Salicylic Acid and Systemic Acquired Resistance Play a Role in Attenuating Crown Gall Disease Caused...
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Salicylic Acid and Systemic Acquired Resistance Play a Role in Attenuating Crown Gall Disease Caused by Agrobacterium tumefaciens. Ajith Anand, Srinivasa Rao Uppalapati, Choong-Min Ryu2, Stacy N. Allen, Li Kang, Yuhong Tang, and Kirankumar S. Mysore* Plant Physiology, February 2008, Vol. 146, pp.703–715 Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
Salicylic Acid and Systemic Acquired Resistance Play a Role in Attenuating Crown Gall Disease Caused by Agrobacterium tumefaciens. Ajith Anand, Srinivasa
Salicylic Acid and Systemic Acquired Resistance Play a Role in
Attenuating Crown Gall Disease Caused by Agrobacterium tumefaciens.
Ajith Anand, Srinivasa Rao Uppalapati, Choong-Min Ryu2, Stacy N.
Allen, Li Kang, Yuhong Tang, and Kirankumar S. Mysore* Plant
Physiology, February 2008, Vol. 146, pp.703715 Plant Biology
Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma
73401
Slide 2
What's your idea ?
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the role of SA-mediated plant defense responses against
Agrobacterium the direct effects of SA on microbes SA Inhibits
Agrobacterium Growth in Vitro and Affects virulence SA Application
on Plants Transgenic Plants Expressing NahG Silencing of SA
Biosynthetic and Signaling Genes
. Zhu Y et al. Plant Physiol. 2003;132:494-505 2003 by American
Society of Plant Biologists
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If SA Application on Plants Decreases Agrobacterium Infection
exogenously applying SA to N. benthamiana through soil drenching
Leaves from the SA-treated and mock-treated plants were collected 7
d posttreatment and subjected to: stable and transient
transformation assays
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T-DNA Binary system
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The GUS reporter system (GUS: beta-glucuronidase) is a reporter
gene systembeta-glucuronidasereporter gene The purpose of this
technique is to analyze the activity of a promoter (in terms of
expression of a gene under that promoter)promoterexpression The
technique is based on beta-glucuronidase,beta-glucuronidase this
enzyme, can transform some specific colorless or non-fluorescent
substrates, into coloured or fluorescent
products.substratescoloured fluorescent Histochemical
spectrophotometrical fluorimetrical
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? N.benthamiana GV2260 (carrying the binary vector pBISN1)
stained with X-Gluc staining SA-treated fluorimetrical Incubate on
CIM Transient and stable transformation Leaf disck
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Quantification of transient transformation in the SA-treated
plants a significant reduction in GUS activity The inoculated
leaves were stained with X-Gluc staining solution The direct
effects of SA on Agrobacterium-mediated plant transformation
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GUS activity was measured in GV2260- infected leaf discs at 2,
5, and 10 dpi by recording the fluorescence of
4-methylumbelliferone a significant reduction in GUS activity
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the free SA using a mass spectrometry system SA treatment of N.
benthamiana plants result in increased SA levels.
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We therefore conclude that SA application partially block sA
grobacterium-mediated planttransformation. SA Application on Plants
Decreases Agrobacterium Infection
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Transgenic Plants Expressing NahG Are they Hyper susceptible to
Agrobacterium Infection? transgenic plants expressing
salicylatehydroxylase (NahG), which degrades SA to catechol.
Detached leaves of wild-type tomato plants (Moneymaker)and
NahG-overexpressing plants were vacuum infiltrated with the
disarmed strain A. tumefaciens GV2260 (carrying the binary vector
pBISN1) at a low concentration (1 3 105 cfu). Three days
postinfection the leaves were stained with X-Gluc for detecting GUS
expression. wild-type tomato plants NahG-overexpressing plants
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These results suggest that SA plays a role in protecting plants
against Agrobacterium infection.
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If SA Inhibits Agrobacterium Growth in Vitro and Affects Its
Virulence? the direct role of SA on bacterial growth and and
virulence SA may be an important determinant of Agrobacterium
pathogenicity
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However, SA at low concentrations (515 mM) did not affect the
growth of the bacteria in the rich media Agrobacterium growth
inhibition was observed when SA was supplemented in the minimal
media SA was added into the culture media at physiologically
relevant concentrations was monitored in both the minimal and rich
media If SA Inhibits Agrobacterium Growth in Vitro?
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Effect of SA on Agrobacterium growth in different media and
various concentrations of SA (0-15 m).
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if SA directly affects Agrobacterium virulence? leaf disc
infection assays with A. tumefaciens A348 treated with SA.
Agrobacterium attenuates its capacity to incite tumors on leaf
discs exogenous application of SA reduce the virulence of
Agrobacterium.
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If Agrobacterium Treated with SA Is Defective in Attaching to
Plant Cells? Agrobacterium attachment assay with the disarmed
strain A. tumefaciens KAt153 (carrying the binary vector pDSKGFPuv)
that was mock or SA treated (left panel: GFP fluorescence; right
panel: epifluorescence image). SA at 100 mM affected Agrobacterium
attachment SA may affect the virulence by interfering with the
attachment of Agrobacterium to plant cells.
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If SA Affects Agrobacterium Gene Expression? custom-made whole-
genome Affymetrix microarrays SA treatment significantly affected
the expression of the Ti plasmid genes 36 of the 37 genes were
induced by AS at 4 h and 103 of the 172 genes were induced by AS at
24 h, respectively
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SA repressed the expression of the bacterial virulence (vir
genes), the conjugal transfer (tra genes), and plasmid replication
genes (repABC operon), Using real-time quantitative reverse
transcription- PCR (qRT-PCR), we confirmed the differential
expression of few selected genes these results suggest that SA has
multiple effects on Agrobacterium resulting in reduced
virulence.
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Silencing of SA Biosynthetic and Signaling Genes in N.
benthamiana Increases Susceptibility to Crown Gall Disease
relatively larger tumors on the shoots of ICS-, NPR1-,and
SABP2-silenced plants compared with the tumors on Tobacco rattle
virus (TRV)TGFP- inoculated and wild typ plants
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Plant cell Virus-Induced Gene Silencing (VIGS) RdRp- Dicer RISC
AAAAAA RISC RNA induced silencing complex Tobacco Rattle Virus
(TRV) used as the VIGS vector
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These results indicate that SA biosynthetic and signaling genes
also play a significant role in antagonizing Agrobacterium
infection..
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BTH-Induced SAR Impairs Agrobacterium Infectivity In planta
tumor assay smaller tumors were observed on shoots of BTH- treated
N. benthamiana and tomato plants
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BTH-Induced SAR Impairs Agrobacterium Infectivity Stable
transformation assays Tumors produced on leaf discs derived from
both silenced and wild- type plants were smaller in BTH treated
plants
Slide 28
BTH-Induced SAR Impairs Agrobacterium Infectivity transient
transformation Leaves treated with BTH showed a significant
reduction in GUS activity at 2 and 5 dpi in both silenced and
wild-type plants
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both SA and SA-mediated plant defenses play a key role in
determinin Agrobacterium infectivity on plants independent of SA,
SAR is an important determinant in Agrobacterium infectivity both
endogenous SA levels and SAR are critical determinants of
Agrobacterium pathogenicity in plants
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Besides triggering the defense responses, SA had direct effects
on Agrobacterium fitness and virulence and therefore plays a
central role in Agrobacterium-plant interactions. we speculate that
SA competes with AS for direct or indirect interaction with
VirA
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exogenous application of SA or its analogs before the onset of
crown gall disease presents a possible means for achieving durable
disease control.