Abstract
Thermoinhibition of Lactuca sativa L.cv. Great Lakes 659 seeds occurred at 36 ˚C. Thermoinhibition was alleviated by a combination of 100% O₂ and kinetin (10 mg dm⁻³). Chloramphenicol nullified the effect of O₂ plus kinetin. A number of mitochondrial activities (respiration, coupling, certain matrix enzyme activities and incorporation of [³⁵S]- methionine in mitochondrial proteins) were lower in thermoinhibited than in seeds imbibed at 25 ˚C. Treating seeds with plus kinetin at 36 °C restored these mitochondrial activities to the same or in some cases, to higher levels than in 25 °C control seeds.
Highlights
Evidence that thermoinhibition and the alleviation thereof by oxygen plus kinetin in Great Lakes lettuce seed is related to mitochondrialfunction
A num ber o f m itochondrial activities were low er in therm oinhibited than in seeds im bibed a t 25 “C. Treating seeds with plus kinetin at 36 °C restored these m itochondrial activities to the same o r in som e cases, to higher levels than in 25 °C control seeds
The results o f this study support the hypothesis that induction o f therm oinhibition is related to reduction in m itochondrial fu n ction and that stim ulation o f m itochondrial activity/developm ent could be causative in the alleviation o f thermoinhibition
Summary
M ateriaal Saad (strenggesproke dopvruggies) van L a c tu c a sa tiv a L. cv Great Lakes 659 is vanaf die Sensako saadmaatskappy verkry en in lugdigte glasbottels in die donker by 2"C geberg. Die resultate w at met hierdie behandeling verkry is, was dieselfde as w aar 100% 0^ kontinu vir die duurte van die eksperim ent deur die bottel geborrel is. ’n 100%O j-atm osfeer is verkry deur bottels aan die begin van ’n eksperim ent vir 30 min. Hierdie remm ing deur chlooram fenikol was egter nie ’n direkte remming van respirasie nie aangesien by voeging van chlooramfenikol tydens respirasiemeting van voorafwatergemkubeerde saad nie respirasie gerem het nie (resultate nie getoon). M itochondrionaktiwiteit Die resultate in tabel 5 toon dat hoëtemperatuur-inkubering van saad die respiratoriese kapasiteit van geisoleerde mitochondrions merkbaar met al drie substrate verlaag het. Suurstof plus kinetienbehandeling van saad het hierdie invloed opgehef en tot gevolg gehad dat die respiratoriese kapasiteit van mitochondrions soortgelyk was aan die van saad wat by 25 “C (water) geim bibeer is. 25 “ C-lug + HjO 25 “C-lug + CA 36 “ C-lug + HjO 36 “ C -O j + Kin 36 “ C-O^ + Kin + CA
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