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Recessive Mutation Identifies Auxin-Repressed Protein ARP1, Which Regulates Growth and Disease Resistance in Tobacco

July 2014 , Volume 27 , Number  7
Pages  638 - 654

Yanying Zhao,1 Cheng Li,1 Jun Ge,1 Manyu Xu,1 Qian Zhu,1 Tingquan Wu,1,2 An Guo,1,3 Junyi Xie,1 and Hansong Dong1

1State Ministry of Education Key Laboratory of Integrated Management of Crop Pathogens and Insect Pests, Nanjing Agricultural University, Nanjing 210095, China; 2Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China; 3Shijiao Agricultural Service Center, Jijiang Qu, Chongqing 401426, China

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Accepted 25 February 2014.

To study the molecular mechanism that underpins crosstalk between plant growth and disease resistance, we performed a mutant screening on tobacco and created a recessive mutation that caused the phenotype of growth enhancement and resistance impairment (geri1). In the geri1 mutant, growth enhancement accompanies promoted expression of growth-promoting genes, whereas repressed expression of defense response genes is consistent with impaired resistance to diseases caused by viral, bacterial, and oomycete pathogens. The geri1 allele identifies a single genetic locus hypothetically containing the tagged GERI1 gene. The isolated GERI1 gene was predicted to encode auxin-repressed protein ARP1, which was determined to be 13.5 kDa in size. The ARP1/GERI1 gene was further characterized as a repressor of plant growth and an activator of disease resistance based on genetic complementation, gene silencing, and overexpression analyses. ARP1/GERI1 resembles pathogen-associated molecular patterns and is required for them to repress plant growth and activate plant immunity responses. ARP1/GERI1 represses growth by inhibiting the expression of AUXIN RESPONSE FACTOR gene ARF8, and ARP1/GERI1 recruits the NPR1 gene, which is essential for the salicylic-acid-mediated defense, to coregulate disease resistance. In conclusion, ARP1/GERI1 is an integral regulator for crosstalk between growth and disease resistance in the plant.

© 2014 The American Phytopathological Society