ABSTRACT
In Arabidopsis thaliana (Arabidopsis), nonhost resistance (NHR) is influenced by both leaf age and the moment of inoculation. While the circadian clock and photoperiod have been linked to the time-dependent regulation of NHR in Arabidopsis, the mechanism underlying leaf age-dependent NHR remains unclear. In this study, we investigated leaf age-dependent NHR to Pyricularia oryzae in Arabidopsis. Our findings revealed that this NHR type is regulated by both miR156-dependent and miR156-independent pathways. To identify the key players, we utilized rice-FOX Arabidopsis lines and identified the rice HD-Zip I OsHOX6 gene. Notably, OsHOX6 expression confers robust NHR to P. oryzae and Colletotrichum nymphaeae in Arabidopsis, with its effect being contingent upon leaf age. Moreover, we explored the role of AtHB7 and AtHB12, the Arabidopsis closest homologues of OsHOX6, by studying mutants and overexpressors in Arabidopsis-C. higginsianum interaction. AtHB7 and AtHB12 were found to contribute to both penetration resistance and post-penetration resistance to C. higginsianum in a leaf age- and time-dependent manner. These findings highlight the involvement of HD-Zip I AtHB7 and AtHB12, well-known regulators of development and abiotic stress responses, in biotic stress responses in Arabidopsis.
Subject(s)
Arabidopsis Proteins , Arabidopsis , Arabidopsis/metabolism , Leucine Zippers , Arabidopsis Proteins/metabolism , DNA-Binding Proteins/metabolism , Plant Leaves/metabolism , Gene Expression Regulation, Plant , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolismABSTRACT
Nonhost resistance (NHR) is the most robust and durable resistance in plants, but its spatiotemporal regulation is poorly understood. The circadian clock functions in a tissue-specific manner and regulates individual physiological processes in plants. Using mutant and RNA-seq analyses, we revealed a role of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) in tissue-specific and time-of-day-specific regulation of NHR to Pyricularia oryzae (syn. Magnaporthe oryzae) in Arabidopsis thaliana (Arabidopsis). Targeted perturbation of CCA1 function in epidermis compromised time-of-day-specific regulation of NHR to P. oryzae in Arabidopsis. RNA-seq analysis showed that P. oryzae inoculation alters the transcriptome in penetration 2 (pen2) plants and identified POWDERY MILDEW RESISTANCE 5 (PMR5) as a candidate gene of direct targets of CCA1. Time-of-day-specific penetration resistance to P. oryzae was reduced in Arabidopsis pen2 pmr5 mutant plants. These findings suggest that epidermal CCA1 and PMR5 contribute to the establishment of time-of-day-specific NHR to P. oryzae in Arabidopsis.
Subject(s)
Arabidopsis Proteins , Arabidopsis , Circadian Clocks , Arabidopsis/metabolism , Circadian Clocks/genetics , Arabidopsis Proteins/metabolism , Gene Expression Regulation, Plant , Mutation , Epidermis/metabolism , Circadian Rhythm , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
A traceable linker that is potentially applicable to identification of a target protein of bioactive compounds was developed. It enabled not only thiol-induced cleavage of the linker for enrichment of the target protein but also selective labelling to pick out the target from contaminated non-target proteins for facile identification.
