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N ATIO N A L
TA I WA N
UNIVERSITY
2014光合作用與植物生理研討會
Phalaenopsis efficiently acclimate to highlight
environment through orchid mycorrhization
菌根化有助於蝴蝶蘭適應高光環境
Ming-Chih Lee (李明治), Doris C.N. Chang (張喜寧), Chun-Wei
Wu (吳俊偉), Ying-Tung Wang (王寅東) and Yu-Sen Chang (張育
森)*
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Background
 Phalaenopsis:
1. Epiphytic
2. CAM metabolism
3. Establish a symbiotic
relationship with fungi
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 Light intensity:
1. Saturating PPF: 130-180 μmol∙m-2∙s-1 (Lee
and Guo, 2012)
2. Photoinhibition: >200 μmol∙m-2∙s-1 PPF (Baker,
2008)
3. Commercial cultivation: 280-380 μmol∙m-2∙s-1
(Chen and Wang, 1996).
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 How plants cope with highlight ?
1. Photoacclimation
2. Photoprotection
3. Photorepair
(Ragni et al., 2008)
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 Photoacclimation:
Plant modulates and optimizes its
photosynthetic performance according to the
light environment.
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Photoprotection:
Plant prevents or minimizes light energy from
inducing photodamage.
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Photorepair :
Plant degrades and de novo synthesizes the
damaged D1 protein.
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Hypothesis
Orchid mycorrhization
Photosynthetic
Performance
? ?
? ? ?
? ?
Highlight growing
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Objectives
To evaluate the OM effects on the growth
of HL-Phalaenopsis, and to elucidate the
photochemical mechanisms involved in
photoacclimation to photoinhibitory
irradiance.
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Materials & Methods
 Plant materials:
1. Five-month-old Phalaenopsis amabilis
‘KC1410’ were cultivated in 12-cm diameter
pots filled with the processed bark of Pinus
radiata for 6 months.
2. 20N-8.7P-16.6K Peters solution at 0.5 g∙L-1
was provided once every two weeks.
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Greenhouse conditions:
1. 230-870 μmol∙m-2∙s-1 (due to cloudiness)
about 40% of the prevailing solar radiation.
2. Air temperature was controlled at 28/22°C
(day/night) by a pad and fan cooling system .
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Orchid mycorrhization:
1. Ceratobasidium sp. (AG-A, binucleates)
inoculum were prepared using peat and
potato-dextro solution.
2. 7 plants in a treatment, and totally 2
experimental repeats were conducted in this
study.
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Measurements:
1. Open flow gas exchange system (LI-6400)
2. Multi-Channel Chlorophyll Fluorometer
(MONI-PAM)
3. Spectrometer HandySpec Field
(tec5)
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LI-6400:
CO2 uptake rate was measured from 10 p.m. to
12 a.m..
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MONI-PAM:
1. 1st acropetal fully expanded leaf.
2. The fluorescence measurements
(Fv/Fm, ETR, ФPSII, qP, and the NPQ) were
made on the 30 min dark-adapted plants during
Phase III of CAM photosynthesis (2 p.m.) using
rapid light curve (RLC).
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tec5:
1. Assess growth quality and
photosynthesis using equations:
(1) NDVI computed as (R800 – R600) /
(R800 + R600) (Rouse et al., 1974)
(2) PRI computed as (R531 – R570) /
(R531 + R570) (Peñuelas et al., 1995).
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Results
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OM plants have longer leaves that result in greater
leaf span under highlight environment
Figure 1. Phalaenopsis amabilis ‘KC1410’ plants grown under
highlight environment with (OM) and without Ceratobasidium
sp. (NM) inoculation. Scale bar represents 10 cm.
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Table 1. Mycorrhizal effects on the growth characteristics, biomass, and
dry matter
partitioning enhances
of Phalaenopsis
plantlets
highlight
OM
colonization
plant
sizegrown
andunder
biomass
of
for 6 months. NM: non-mycorrhizal control; OM: orchid mycorrhizal
HL-Phalaenopsis
treatment; FW: fresh weight;
DW: dry weight. Water content: (FW −
DW)/FW.
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OM leaves achieve higher rate of CO2 uptake than the
NM plants at the night time
Figure 2. Carbon dioxide (CO2) uptake rate measured in the late
evening (10 p.m.) 6months after highlight cultivation of non-mycorrhizal
(NM) and mycorrhizal (OM) orchids (Phalaenopsis amabilis
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‘KC1410’).***p ≤ 0.001.
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OM plants have higher photoacclimation capabilities
than NM plants under HL environments
Figure 3. The maximum quantum yield of PSII photochemistry (Fv/Fm)
measured with PAM fluorometer on dark-adapted samples of
mycorrhizal (OM) and non-mycorrhizal (NM) Phalaenopsis during light21
recovery experiment.
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Higher ФPSII sustained during photoinhibition
demonstrates an higher carbon assimilation efficiency
in OM
plants
Figure 4. Analysis of light
dependent
changes in PSII operating
efficiency (ФPSII) in an intact leaf of Phalaenopsis amabilis ‘KC1410’
with (OM) or without (NM) mycorrhization grown under highlight
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environment.
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Figure 5. Analysis of light dependent changes in electron transport rate
(ETR) in an intact leaf of Phalaenopsis amabilis ‘KC1410’ with (OM) or
without (NM) mycorrhization grown under highlight environment.
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The sustained lower NPQ and higher qP indicate the
efficient photoprotection capability and radiation use
efficiency in OM plants.
Figure 6. Analysis of light dependent changes in photochemical
quenching (qP) and non-photochemical quenching (NPQ) in an intact
leaf of Phalaenopsis amabilis ‘KC1410’ with (OM) or without (NM)
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mycorrhization grown under highlight environment.
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Higher PRI represents higher photoprotection and
photosynthetic performance in OM plants.
Figure 7. Assessing photoprotection capacity with evaluation of
photochemical reflectance index (PRI) in an intact leaf of Phalaenopsis
amabilis ‘KC1410’ with (OM) or without (NM) mycorrhization grown
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under highlight environment.
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Conclusions
The improved photosynthetic
performance & radiation use efficiency in
PSII are probably the acclimation
mechanism of OM plants to efficiently
respond to highlight.
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Conclusions
The OM-mediated higher photosynthetic
performance & radiation use efficiency is
most evident around 800~1000 μmol∙m2∙s-1
PPF, which is close to the irradiance
during cultivation, thus indicates
photoacclimation.
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Conclusions
Excessive Light
Orchid
Mycorrhization
Photoinhibition
ФPSII, ETR,
qP, NPQ, PRI
Growth
Photoacclimation
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Members of YSC Laboratory
Department of Horticulture & Landscape Architecture
Yu-Sen Chang
Professor
E-mail: [email protected]
Tel: (02)33664858 # 206
Fax: (02)33664855
Ming-Chih Lee
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Ph.D student
E-mail: [email protected]
Tel: (02)33664858 # 302
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Thank you for your attention !
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