Host-induced gene silencing of Phakopsora pachyrhizi genes in soybean mediated by the bean pod mottle virus
D. HU (1), Z. Chen (1) (1) Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, U.S.A.

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi, was first reported in Japan in 1902, and has spread to Africa, South America and North America. Currently, all U.S. commercial soybean cultivars are susceptible to P. pachyrhizi and the available management is fungicide application. However, fungicide application is not a long-term measure due to fungicide tolerance, environmental pollution, and increased production costs. Host induced gene silencing (HIGS) is an RNAi-based approach in which small interfering RNAs (siRNAs) of pathogen are produced in the host plant to specifically silence their targets in the invading pathogen. In a preliminary study, a 751-nt dsRNA of P. pachyrhizi acetyl-CoA acetyltransferase (ACT) was synthesized and co-inoculated with P. pachyrhizi urediniospores for 12hrs in vitro, which significantly reduced rust accumulation on detached leaves, demonstrating dsRNA can be taken up by the fungus. In order to determine whether HIGS can be used to protect soybean from P. pachyrhizi infection, 14 up-regulated genes in the germinating P. pachyrhizi urediniospores were cloned into a bean pod mottle virus (BPMV) based vector system and introduced into soybean by bombardment. Soybean plants expressing these dsRNA of selected genes were inoculated with P. pachyrhizi urediniospores. Among them, the rust accumulation on soybean plants expressing ACT reduced by 60%. These studies demonstrated that HIGS could be an effective strategy to control ASR.

Abstract Number: P9-260
Session Type: Poster