Alternative and cytochrome pathway respiration during shoot bud formation in cultured Pinus radiata cotyledons

Abstract

1994. Atternative and cytochrome pathway respiration during shoot hod formation in cultwed Pinus radiata cotyledons. -Physiol. Plant, 90: 144-151.Respiration rates for exci.sed cotyledons of Pinus radiata cultured in the presence (shoot-fo'rming) and absence (non-shoot-forming) of N''-ben7.yladenine (BA) over a 21-day period were measured using a Clark-type oxygen electrode. The capacities and activities of cytochrome and altemative pathways of respiration were determined from titrations with KCN (1-10 mM) and .salicyihydroxamic acid (2-20 mM) individually and in combination. Respiration accounted for by alternative (AP) and cytochrome (CP) pathways varied with both culture treatment and age in culture. Rates of total respiration, CP respiration and AP activity rose concuri'ent with key developmental events of shoot bud formation. The greatest AP capacity was measured at day 3 in shoot-forming tissue. In contrast, for cotyledons cultured under non-shoot-forming conditions, no AP activity was observed after day 3 despite relatively constant AP capacity throughout the culture period. Although initial increases in cotyledon respiration during the culture period may be related to wounding and introduction to a tissue culture environment, later differences in re.spiratory patterns between shoot-forming and non-shoot-forming cotyledons appear to he associated with the cytokinin-induced developmental changes which give rise to .shoot primordia in cultured radiata pine cotyledons.

Analysis of Respiratory Chain Regulation in Roots of Soybean Seedlings1

“…The ontogenetic decline in total respiration and COX activity of our soybean roots correlated with a decline in root relative growth rate during aging, as reported by others (Azcö n- Bieto et al, 1983;McDonnell and Farrar 1993;Winkler et al, 1994;Lambers et al, 1996). The decline in Cyt pathway activity with age may reflect a decline in the demand for ATP associated with the slower growth rates, as has been suggested previously (Amthor, 1989).…”

“…Plant respiration can also increase rapidly in response to both biotic and abiotic stress (for a recent review, see Lambers et al, 1996). Conversely, decreases in respiratory rate often occur as plant tissues age (Azcon-Bieto et al, 1983; McDonnell and Farrar, 1993; Atkin and Cummins, 1994;Winkler et al, 1994). Various factors may be responsible for these changes, including substrate availability, enzyme activation, specific protein degradation or de novo protein synthesis, and alterations in mitochondrial numbers.…”

Leaf age‐related changes in respiratory pathways are dependent on complex I activity in Nicotiana sylvestris

“…It has been shown for a long time that respiration decreases with leaf age (reviewed in James 1953). More recently, a decrease in respiratory rate during tissue maturation has been demonstrated in bean leaves (Azcon‐Bieto et al 1983), barley roots (Mc Donnell and Farrar 1993) and Pinus radiata shoot buds (Winkler et al 1994). In addition to the main electron transport chain (ETC) consisting of complexes I–IV, mitochondria in plants and some fungi possess non‐proton‐pumping respiratory enzymes: various nicotinamide adenine dinucleotide phosphate (reduced) (NAD(P)H) alternative dehydrogenases by‐passing complex I (Møller 2001, Rasmusson et al 1999, 2004) and a cyanide‐resistant terminal oxidase [alternative oxidase (AOX)] branching at the level of the ubiquinone pool (Lambers 1982, reviewed in Vanlerberghe and McIntosh 1997).…”