Genome-Wide Associations and Transcriptional Profiling Reveal ROS Regulation as One Underlying Mechanism of Sheath Blight Resistance in Rice

Abstract

Rice sheath blight, caused by the necrotrophic fungus Rhizoctonia solani Kühn, continues to be an important and challenging rice disease worldwide. Here, we used genome-wide association studies over a high-density rice array to facilitate the identification of potential novel genes and quantitative trait loci related to sheath blight resistance. We identified multiple regions that significantly associated with independent disease components in chromosomes 1, 4, and 11 under controlled condition. In particular, we investigated qLN1128, a quantitative trait locus enriched with defense-related genes that reduce disease lesions in a near-isogenic line. RNA profiling of the line carrying qLN1128 showed a number of differentially expressed genes related to the reactive oxygen species (ROS)-redox pathway. Histochemical staining revealed less ROS accumulation on the resistant line, suggesting efficient ROS deregulation that delays pathogen colonization. The detection of genomic regions controlling multiple mechanisms of resistance to sheath blight will provide tools to design effective breeding interventions in rice.

Strategies to Manage Rice Sheath Blight: Lessons from Interactions between Rice and Rhizoctonia solani

“…Interestingly, the rice resistant line exhibits a significant less ROS accumulation compared with the susceptible line at 48 h post inoculation of R. solani (Oreiro et al 2020). In this case, pathogen attack may stimulate excessive ROS accumulation in the susceptible plants and thereby inducing cell death, which is conducive to the growth and colonization of necrotrophic fungi (Heller and Tudzynski 2011).…”

“…In this case, pathogen attack may stimulate excessive ROS accumulation in the susceptible plants and thereby inducing cell death, which is conducive to the growth and colonization of necrotrophic fungi (Heller and Tudzynski 2011). Therefore, ROS might function as a signal for R. solani to switch from the establishment to the necrotrophic stage (Noctor et al 2018;Oreiro et al 2020). Besides, exogenous and endogenous ROS has a promoting effect on the formation and development of R. solani sclerotia, while trehalose, a ROS-scavenger, functions as an inhibitor to sclerotial development, suggesting that trehalose might serve as a new antioxidant fungicide to inhibit sclerotial differentiation in R. solani AG-1 IA .…”

“…To effectively balance the role of ROS during the interaction between rice and R. solani, many smart strategies have evolved to regulate the ROS level to reduce damage and activate defense in rice. A quantitative trait locus qLN11 28 enriched in defense-related genes is involved in the activation of the genes related to the ROSredox pathway and alleviates ROS accumulation in rice cells, and thus delaying R. solani colonization (Oreiro et al 2020). The catalase OsCATC and chloroplast glutathione peroxidase involving in scavenging ROS are found in hub gene network in rice and might play an important role in maintaining normal ROS level in rice after R. solani infection (Alam and Ghosh 2018).…”

Functions of pipecolic acid on induced resistance against Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000 in tomato plants

“…The mechanisms of altered disease resistance often include the regulation of ROS accumulation (Mengiste et al, 2003). Usually, a greater accumulation of ROS is beneficial for pathogen infection (Kou, Qiu, & Tao, 2019; Oreiro et al., 2020; Singh et al., 2018). In the present study, lower ROS accumulation was detected in leaves from the seedlings pretreated with the Pip after pathogen inoculation compared with that of the control (Figures 3a and 5a).…”

Identification of rice (Oryza sativa L.) genes involved in sheath blight resistance via a genome‐wide association study

“…Rice plants are more susceptible to R. solani at the seedling, tillering and booting stages under high humidity and temperature conditions (Molla et al 2020;Oreiro et al 2019). These stages are considered key for R. solani infection because they directly affect rice yield.…”