Past Attendees Biography

Chikodinaka Nkechinyere Okereke

Estonian University of Life Sciences, Estonia


Volatile Organic Compounds (VOCs) induced by abiotic stress in Carica papaya L

Chikodinaka Nkechinyere Okereke1, Eve kaurilind1, Arooran Kanagendran2, Leila Pazouki3, Ülo Niinemets1,4.

1 Estonian University of Life Sciences, Estonia

2 University of Neuchâtel, Switzerland

3 University of Louisville, Estonia

4 Estonian Academy of Sciences, Estonia

Plant species have to deal with quite a number of biotic and abiotic stresses throughout their life span. Plants frequently experience heat ramps of varying degrees, but how and to what extent plant metabolic activity and physiological make up recovers from mild and severe heat stress is poorly understood. Furthermore, information related to time-dependent changes in Volatile organic compound emission release in Carica papaya from heat stress is very limited. In this study, we exposed the leaves of Papaya to mild (37 and 41 °C), moderate (46 °C) and severe (49 °C) heat stress of 5 min through a 48h recovery period upon return to pre-stress conditions and studied the effects of various severities of heat shock treatments on leaf photosynthetic activity and VOC emissions so as to gain significant insight into temperature stress-induced volatile emissions. The mild heat treatment weakly affected foliage photosynthesis with an observable slight recovery while the severe stress inhibited photosynthesis with limited recovery observed. The heat stress treatment enhanced emissions of fatty acid derived compounds (FAD) and mono- and sesquiterpene, benzenoids, GDP pathway volatiles, GGDP pathway volatiles, Glucosinolate breakdown products and light weight oxygenated volatile compounds. At the induction of the heat stress, enhanced isoprene, mono- and sesquiterpene emissions were observed immediately after the heat treatment and gradually decreased through the recovery period. In contrast, fatty acid derived compounds (FAD), benzenoids, GDP pathway volatiles, GGDP pathway volatiles, Glucosinolate breakdown products and light weight oxygenated compounds remained high with observable fluctuations through the recovery period. Generally, this study shows the relationship between stress strength with regards to VOCs emission and responses.

Audience Take Away:

  • This study will expose the audience to the fact that when plants are stressed, they release volatiles (metabolites) which they use to protect themselves against these stresses.
  • These stresses could be biotic (herbivorous arthropods, plant pathogens, drought etc. or abiotic induced heat stress, ozone, wounding).
  • Plants response to stress and VOC emission has a significant effect on its physiological status.

This research demonstrates the effects of abiotic stress (induced heat stress) and how the severity of the stress from mild to severe elicitates the emission of VOCs; effects the foliage photosynthetic characteristics of plants and also gives an insight of what plant go through their lifecycles. The stresses can also be man-made and a knowledge about this will reduce the tress being inflicted on the plants by man; Knowing that these VOCs indirectly affects earth climate as they are precursors of secondary organic aerosols, photochemical ozone formation and high concentrations of VOC emissions could contribute to processes associated with global warming. This information I believe would be of help to curb multiple stress factors the affect plants in our environment and also encourage a platform to develop quantitative plant stress response models.


Chikodinaka Nkechinyere Okereke is a 3rd year PhD student at the Institute of Agricultural and Environmental Sciences at the Estonian University of Life Sciences. Tartu, Estonia. She got her in Agricultural engineering at Szent Istvan University Godollo, Hungary where she worked on the yield and biomass response of maize (Zea mays) to the application of foliar fertilizers. She is currently working on a variety of Stress-Induced Plant Volatiles in tropical plants under the supervision Professor Ülo Niinemets. She has worked on a variety of tropical plants such as Carica papaya, Amaranthus hybridus. She is interested in the impact of organic compounds on biosphere-atmosphere system.

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