Cool-night temperature induces spike emergence and affects photosynthetic efficiency and metabolizable carbohydrate and organic acid pools in Phalaenopsis aphrodite.
After being acclimated to constant warm (28 degrees C day/28 degrees C night) and cool-night temperature (28 degrees C day/20 degrees C night) regimes in growth chambers for 2 weeks, the two groups of mature Phalaenopsis aphrodite subsp. formosana plants both clearly exhibited a diurnal oscillation of stomatal conductance, net CO(2) uptake rate, malate and starch levels, and the phosphoenolpyruvate carboxylase (EC 4.1.1.31) and NAD(+)-malic enzyme (EC 1.1.1.39) activities. Hence, P. aphrodite is an obligate crassulacean acid metabolism plant. Nevertheless, different night temperature greatly affected both the stomatal conductance and the contribution of ambient and respiratory CO(2) to the nocturnal accumulation of malate. However, the amounts of nocturnal accumulated malate and daily deposited starch appeared to have no significant difference between the two groups. These results demonstrate that P. ahrodite is congruent with the characteristics of CAM plants having great flexibility and plasticity in response to changes in environmental conditions. In addition, the formation of reproductive stem, viz. spike, was noticeably inhibited by a constant warm temperature, but induced by a fluctuating warm day and cool night condition. The relationship between the metabolic pool variation and spike induction of Phalaenopsis is also discussed.
Chen
Wen-Huei
WH
Department of Life Sciences, National University of Kaohsiung, No. 700 Kaohsiung University Rd, Nan-Tzu District 811, Kaohsiung, Taiwan, R O C.
Tseng
Ya-Chen
YC
Liu
Yo-Ching
YC
Chuo
Chuo-Min
CM
Chen
Pai-Ting
PT
Tseng
Kai-Meng
KM
Yeh
Yi-Chun
YC
Ger
Mang-Jye
MJ
Wang
Heng-Long
HL
D050260:Carbohydrate Metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002940:Circadian Rhythm; D003080:Cold Temperature; D003624:Darkness; D005453:Fluorescence; D005740:Gases / Q000378:metabolism; D008291:Malate Dehydrogenase / Q000378:metabolism; D029595:Orchidaceae / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D009930:Organic Chemicals / Q000378:metabolism*; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism; D054046:Plant Stomata / Q000502:physiology
D005740:Gases; D009930:Organic Chemicals; D002734:Chlorophyll; D002245:Carbon Dioxide; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+); D010730:Phosphoenolpyruvate Carboxylase