Frequency and distribution of the brown rust resistance gene Bru1 and implications for the Louisiana sugarcane breeding programme |
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| Authors: | Arnold S Parco Mavir C Avellaneda Anna H Hale Jeffrey W Hoy Collins A Kimbeng Michael J Pontif Kenneth A Gravois Niranjan Baisakh |
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| Institution: | 1. School of Plant, Environmental and Soil Sciences, Louisiana State University Agricultural Center, , Baton Rouge, LA, 70803 USA;2. Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, , Baton Rouge, LA, 70803 USA;3. Sugarcane Research Unit, USDA‐ARS, , Houma, LA, 70360 USA;4. Sugar Research Station, Louisiana State University Agricultural Center, , St. Gabriel, LA, 770067 USA |
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| Abstract: | Brown rust, caused by the fungus Puccinia melanocephala, poses an increasing threat to sugarcane industries worldwide. Recently, markers R12H16 and 9020‐F4 were developed for a major resistance gene Bru1 that contributes to a significant proportion of brown rust resistance in multiple sugarcane industries. Marker‐assisted screening of Louisiana sugarcane germplasm showed a low frequency (4.3%, five out of 117 clones) of Bru1 among sugarcane cultivars and elite breeding clones. Likewise, among progeny of crosses involving wild/exotic germplasm, only 14 of 208 clones (6.7%) tested Bru1 positive. However, Bru1 frequency was higher (28.7%, 52 of 181 clones) in wild/exotic germplasm, which indicated that diverse genetic resources are available for Bru1 introgression. Commercial Bru1‐positive cultivar, ‘L 01‐299', was resistant to brown rust. However, Bru1‐positive cultivar, ‘L 10‐146’, was susceptible while Bru1‐negative cultivars, such as ‘L 99‐233’, showed resistance to brown rust. Bru1‐negative clones with brown rust resistance offer an opportunity to identify alternate sources of resistance, which can be pyramided with Bru1 for effective and durable resistance in sugarcane against the changing pathogen. |
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| Keywords: | brown rust Bru1 Louisiana marker sugarcane |
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