Transcript Rachel Melnick PhD student Department of Plant pathology

FIELD EVALUATION OF
ENDOPHYTES FOR MANAGEMENT
OF WITCHES’ BROOM ON CACAO
RACHEL MELNICK
ANISSA POLEATEWICH
DEPARTMENT OF PLANT PATHOLOGY
PENN STATE UNIVERSITY
Department
of Plant
Pathology
Previous work



INIAP station in Pichilingue Ecuador
Isolated endophytic bacteria from elite cacao
trees escaping disease
Screened isolates at Penn State to determine
which bacterial endophytes to study further
Growth chamber studies



Plants maintained
in growth chambers
Detached leaf
assays used to
screen isolates
Colonized leaves
challenged with
pathogen
Ecuador field trials


Selected 4 bacterial isolates based on
performance in growth chamber studies
Investigated foliar colonization of these bacteria
on 5 genotypes of cacao in the field
Susceptible (EE19 and IMC67)
 Tolerant (A2634 and A2126)
 High yielding and Resistant (CCN51)


Colonized foliage of small potted plants and
placed under larger trees in May 2007
Experimental System
Disease
Challenge
TIME
Bacterial
Application
Colonization
Ecuador field trials
Disease challenge in Ecuador
Susceptible tree
full of witches’
broom
Spores raining
from infected
trees onto
seedlings
Seedlings
undergoing
disease
screening
Preliminary observations


Endophytic colonization occurred on all
genotypes
Disease developed on seedlings
 Disease
ratings are being taken monthly
 Preliminary data has been analyzed and
published in PDMR

Bacteria were re-applied to plants in
November 2007, March 2008, and May 2008
Disease severity
One bacterial treatment has completely
suppressed disease....as of March 2008
100
AUDPC (Disease Severity)

80
60
40
20
0
Control
A2076
CCAT
EET
Bacterial Treatments
Cur3
Disease severity
Tolerant genotypes have significantly less
disease than susceptible genotypes
100
AUDPC (Disease Severity)

80
60
40
20
0
EET19
CCN51
A2634
Cacao genotype
A2126
IMC67
+C
ontr
ol
EET
19 +
A20
76
EET
19 +
C
CAT
EET
19 +
EET
103
ht
EET
19 +
CUR
CCN
3
51 +
Con
trol
CCN
51 +
A20
76
CCN
51 +
C
CAT
CCN
51+
EET
103
ht
CCN
51 +
CUR
3
A26
34 +
Con
trol
A26
34 +
A20
76
A26
34 +
C
C
A26
AT
34 +
EET
103
ht
A26
34 +
CUR
3
A21
26 +
Con
trol
A21
26 +
A20
76
A21
26 +
C
C
A21
AT
26 +
EET
103
ht
A21
26 +
CUR
IMC
3
67 +
Con
trol
IMC
67 +
A20
76
IMC
67 +
C
C
IMC
AT
67 +
EET
103
ht
IMC
67 +
CUR
3
EET
19
AUDPC (Disease Severity)
Coupling tolerant genotypes with
bacteria can reduce disease
200
150
100
50
0
Clone and Treatment Combinations
Future



Continuing INIAP trial…..Rachel is currently
in Ecuador collecting data
Replicating field trial on the Nestle farm in
Valencia, Los Rios, Ecuador
Inoculation of bacteria on established tree
branches
Future


Molecular analysis (ARISA) of microbial
populations to determine how application of
biocontrol agents impacts native microbes
Molecular analysis (qPCR) of leaves to
determine how endophytes affect plant
defense pathways
 Real
time PCR used to quantify mRNA to
determine the expression of genes in the plant
Related Projects



Management of postharvest disease on apple
Achieved 90% reduction in bitter rot severity
in preliminary tests  Adams county, PA
Experiment repeated in Bolivia
 Giovanna
Plata at PRO-IMPA
Acknowledgements
PSU Plant Path
Paul Backman
USDA-ARS SPCL
Bryan Bailey
Eric Rosenquist
INIAP
Carmen Suarez
Danilo Vera
Karina Solis
USDA-ARS SPCL
USDA-ARS International Programs
PSU CAS Tag- Along Program
PSU Plant Path. Travel Award
PSU Department of Plant Pathology
USAID
SANREM CRSP
IPM CRSP