New tools for characterizing early brown stem rot disease resistance signaling in soybean

Abstract

Brown stem rot (BSR) reduces soybean [Glycine max (L.) Merr.] yield by up to 38%. The BSR causal agent is Phialophora gregata f. sp. sojae, a slow-growing, necrotrophic fungus whose life cycle includes latent and pathogenic phases, each lasting several weeks. Brown stem rot foliar symptoms are often misdiagnosed as other soybean diseases or nutrient stress, making BSR resistance especially difficult to phenotype. To shed light on the genes and networks contributing to P. gregata resistance, we conducted RNA sequencing (RNA-seq) of a resistant genotype (PI 437970, Rbs3). Leaf, stem, and root tissues were collected 12, 24, and 36 h after stab inoculation with P. gregata, or mock infection, in the plant stem. By using multiple tissues and time points, we could see that leaves, stems, and roots use the same defense pathways. Our analyses suggest that P. gregata induces a biphasic defense response, with pathogen-associated molecular pattern (PAMP) triggered immunity observed in leaves at 12 and 24 h after infection (HAI) and effector triggered immunity detected at 36 h after infection in the stems. Gene networks associated with defense, photosynthesis, nutrient homeostasis, DNA replication, and growth are the hallmarks of resistance to P. gregata. While P. gregata is a slow-growing pathogen, our results demonstrate that pathogen recognition occurs hours after infection. By exploiting the genes and networks described here, we will be able to develop novel diagnostic tools to facilitate breeding and screening for BSR resistance.

Deep learning-based phenotyping for genome wide association studies of sudden death syndrome in soybean

“…Glyma.13g256500 has been previously reported as a candidate gene for resistance to Phytophthora sojae (Li et al, 2016). While, Glyma.13g257100, was found to have a negative effect on the susceptibility to soybean mosaic virus when silenced (Liu and Whitham, 2013;McCabe and Graham, 2020). Both genes have been previously identified in association with disease resistance, and Glyma.13g256500 was specifically found to have resistance to a soil-borne fungal pathogen, similar to SDS.…”

Molecular Breeding to Overcome Biotic Stresses in Soybean: Update

“…This disease is generally diagnosed as nutrient deficiency. To overcome misidentification of BSR, recently, McCabe and Graham [ 155 ] proposed a diagnostic approach based on genes and their network for fast and accurate identification. This approach may be helpful in management of this disease.…”

“…Further, the resistance was mapped to intervals ranging from 0.34 to 0.04 Mb, inclusive of BARCSOYSSR_16_1114 and BARCSOYSSR_16_1115 on chromosome 16. On the basis of these findings, it was concluded that only one gene is responsible for BSR resistance in soybean [ 155 ].…”

Gene Expression Responses to Sequential Nutrient Deficiency Stresses in Soybean

“…The annotations of the 21 DEGs in Figure 2 cluster L9 are associated with receptor like proteins (RLPs), leucine rich repeats (LRRs), and metal transport (Supplemental File 1: Table S1). This profile is noteworthy since in Arabidopsis, RLPs and LRRs regulate development, are known to confer resistance to a number of biological pathogens, and have been implicated in a number of abiotic stress tolerances [61][62][63]. Altered developmental regulation and defense responses are two hallmarks of the iron deficiency stress response in soybean.…”