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Abstract Considering the indispensable significance and utilities of meta-substituted pyridines in medicinal, chemical as well as materials science, a direct meta-selective C–H functionalization of pyridines is of paramount importance, but such reactions remain limited and highly challenging. In general, established methods for meta C–H functionalization of pyridines rely on the utilization of tailored electrophilic reagents to realize the intrinsic polarity match. Herein, we report a complementary electrochemical methodology; diverse nucleophilic sulfinates allow meta-sulfonylation of pyridines through a redox-neutral dearomatization-rearomatization strategy by a tandem dearomative cycloaddition/hydrogen-evolution electrooxidative C–H sulfonation of the resulting oxazino-pyridines/acid-promoted rearomatization sequence. Besides, several salient features, including exclusive regiocontrol, remarkable substrate/functional group compatibility, scale-up potential, and facile late-stage modification, have been demonstrated, which further contributes to the practicality and adaptability of this approach.

Abstract Background NAC (NAM, ATAF and CUC) transcriptional factors constitute a large family with more than 150 members in rice and several members of this family have been demonstrated to play crucial roles in rice abiotic stress response. In the present study, we report the function of a novel stress-responsive NAC gene, ONAC066, in rice drought and oxidative stress tolerance. Results ONAC066 was localized in nuclei of cells when transiently expressed in Nicotiana benthamiana and is a transcription activator with the binding ability to NAC recognition sequence (NACRS) and AtJUB1 binding site (JBS). Expression of ONAC066 was significantly induced by PEG, NaCl, H2O2 and abscisic acid (ABA). Overexpression of ONAC066 in transgenic rice improved drought and oxidative stress tolerance and increased ABA sensitivity, accompanied with decreased rate of water loss, increased contents of proline and soluble sugars, decreased accumulation of reactive oxygen species (ROS) and upregulated expression of stress-related genes under drought stress condition. By contrast, RNAi-mediated suppression of ONAC066 attenuated drought and oxidative stress tolerance and decreased ABA sensitivity, accompanied with increased rate of water loss, decreased contents of proline and soluble sugars, elevated accumulation of ROS and downregulated expression of stress-related genes under drought stress condition. Furthermore, yeast one hybrid and chromatin immunoprecipitation-PCR analyses revealed that ONAC066 bound directly to a JBS-like cis-elements in OsDREB2A promoter and activated the transcription of OsDREB2A. Conclusion ONAC066 is a nucleus-localized transcription activator that can respond to multiple abiotic stress factors. Functional analyses using overexpression and RNAi-mediated suppression transgenic lines demonstrate that ONAC066 is a positive regulator of drought and oxidative stress tolerance in rice.

Abstract The NAC (NAM, ATAF and CUC) family is one of the largest plant-specific transcription factor (TF) families. Members of this family are implicated in plant growth, development and stress responses. Recent functional studies demonstrate that a number of NAC TFs function as positive or negative regulators of plant immunity to biotrophic, hemibiotrophic or necotrophic pathogens, as modulators of the hypersensitive responses and stomatal immunity or as virulence targets of pathogen effectors. They affect plant immunity through their regulatory impact on signaling of plant hormones, which in turn are key players in plant immune responses. This review summarizes current knowledge and recent progress in our understanding of the biological functions of NAC TFs in plant immunity and discusses perspectives and directions for further study to elucidate the molecular mechanisms of NAC TF functions in immunity and potential application in improvement of crop disease resistance.