title: Cool-night temperature induces spike emergence and affects photosynthetic efficiency and metabolizable carbohydrate and organic acid pools in Phalaenopsis aphrodite.
abstract: 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.
authors.affiliation: Department of Life Sciences, National University of Kaohsiung, No. 700 Kaohsiung University Rd, Nan-Tzu District 811, Kaohsiung, Taiwan, R O C.
authors.forename: Wen-Huei
authors.initials: WH
authors.lastname: Chen
authors.forename: Ya-Chen
authors.initials: YC
authors.lastname: Tseng
authors.forename: Yo-Ching
authors.initials: YC
authors.lastname: Liu
authors.forename: Chuo-Min
authors.initials: CM
authors.lastname: Chuo
authors.forename: Pai-Ting
authors.initials: PT
authors.lastname: Chen
authors.forename: Kai-Meng
authors.initials: KM
authors.lastname: Tseng
authors.forename: Yi-Chun
authors.initials: YC
authors.lastname: Yeh
authors.forename: Mang-Jye
authors.initials: MJ
authors.lastname: Ger
authors.forename: Heng-Long
authors.initials: HL
authors.lastname: Wang
mesh_terms: 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
chemical_list: D005740:Gases; D009930:Organic Chemicals; D002734:Chlorophyll; D002245:Carbon Dioxide; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+); D010730:Phosphoenolpyruvate Carboxylase