Effect Of Temperature And Oxygen Content On The Physiological And Gene Expression Of Energy-related Genes Of Harvested Kiwifruit

Energy is fundamental in all life activities. Recent investigations have shown thatthe development of senescence or deterioration of harvested horticultural crops maybe attributed to limited availability of energy or low energy production. However, theeffect of energy on horticultural crops is a relative complex process. At present, it isnot clear enough on the energy metabolism related physiological, biochemical andmolecular mechanism, especially in the way of energy metabolism regulation.Studying these issues in depth may provide new strategy in reducing the respiratorysubstrate consumption and improve organizational energy level, thereby extending thestorage life of horticultural crops. The effect of different temperature and differentoxygen content on respiration rate, ethylene production rate, energy status and thetranscript abundance of SnRK, AtpB, AAC, AOX and PUMP in harvested kiwifruitwere investigated. The major results were as follows:1. Three AAC genes, named AdAAC1, AdAAC2, AdAAC3, AtpB, AOX, PUMP andSnRK gene, named AdAtpB, AdAOX, AdPUMP and AdSnRK respectively, werecloned by RACE technology.2. Compared to room temperature storage, low temperature storage maintained ahigher level of firmness and a lower level of TSS, decreased respiration rate and theethylene production rate, reduced ATP, ADP, AMP and total adenylate level, energycharge, ATP/ADP ratio, enhanced the transcript abundance of AdAAC1, AdAAC2,AdAtpB, AdAOX, AdPUMP and AdSnRK, and decreased the transcript abundance ofAdAAC3.3. Compared to control, long-term N2treatment maintained a high level of firmnessand a lower level of TSS, decreased respiration rate and ethylene production rate,reduced ATP, ADP, AMP and total adenylate level; long-term O2treatment acceleratedthe aging of kiwifruit, promoted respiration rate and the ethylene production rate,enhanced ADP, AMP and total adenylate level, reduced energy charge and ATP/ADPratio.4. The transcript abundance of AdAAC1, AdAAC2, AdAtpB and AdSnRK fluctuated during the ripening and senescence process of harvested kiwifruit, transcriptabundance peak and lowest level of the four genes emerged almost at the same time.The trend of AdAOX transcript abundance was similar with that of AdPUMP, therewas no significant difference among the different treatments during the storage exceptthat they were significantly higher in the long-term O2treated fruit in the first day ofstorage.4. ATP, ADP and AMP level fluctuated during the ripening and senescence process ofharvested kiwifruit, and the order of the peaks time was AMP, ADP and ATP,respectively.It was concluded that the energy level of harvested kiwifruit was closely relatedto respiration activity. The ripening and senescence was regulated by energy levels.AdAAC1, AdAAC2, AdAtpB, AdAOX, AdPUMP and AdSnRK genes played importantroles in the balance of energy status.