van den Burg Harrold A, Tsitsigiannis Dimitrios I, Rowland Owen, Lo Jane, Rallapalli Ghanasyam, Maclean Daniel, Takken Frank L W, Jones Jonathan D G
Sainsbury Laboratory, John Ines Centre, Norwich NR4 7UH, United Kingdom.
Plant Cell. 2008 Mar;20(3):697-719. doi: 10.1105/tpc.107.056978. Epub 2008 Mar 28.
Virus-induced gene silencing identified the Avr9/Cf-9 RAPIDLY ELICITED gene ACRE189 as essential for the Cf-9- and Cf-4-mediated hypersensitive response (HR) in Nicotiana benthamiana. We report a role for ACRE189 in disease resistance in tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum). ACRE189 (herein renamed Avr9/Cf-9-INDUCED F-BOX1 [ACIF1]) encodes an F-box protein with a Leu-rich-repeat domain. ACIF1 is widely conserved and is closely related to F-box proteins regulating plant hormone signaling. Silencing of tobacco ACIF1 suppressed the HR triggered by various elicitors (Avr9, Avr4, AvrPto, Inf1, and the P50 helicase of Tobacco mosaic virus [TMV]). ACIF1 is recruited to SCF complexes (a class of ubiquitin E3 ligases), and the expression of ACIF1 F-box mutants in tobacco compromises the HR similarly to ACIF1 silencing. ACIF1 affects N gene-mediated responses to TMV infection, including lesion formation and salicylic acid accumulation. Loss of ACIF1 function also reduced confluent cell death induced by Pseudomonas syringae pv tabaci. ACIF1 silencing in Cf9 tomato attenuated the Cf-9-dependent HR but not Cf-9 resistance to Cladosporium fulvum. Resistance conferred by the Cf-9 homolog Cf-9B, however, was compromised in ACIF1-silenced tomato. Analysis of public expression profiling data suggests that Arabidopsis thaliana homologs of ACIF1 (VFBs) regulate defense responses via methyl jasmonate- and abscisic acid-responsive genes. Together, these findings support a role of ACIF1/VFBs in plant defense responses.
病毒诱导的基因沉默表明，Avr9/Cf-9快速诱导基因ACRE189对于本氏烟草中Cf-9和Cf-4介导的超敏反应（HR）至关重要。我们报道了ACRE189在番茄（番茄）和烟草（烟草）抗病性中的作用。ACRE189（在此重新命名为Avr9/Cf-9诱导的F-Box1 [ACIF1]）编码一种具有富含亮氨酸重复结构域的F-Box蛋白。ACIF1广泛保守，与调节植物激素信号的F-Box蛋白密切相关。烟草ACIF1的沉默抑制了由各种激发子（Avr9、Avr4、AvrPto、Inf1和烟草花叶病毒[TMV]的P50解旋酶）触发的HR。ACIF1被招募到SCF复合物（一类泛素E3连接酶）中，并且ACIF1 F-Box突变体在烟草中的表达与ACIF1沉默类似地损害了HR。ACIF1影响N基因介导的对TMV感染的反应，包括病斑形成和水杨酸积累。ACIF1功能的丧失也减少了丁香假单胞菌pv烟草诱导的融合细胞死亡。Cf9番茄中ACIF1的沉默减弱了Cf-9依赖性HR，但没有减弱Cf-9对番茄叶霉病的抗性。然而，Cf-9同源物Cf-9B赋予的抗性在ACIF1沉默的番茄中受到损害。对公共表达谱数据的分析表明，ACIF1（VFBs）的拟南芥同源物通过茉莉酸甲酯和脱落酸反应基因调节防御反应。总之，这些发现支持了ACIF1/VFBs在植物防御反应中的作用。
