title: Transcriptional and posttranscriptional regulation of the tomato leaf mould disease resistance gene Cf-9.
abstract: Plant disease resistance (R) genes confer effector-triggered immunity (ETI) to pathogens carrying complementary effector/avirulence (Avr) genes. They are traditionally recognized to function at translational and/or posttranslational levels. In this study, however, transcriptional and posttranscriptional regulation of Cf-9, a tomato R gene conferring resistance to leaf mould fungal pathogen carrying Avr9, was demonstrated. Expression of the Cf-9 gene was 10.8-54.7 folds higher in the Cf-9/Avr9 tomato lines than in the Cf-9 lines depending on the seedling age, indicating that the Cf-9 gene expression was strongly induced by Avr9. Moreover, expression of the Cf-9 gene in the 5-day-old Cf-9/Avr9 seedlings at 33 °C was approximately 80 folds lower than that at 25 °C, and was enhanced by 23.4 folds at only 4 h post temperature shift from 33 °C to 25 °C, demonstrating that the Avr9-mediated induction of the Cf-9 gene expression is reversibly repressed by high temperature. Expression of the Cf-9 gene in the Cf-9 seedlings was similarly affected by temperature as in the Cf-9/Avr9 seedlings, implying that the genetic control of temperature sensitivity of the Cf-9 gene expression is epistasis to its Avr9-mediated induction. Additionally, a miRNA sly-miR6022, TGGAAGGGAGAATATCCAGGA, targeting the leucine-rich repeat (LRR) domain spanning LRR13-LRR14 of the Cf-9 gene transcript was predicted. Over-expression of this miRNA resulted in over 88% reduction of the Cf-9 gene transcripts in both Nicotiana benthamiana and tomato, and thus verifying the function of sly-miR6022 in degrading the Cf-9 gene transcripts. Collectively, our results reveal that the tomato R gene Cf-9 is strongly regulated at transcriptional level by pathogen Avr9 in a temperature-sensitive manner and is also regulated at posttranscriptional level by a miRNA sly-miR6022.
authors.affiliation: Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University, 866 Yu Hang Tang Road, Hangzhou 310058, China. Electronic address: liwen547249317@126.com.
authors.forename: Wen
authors.initials: W
authors.lastname: Li
authors.affiliation: Center of Analysis and Measurement, Zhejiang University, 866 Yu Hang Tang Road, Hangzhou 310058, China. Electronic address: ypxu@zju.edu.cn.
authors.forename: You-Ping
authors.initials: YP
authors.lastname: Xu
authors.affiliation: Institute of Biotechnology, College of Agriculture and Biotechnology, Zhejiang University, 866 Yu Hang Tang Road, Hangzhou 310058, China. Electronic address: xzhcai@zju.edu.cn.
authors.forename: Xin-Zhong
authors.initials: XZ
authors.lastname: Cai
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D060467:Disease Resistance / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D018869:Heat-Shock Response / Q000502:physiology*; D006358:Hot Temperature; D018551:Solanum lycopersicum / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D015533:Transcriptional Activation / Q000502:physiology*
chemical_list: C109609:Cf protein, Lycopersicon esculentum; D005656:Fungal Proteins; D008562:Membrane Glycoproteins; D010940:Plant Proteins; C073605:AVR9 protein, Cladosporium fulvum
keywords: Avr9; Cf-9; Posttranscriptional regulation; Temperature sensitivity; Transcriptional regulation; miR6022