Flower-infecting fungi have caused many economically important diseases in crop production.The fungal pathogen Ustilaginoidea virens infects developing rice florets,causing false smut disease,which leads to reduced gr...Flower-infecting fungi have caused many economically important diseases in crop production.The fungal pathogen Ustilaginoidea virens infects developing rice florets,causing false smut disease,which leads to reduced grain yield and quality,as well as contamination with mycotoxins that pose hazards to human health and food security.To ensure rice production,substantial efforts have been made to understand the interaction between rice and U.virens.In this review,we summarize the current understanding of rice resistance mechanisms to U.virens.We discuss the evaluation of false smut resistance,quantitative resistance loci,potential defense strategies of rice panicles,pathogen effector-driven identification of resistance-related genes,and engineering of false smut resistance.We conclude by proposing an integrated defense system that includes disease avoidance,immune response,metabolic adaptation,and the inhibition of susceptibility factors.Furthermore,we outline four critical stages of interaction between rice and U.virens that are essential for understanding and enhancing organ-specific rice resistance to false smut disease.展开更多
Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major dise...Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major disease in rice production. In vitro co-cultivation of U. virens strain with young rice panicles showed that U. virens enters inside of spikelets from the apex and then grows downward to infect floral organs. In response to U. virens infection, rice host exhibits elevated ROS accumulation and enhanced callose deposition. The secreted compounds of U. virens can suppress rice pollen germination. Examination of sectioning slides of freshly collected smut balls demonstrated that both pistil and stamens of rice flower are infected by U. virens, hyphae degraded the contents of the pollen cells, and also invaded the filaments. In addition, U. virens entered rice ovary through the thin-walled papillary cells of the stigma, then decomposed the integuments and infected the ovary. The invaded pathogen could not penetrate the epidermis and other layers of the ovary. Transverse section of the pedicel just below the smut balls showed that there were no fungal hyphae observed in the vascular bundles of the pedicel, implicating that U. virens is not a systemic flower-infecting fungus.展开更多
Rice false smut has become an increasingly serious disease in rice （Oryza sativa L.） production worldwide. The typical feature of this disease is that the fungal pathogen Ustilaginoidea virens （Uv） specifical y in...Rice false smut has become an increasingly serious disease in rice （Oryza sativa L.） production worldwide. The typical feature of this disease is that the fungal pathogen Ustilaginoidea virens （Uv） specifical y infects rice flower and forms false smut bal , the ustiloxin-containing bal-like fungal colony, of which the size is usual y several times larger than that of a mature rice seed. However, the underlying mechanisms of Uv-rice interac-tion are poorly understood. Here, we applied time-course microscopic and transcriptional approaches to investigate rice responses to Uv infection. The results demonstrated that the flower-opening process and expression of associated transcription factors, including ARF6 and ARF8, were inhibited in Uv-infected spikelets. The ovaries in infected spikelets were interrupted in fertilization and thus were unable to set seeds. However, a number of grain-fil ing-related genes, including seed storage protein genes, starch anabolism genes and endosperm-specific transcription factors （RISBZ1 and RPBF）, were highly transcribed as if the ovaries were fertilized. In addition, critical defense-related genes like NPR1 and PR1 were downregulated by;Uv infection. Our data imply that Uv may hijack host nutrient reservoir by activation of the grain-fil ing network because of growth and formation of false smut bal s.展开更多
基金supported by grants from the Sichuan Natural Science Foundation(2024NSFSC0335 and SCCXTD-2024-SD-4 to D.-Q.L.)the National Natural Science Foundation of China(32372490 and 32072503 to J.F.)。
文摘Flower-infecting fungi have caused many economically important diseases in crop production.The fungal pathogen Ustilaginoidea virens infects developing rice florets,causing false smut disease,which leads to reduced grain yield and quality,as well as contamination with mycotoxins that pose hazards to human health and food security.To ensure rice production,substantial efforts have been made to understand the interaction between rice and U.virens.In this review,we summarize the current understanding of rice resistance mechanisms to U.virens.We discuss the evaluation of false smut resistance,quantitative resistance loci,potential defense strategies of rice panicles,pathogen effector-driven identification of resistance-related genes,and engineering of false smut resistance.We conclude by proposing an integrated defense system that includes disease avoidance,immune response,metabolic adaptation,and the inhibition of susceptibility factors.Furthermore,we outline four critical stages of interaction between rice and U.virens that are essential for understanding and enhancing organ-specific rice resistance to false smut disease.
文摘Ustilaginoidea virens is a flower-infecting fungus that forms false smut balls in rice panicle. Rice false smut has long been considered a minor disease, but recently it occurred frequently and emerged as a major disease in rice production. In vitro co-cultivation of U. virens strain with young rice panicles showed that U. virens enters inside of spikelets from the apex and then grows downward to infect floral organs. In response to U. virens infection, rice host exhibits elevated ROS accumulation and enhanced callose deposition. The secreted compounds of U. virens can suppress rice pollen germination. Examination of sectioning slides of freshly collected smut balls demonstrated that both pistil and stamens of rice flower are infected by U. virens, hyphae degraded the contents of the pollen cells, and also invaded the filaments. In addition, U. virens entered rice ovary through the thin-walled papillary cells of the stigma, then decomposed the integuments and infected the ovary. The invaded pathogen could not penetrate the epidermis and other layers of the ovary. Transverse section of the pedicel just below the smut balls showed that there were no fungal hyphae observed in the vascular bundles of the pedicel, implicating that U. virens is not a systemic flower-infecting fungus.
基金supported by Sichuan Agricultural University start-up packages awarded to W.-M.W.and J.F.grants from the China Postdoctoral Science Foundation (2012M521679 to J.F.)grants from the Special Fund for Agro-Scientific Research in the Public Interest (200903039 to F.H.and W.-X.S.)
文摘Rice false smut has become an increasingly serious disease in rice （Oryza sativa L.） production worldwide. The typical feature of this disease is that the fungal pathogen Ustilaginoidea virens （Uv） specifical y infects rice flower and forms false smut bal , the ustiloxin-containing bal-like fungal colony, of which the size is usual y several times larger than that of a mature rice seed. However, the underlying mechanisms of Uv-rice interac-tion are poorly understood. Here, we applied time-course microscopic and transcriptional approaches to investigate rice responses to Uv infection. The results demonstrated that the flower-opening process and expression of associated transcription factors, including ARF6 and ARF8, were inhibited in Uv-infected spikelets. The ovaries in infected spikelets were interrupted in fertilization and thus were unable to set seeds. However, a number of grain-fil ing-related genes, including seed storage protein genes, starch anabolism genes and endosperm-specific transcription factors （RISBZ1 and RPBF）, were highly transcribed as if the ovaries were fertilized. In addition, critical defense-related genes like NPR1 and PR1 were downregulated by;Uv infection. Our data imply that Uv may hijack host nutrient reservoir by activation of the grain-fil ing network because of growth and formation of false smut bal s.
