[PDF] Response of mitochondria to light intensity in the leaves of sun and





Previous PDF Next PDF



Toxicities of raw Alocasia odora

ornamental plant it may be frequently involved in accidental or intentional poisoning. Alocasia odora (A odora)

Alocasia lihengiae a new species of Araceae from Southern Yunnan

17 mars 2020 During our expeditions to Jinuo Mountains Xishuangbanna



Photosystem I in low light-grown leaves of Alocasia odora a shade

4 avr. 2021 a shade?tolerant plant is resistant to fluctuating light?induced ... Alocasia odora (G. Lodd) Spach plants were vegetatively.



Response of mitochondria to light intensity in the leaves of sun and

Alocasia odora and spinach plants were cultivated under both high and low light intensities Plant mitochondria have two ubiquinol-oxidizing pathways



Les plantes dappartement toxiques pour nos animaux de compagnie

Alocasia. - Aloès. - Amaryllis. - Anthurium et Arum des fleuristes La toxicité des plantes est variable selon la variété de la plante sa maturité



In vitro propagation of five Alocasia species

Plants of this genus are rhizomatous or bulbous perennials with large heart-shaped leaves. Alocasia species due to their foliar charm



Photosystem I in low light-grown leaves of Alocasia odora a shade

4 avr. 2021 a shade?tolerant plant is resistant to fluctuating light?induced ... Alocasia odora (G. Lodd) Spach plants were vegetatively.



Phytochemical Screening And Antimicrobial Study Of The Different

sanderiana Bull. An Endemic Philippine Plant the whole plant depending on the specie but for Alocasia ... On the other hand

Plant, Cell and Environment

(2005) 28
, 760-771 760

© 2005 Blackwell Publishing Ltd

Blackwell Science, LtdOxford, UKPCEPlant, Cell and Environment0016-8025Blackwell Science Ltd 2005? 2005

28?760771

Original Article

Respiration in sun and shade species

K. Noguchi

et al.

Correspondence: Ko Noguchi. Fax:

81 6 6850 5808; e-mail:

address: knoguchi@bio.sci.osaka-u.ac.jp Response of mitochondria to light intensity in the leaves of sun and shade species

KO NOGUCHI

1,2,3 , NICOLAS L. TAYLOR 2 , A. HARVEY MILLAR 2 , HANS LAMBERS 3 & DAVID A. DAY 2 1

Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyama-Cho, Toyonaka, Osaka, 560-

0043, Japan,

2 Biochemistry and Molecular Biology, School of Biomedical and Chemical Sciences and 3

School of Plant Biology,

the University of Western Australia, Australia

ABSTRACT

The present authors have shown previously that both res- piration rates and in vivo activities of the alternative oxi- dase (AOX) of leaves of

Alocasia odora

, a shade species, are lower than those in sun species, thereby optimizing energy production under limited light conditions (Noguchi et al

Australian Journal of Plant Physiology

28, 27-35,

2001). In the present study, mitochondria isolated from

A. odora leaves were examined in order to investigate the biochemical basis for the differences in respiratory param- eters.

Alocasia odora

and spinach plants were cultivated under both high and low light intensities, mitochondria were isolated from their leaves, and their respiratory prop- erties compared. Mitochondrial content of leaf extracts from the two species was estimated using fumarase activi- ties and antibody detection of porin (the voltage-dependent anion channel of the outer mitochondrial membrane). On a mitochondrial protein basis, spinach leaves showed higher capacities of the cytochrome pathway and cytochrome c oxidase (COX) than

A. odora

leaves. However, on a mito- chondrial protein basis,

A. odora

showed higher capacities of AOX, which had a high affinity for ubiquinone when activated by pyruvate.

Alocasia odora

also had larger amounts of mitochondrial protein per leaf dry weight, even under severely shaded conditions, than spinach. Lower growth light intensity led to lower activities of most path- ways and proteins tested in both species, especially glycine- dependent oxygen uptake. In the low light environment, most of the AOX protein in

A. odora

leaves was in its inactive, oxidized dimer form, but was converted to its reduced active form when plants were grown under high light. This shift may prevent over-reduction of the respira- tory chain under photo-oxidative conditions.

Key-words

Alocasia odora

Spinacia oleracea

; alternative oxidase (AOX); mitochondria; respiration; sun and shade.

INTRODUCTION

Plant mitochondria have two ubiquinol-oxidizing pathways,

the cytochrome pathway and the alternative pathway. Thelatter consists of one enzyme, the alternative oxidase

(AOX), and has the potential to catalyse apparently waste- ful respiration in higher plant mitochondria. Its role in plants has not been definitively identified, except for heat production in the spadix of Araceae species, but it is thought to prevent production of reactive oxygen species (ROS) in the respiratory chain, especially under environ- mental stress (Vanlerberghe & McIntosh 1997; Moore et al

2002; Vanlerberghe & Ordog 2002; Millenaar & Lambers

2003). However, many previous studies have imposed

severe physiological stresses on plants or cell cultures to induce changes in AOX activity or expression and conse- quently the ecophysiological role of AOX remains ambig- uous.

In vitro

regulation of AOX involves alteration of the redox state of the AOX protein, activation by a -keto acids (e.g. pyruvate), and the redox state of ubiquinone (Q) (Day & Wiskich 1995; Siedow & Umbach 2000). However, regu- lation of AOX activity in vivo remains unclear (Millenaar & Lambers 2003), because (1) AOX protein is more often than not in the reduced, activated form in crude extracts of plant tissues (e.g. Millenaar et al . 2001); (2) the total pyru- vate concentration in cells is high enough to fully activate

AOX, but the

in vivo pyruvate concentration in mitochon- dria is unknown (Siedow & Umbach 2000); and (3) the in vivo redox state of ubiquinone is rather stable (Millar et al

1998; Millenaar

et al . 2001). These studies have led to the notion that most of the AOX protein is fully activated in vivo . Further analyses are required to understand the in vivo regulation and the physiological significance of AOX. Shade species show slower rates of leaf photosynthesis and respiration than sun species, contributing to a positive carbon balance under very low light conditions, such as Noguchi, Sonoike & Terashima 1996; Noguchi & Terashima

1997).

In vivo

AOX activity in leaves of

Alocasia odora

, a shade species, is also low under light intensities similar to those in their natural habitat (Noguchi et al . 2001). Thus, in

A. odora

leaves, the respiratory system appears to be geared towards efficient ATP production. In contrast, in leaves of spinach, a high-light adapted plant, in vivo AOX activity was high at the beginning of the night and then decreased during the night, when plants were grown under a high light intensity (Azcón-Bieto, Lambers & Day 1983;

Noguchi

et al . 2001). Here we investigate the question of whether the leaves of

A. odora

have a smaller amount of

Respiration in sun and shade species

761

© 2005 Blackwell Publishing Ltd,

Plant, Cell and Environment,

28,

760-771

AOX or whether AOX is inactivated under low-light

conditions. Shade leaves within crops and other sun species, such as spinach, also show slower respiratory rates than leaves exposed to the sun (Noguchi et al . 1996).

In vivo

AOX activity in leaves of spinach is also low under these condi- tions (Noguchi et al . 2001), ensuring high efficiency of res- piration, which may be advantageous in shaded environments in which photosynthetic production is low. Slower rates of photorespiration in shade leaves would also enhance net production of photosynthate (Muraoka et al

2000). The photorespiratory pathway involves chloroplasts,

peroxisomes and mitochondria. In the mitochondria, gly- cine decarboxylase (GDC) converts glycine to serine, and produces NADH and NH 4 . We have also investigated the effect of light intensity on GDC and mitochondrial glycine oxidation.

MATERIALS AND METHODS

Plant materials and growth conditions

We used

Spinacia oleracea

L., a sun species, and

Alocasia

odora (Lodd.) Spach., a shade species. Seeds of

S. oleracea

were purchased from a local supermarket in Perth, Austra- lia. The seeds were germinated in soil and 10 d later the seedlings were transferred to 20-L containers with hydro- ponic nutrient solutions. Plants of

A. odora

were propa- gated vegetatively from rhizome segments. The mother plant was purchased at a local nursery in Perth. Seedlings from the rhizome segments were transferred to 20-L con- tainers with hydroponic nutrient solutions. Twelve seedlings were grown in each container. For 1 week after transfer, the plants received one-eighth of the following solutions: 4 m M KNO 3 , 4 m M Ca(NO 3 2 , 1.5 m M MgSO 4 , 1.33 m M KH 2 PO 4

0.05 m

M ethylenediaminetetraacetic acid (EDTA)-Fe,

0.01 m

M MnSO 4 , 1 m M ZnSO 4 , 1 m M CuSO 4 , 0.05 m M H 3 BO 3 , 0.5 m M Na 2 MoO 4 , 0.1 m M

NaCl, 0.2

m M CoSO 4 Thereafter, the plants received the full nutrient solution. The pH of the nutrient solutions was adjusted to 6.0 using NaOH. The nutrient solutions were replaced once a week. The containers were placed in a walk-in growth chamber. In the growth chamber, day/night temperature and humid- ity were 25/20

C and 60%, respectively, and the photope-

riod was 10 h. Black shade cloth was used to lower irradiance levels. The photosynthetic photon flux densities (PPFD) were 490, 200 and 20 m mol photons m 2 s 1 for high-light (HL), low-light (LL), and very low-light (VLL) conditions, respectively. As spinach did not grow under the VLL condition, we cultivated spinach under HL and LLquotesdbs_dbs48.pdfusesText_48