Mutations in the N-terminal coding region of the harpin protein Hpa1 from Xanthomonas oryzae cause loss of hypersensitive reaction induction in tobacco

Wang, Xiaoyu; Song, Congfeng; Miao, Weiguo; Ji, Zhao-Lin; Wang, Xiben; Yan, Zhang; Zhang, Jia-huan; Hu, John; Borth, Wayne B.; Wang, Jinsheng

doi:10.1007/s00253-008-1651-7

Cited by 32 publications

(56 citation statements)

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“…Given that the α-helix motif present in the N-terminal region of Hpa1 on its bioactivities [5, 14, 24, 25], we assumed that the motif is likely to serve as a determinant of the translocator function. This hypothesis was validated by fragment deletions toward the Hpa1 sequence (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Hpa1 is a type III translocator in Xanthomonas oryzae pv. oryzae

Wang

Zhang

et al. 2018

BMC Microbiol

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BackgroundPathogenic Gram-negative bacteria interact with their eukaryotic hosts by deploying the type III translocon to inject effector proteins into the cytosol of eukaryotic cells. The translocon compositions, the number and biochemical characteristics of type III translocators in animal-pathogenic bacteria have been well elucidated, but information is lacking for plant-pathogenic bacteria. With extensive studies on biological functions of the Hpa1 protein secreted by the type III secretion system in Xanthomonas oryzae pv. oryzae (Xoo), we show here that Hpa1 is a type III translocator based on measurements of two proteins categorized as transcription activator-like (TAL) effector.ResultsHpa1 was functionally associated with the TAL effector PthXo1 or AvrXa10 by genetic analysis of the wild-type Xoo strain and related mutants or recombinant strains. Inoculation experiments suggested that Hpa1 is required not only for the virulent role of PthXo1 in the susceptible rice variety Nipponbare, but also for the avirulent function of AvrXa10 on the resistant rice variety IRBB10. Hpa1 is unrelated to the secretion of PthXo1 and AvrXa10 out of bacterial cells. However, Hpa1 is critical for both TAL effectors to be translocated from bacterial cells into the cytosol of rice cells based on replicate experiments performed on the susceptible and resistant varieties, respectively. Hpa1-mediated translocation of PthXo1 is coincident with induced expression of rice SWEET11 gene, which is the regulatory target of PthXo1, resulting in the occurrence of the bacterial blight disease in the susceptible rice variety. By contrast, the immune hypersensitive response is induced in agreement with induced expression of rice Xa10 gene, which is the target of AvrXa10, only when AvrXa10 is translocated from bacteria into cells of the resistant rice variety. All the virulent or avirulent performances of the TAL effectors are nullified by directed mutation that removes the α-helix motif from the Hpa1 sequence.ConclusionsThe genetic and biochemical data demonstrate that Hap1 is a type III translocator at least for TAL effectors PthXo1 and AvrXa10. The effect of the directed mutation suggests that Hpa1 depends on its α-helical motif to fulfil the translocator function.Electronic supplementary materialThe online version of this article (10.1186/s12866-018-1251-3) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

“…While the N-terminal α-helix governs Hpa1 oligomerization [23], the first 53 residues determine its bioactivities in plants [5, 14, 24, 25]. Hpa1 affects virulence of the Xoo strain PXO99 in susceptible japonica rice variety Nipponbare [5] while the virulence is provided by the TAL effector PthXo1 [26].…”

Section: Introductionmentioning

confidence: 99%

Hpa1 is a type III translocator in Xanthomonas oryzae pv. oryzae

Wang

Zhang

et al. 2018

BMC Microbiol

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“…Like all harpin orthologs identified in different species of Gram-negative plant pathogenic bacteria (Wei et al 1992; He et al 1993; Dong et al 1999, 2004, 2005; Kim and Beer 2000; Liu et al 2006, 2010, 2011), Hpa1 induces plant growth and defense responses (Peng et al 2004; Liu et al 2006; Ren et al 2006a, b, 2008; Wu et al 2007; Zhang et al 2007, 2011a, b; Chen et al 2008a, b; Sang et al 2012). The dual effect depends on plant sensing of the nitroxyl-terminal region in the Hpa1 sequence (Wang et al 2008; Li et al 2014b; Ji et al 2015). From this region, the 10–42 residue fragment (Hpa1 10–42 ) has been isolated, produced by prokaryotic expression (Wu et al 2007; Chen et al 2008a; Li et al 2014b), and analyzed for its multifaceted effects on Arabidopsis (biological model plant), tobacco (cash crop), tea (drinking crop), rice (food crop), and wheat (food crop).…”

Section: Introductionmentioning

confidence: 99%

Harpin Hpa1 promotes flower development in Impatiens and Parochetus plants

Dong

Zhang

2016

Bot Stud

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BackgroundThe harpin protein Hpa1 has multiple beneficial effects in plants, promoting plant growth and development, increasing crop yield, and inducing plant resistance to pathogens and insect pests. In these effects, the 10–40 residue fragment (Hpa110–42) isolated from the Hpa1 sequence is 1.3 to 7.5-fold more effective than the full length.ResultsThis study extends the beneficial effects of Hpa1 and Hpa110–42 to flower development in three species of the garden balsam Impatiens and the garden scoparius Parochetus communis plant. The external application of Hpa1 or Hpa110–42 to the four ornamental plants had three effects, i.e., promoting flower growth, retarding senescence of fully expanded flowers, and increasing anthocyanin concentrations in those flowers and therefore improving their ornamental visages. Based on quantitative comparisons, Hpa110–42 was at least 17 and 42 % more effective than Hpa1 to increase anthocyanin concentrations and to promote the growth of flowers or delay their senescence.ConclusionOur results suggest that Hpa1 and especially Hpa110–42 have a great potential of horticultural application to increase ornamental merits of the different garden plants.

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“…Zhang et al , 2007, 2011; Chen et al , 2008 a , b ; Sang et al , 2012). The dual effect depends on plant sensing of the N-terminal region in the Hpa1 sequence (Wang et al , 2008; Li et al , 2013 a ). From this region, the 10–42 residue fragment (Hpa1 10–42 ) was isolated, produced by prokaryotic expression (Wu et al , 2007; Chen et al , 2008 a ; Li et al , 2013 a ), and analysed for its effects on Arabidopsis (biological model plant), tobacco (cash crop), tea (drinking crop), and rice (food crop).…”

Section: Introductionmentioning

confidence: 99%