Resistance response of soybean genotypes to Asian Soybean Rust under controlled temperature conditions

CAMBURSANO MARIANA VIRGINIA; CAIRO CARLOS ALBERTO; BIANCHI JULIETA SOFIA; GOMEZ RODRIGO LIONEL; QUIJANO ÁLVARO

Rosario

Congreso; RAFV; 2023

Sociedad Argentina de Fisiología Vegetal

The temperature increase (T) due to climate change has significant implications for crops, and is likely to be partially associated with more severe diseases. Asian Soybean Rust (ASR), caused by the fungal Phakopsora pachyrhyzi (Pp), is a highly destructive disease with phytosanitary risks for soybean in Argentina. Even though ASR resistance genes has been identified, their effectiveness depends on the Pp isolates. In addition, the effect of T on the resistance responses remains poorly understood. Accurate characterization of disease traits under controlled environmental conditions is critical for germplasm selection in plant breeding programs. We studied the effect of different temperatures on soybean-Pp pathosystem using resistant and susceptible genotypes exposed to the BP08 Pp isolate under controlled environmental conditions. Resistance traits as Number of Uredinia per Lesion (N°UL), Percentage of Open Uredinia (%OU) and Sporulation Level (SL) were evaluated in 30 lesions of 12 soybean genotypes grown in contrasting mean temperatures (21.6°C and 26.6°C, for low-T and high-T, respectively). Two plants per genotype were inoculated at the 2nd and 3rd fully expanded trifoliate leaves by spraying 2.7 x 105 spores/mL of the BP08 Pp isolate. The phenotypic characterization was done 14 days post-inoculation, and means were compared by t-test. Higher temperature increased SL, N°UL and %OU in a 46, 36 and 32%, respectively (p≤0.10). Significant differences were also found in the resistance traits evaluated in many of the genotypes analyzed (p≤0.10). These preliminary findings suggest that an increase in temperature due to climate change could lead to an increase in ASR severity determining the importance of considering this effect in the manage of the soybean rust caused by Pp.