brown rust. B ru 1‐negative clones with brown rust resistance offer an opportunity to identify alternate sources of resistance, which can be pyramided with B ru 1 for effective and durable resistance in sugarcane against the changing pathogen.