Abstract
Rice sheath rot disease caused by Sarocladium oryzae (S. oryzae) infection is an emerging disease, and infection can cause yield losses of 20–85%. Adequate potassium (K) application is a feasible strategy for rice tolerance to S. oryzae infection. However, little is known about the metabolic mechanisms regulated by K that allow rice to cope better with S. oryzae infection. The present study performed a comparative metabolome and transcriptome analysis of rice with different K nutrition statuses before and upon S. oryzae infection. Sarocladium oryzae infection triggered a hydrogen peroxide (H2O2) burst, and K starvation aggravated the accumulation of H2O2 in the flag leaf sheath (FLS), which resulted in lipid peroxidation. Likewise, K deficiency altered the lipid homeostasis of the host plants by hyperaccumulation of 1-alkyl-2-acylglycerophosphoethanolamine. K starvation decreased the content of glycoglycerolipids including monogalactosyldiacyglycerol and digalactosyldoacylglycerol during S. oryzae infection, which destroyed the stability of bilayer membranes. In contrast, sufficient K supply increased antioxidant-related transcript expression (for example, the genes related to glutathione-S-transferase biosynthesis were upregulated), which activated the antioxidant systems. Additionally, upon S. oryzae infection, K starvation amplified the negative impacts of S. oryzae infection on flag leaf photosynthetic potential. These results provide new insight into the role of K in alleviating S. oryzae infection. Adequate K supply decreased the negative impacts of sheath rot disease on rice growth by alleviating lipid peroxidation and maintaining lipid homeostasis.
Highlights
Rice (Oryza sativa L.) is a widely grown crop worldwide, that plays an important role in food security
Low‐K Rice Leaf Sheaths are Hypersensitive to S. oryzae Infection The typical symptoms of Sheath rot (ShR) disease were observed in the flag leaf sheath (FLS) upon S. oryzae inoculation
Our results showed that the DGDG/MGDG ratio was significantly lower in K-starved rice (0.17) than in K-sufficient rice (0.31) during S. oryzae infection (Fig. 6b), which is in agreement with our hypothesis that K deficiency aggravates the degradation of the bilayer membrane during S. oryzae infection
Summary
Rice (Oryza sativa L.) is a widely grown crop worldwide, that plays an important role in food security. The tolerance capacity of host plants is often associated with cell-tissue metabolic processes, such as amino. Zhang et al Rice (2021) 14:81 acid and lipid metabolism, which directly take part in plant-pathogen interactions (Fagard et al 2014; Rojas et al 2014). An oxidative burst protects plants against pathogenic infection; the consistent accumulation of hydrogen peroxide (H2O2) induces lipid peroxidation, which, when it exceeds a certain threshold level, may contribute to membrane damage and cell death (Triantaphylidès et al 2008; Nita and Grzybowski 2016). The tolerance that plants usually display against infection by a fungal pathogen occurs by maintaining the stability of cellular membranes and regulating lipid homeostasis (Raffaele et al 2009). S. oryzae infection may induce oxidative stress, further resulting in cell death (Bigirimana et al 2015). Regulating the host plant’s metabolism to improve its tolerance ability is an important strategy against S. oryzae infection
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