Potential use of selected antagonistic bacteria to control foot rot disease of black pepper (Piper nigrum L.) in Sarawak, Malaysia
Black pepper (Piper nigrum L.) is one of high value export crops in Malaysia and this crop can easily been destroyedby pests and diseases. One of the most important diseases is foot rot disease which iscaused by Phytophthora capsici. Foot rot disease isthe most dangerous disease in black pepper a...
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| Format: | Thesis |
| Language: | English |
| Published: |
2014
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/78141/1/FSPM%202014%205%20ir.pdf |
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| Summary: | Black pepper (Piper nigrum L.) is one of high value export crops in Malaysia and
this crop can easily been destroyedby pests and diseases. One of the most important
diseases is foot rot disease which iscaused by Phytophthora capsici. Foot rot disease
isthe most dangerous disease in black pepper and it is now become a major obstacle
to the black pepper industry in Malaysia. Thus, the objectives of this study wereto
survey the occurrence and distribution of foot rot disease in four major cultivation
areas which are Sibu, Sarikei, Kapit and Bintulu in Sarawak, Malaysia. Secondly to
isolate, identify and characterize P. capsici based on morphological and molecular
methods. Lastly, to investigate the potential use of indigenous endophytic bacteria to
control P. capsici under glasshouse condition. To achieve the first objective 13
survey areas in four major cultivating areas have been determined and conducted in
between November 2010 to January 2011. Survey activity was conducted based on
standard plant disease survey method. In study two, the causal pathogen and
endophytic bacteria were isolated using standard isolation method. These isolates
were then verified and characterized based on morphological and molecular
characteristics. Finally, glasshouse study was conducted to assess the efficacy of
potential endophytic bacteria to control P. capsici. Based on field survey data,
infected plants normally exhibited symptoms of yellowingof leaves, leaves
defoliationand wilting. High disease incidence and disease severity were recorded in
all surveyed sites. The mean percentage for disease incidence anddisease severity
were46.31 and 40.91%, respectively. P. capsici was successfully isolated using
baiting method using rose bengal agar (RBA) and selective media, P5ARPH.The
morphological characteristics of P. capsici were globose oogonia with paragynous
antheridia, chlamydospore, torulose hyphae, and lemon shape of sporangia with long
pedicels. In colony morphology, P. capsici showed very thick mycelia and formed
multiple like a rosewhen growthon PDA media. Pathogenicity test wasfurther
confirmed that the isolated fungus was pathogenic to black pepper plants. It was then
further confirmed by nested-PCR using specific primer pairs of PC-1/PC-2.
Antagonistic bacteria wassuccessfully isolated and screened. The potential of
biocontrol agents were found to be able to induce systemic resistance in plants as well as showing biological control traits like producing antibiotic compounds which
caused lysis to the phytopathogen cells. The use of antagonistic microorganisms
should be preferable method because the biological control agents are internal
colonizers and therefore more efficient to compete in the vascular systems. Thus,
this will certainly deprive P. capsici in terms of nutrientsuptake and space for their
proliferation. The three potential isolates known as BPA011, BPA040 and BPA025
were tested in-vitro showed high percentage of inhibition of radial growth (PIRG)
which were81.40, 82.97 and 80.83%, respectively. These isolates were successfully
identified using GC-FAME as Burkholderia cepacia, B. cenocepacia and Bacillus
alchalapilus, respectively. Based on their colonization, establishment and
localization ability in black pepper roots, B. cepacia and B. cenocepacia were
selected for efficacy study in the glasshouse against Phytopthora foot rot in black
pepper. Results revealed that they were able to suppress the growth of P. capsici
compared to the control treatment. Besides delaying disease onset, they are also
promoting the growth of the black pepper plant. Our study showed that disease
incidence was significantly lower at 90 days after inoculation with B. cenocepacia
(12.5%) and B. cepacia (18.75%). As expected positive control treatment presented
the highest value of disease incidence (81.25%) at 90 days after inoculation. This
indicated that B. cepacia and B. cenocepacia has a potential in controlling
Phytophthora foot rot disease. |
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