Combining R gene and quantitative resistance increases effectiveness of cultivar resistance against Leptosphaeria maculans in Brassica napus in different environments

• DOI: 10.1371/journal.pone.0197752
• Publication Date: 2018-05-23T17:38:57Z
• Authors: Yong-Ju Huang; Georgia K. Mitrousia; Siti Nordahliawat...; Aiming Qi; Bruce D. L. Fitt
• Keywords: Leptosphaeria maculans; Canker; Blackleg; Brassica rapa; Phoma

Using cultivar resistance against pathogens is one of the most economical and environmentally friendly methods for control crop diseases. However, can be easily rendered ineffective due to changes in pathogen populations or environments. To test hypothesis that combining R gene-mediated quantitative (QR) provide more effective than use either type on its own, effectiveness eight oilseed rape (Brassica napus) cultivars with different genes and/or QR Leptosphaeria maculans (phoma stem canker) was investigated 13 environments/sites over three growing seasons (2010/2011, 2011/2012 2012/2013). Cultivar Drakkar no used as susceptible sampling L. populations. Isolates were obtained from sites 2010/2011 assess frequencies avirulent alleles effector (AvrLm1, AvrLm4 AvrLm7) corresponding (Rlm1, Rlm4 Rlm7) field experiments. Results experiments showed DK Cabernet (Rlm1 + QR) Adriana (Rlm4 had significantly less severe phoma canker Capitol (Rlm1) Bilbao (Rlm4), respectively. controlled environment confirmed presence Rlm these four cultivars. Analysis mean AvrLm1 (10%) (41%) AvrLm7 (100%), suggesting Rlm1 resistances partially while Rlm7 still effective. Excel (Rlm7 Roxet (Rlm7), but difference between them not significant influence gene Rlm7. For two only QR, Es-Astrid NK Grandia (QR). relationship severity weather data among increased associated rainfall during leaf spot development stage temperature stage. Further analysis response environmental factors both an (e.g. Cabernet, Excel) sensitive a change Capitol, Bilbao) Grandia). These results suggest effective, stable